Expansion of the basic knowledge on the inheritance of characters that allow the development of new maize breeding techniques / Expansión de los conocimientos básicos de la herencia de caracteres que posibiliten desarrollar nuevas técnicas de mejoramiento en maíz

ABSTRACT In order to increase the efficiency of maize hybrid seed production it is necessary to achieve a high grain yield to reduce production costs. This goal requires an expansion of the basic knowledge of the inheritance of characters in order to develop new breeding techniques to improve experimental materials with hard endosperm (flint). The balanced lethal system allows to study the relative contribution of different chromosome segments to hybrid vigour due to the heterozygosity of certain chromosome segments while the rest of the genome becomes homocygotic through continuous selfing. In this way, these segments can be transferred to inbred lines in order to increase grain yield or tassel size (to increase pollen production). The goal of this study was to transfer a heterotic segment by using a balanced lethal system regulated line (BLS14), through crosses and backcrosses, to S5 flint lines derived from two commercial hybrids, ACA 2000 and Cóndor with closed pedigree, with the objective of increase grain yield or tassel size for pollen production. The analysis of variance (ANOVA) and principal components analysis (PCA) showed a significant improvement in grain yield and tassel size in the S5 flint lines of both commercial hybrids, carrying the heterotic segment of the BLS14 line.

RESUMEN Para incrementar la eficiencia en la producción de semillas híbridas en maíz se necesitan altos rendimientos con un correlativo bajo costo de producción. Esto requiere una expansión de los conocimientos básicos de la herencia de caracteres que posibiliten desarrollar nuevas técnicas de mejoramiento sobre materiales experimentales de textura dura (flint). Los sistemas de letales balanceados permiten estudiar la contribución relativa de distintos segmentos heteróticos en el vigor híbrido dado que permiten lograr la heterocigosis cuasipermanente de una porción del genomio, mientras el resto del genoma se vuelve homocigota por autofecundaciones sucesivas. Estos sistemas pueden ser transferidos a líneas endocriadas para incrementar el rendimiento del grano y el tamaño de la panoja para aumentar la producción de polen. El objetivo de este trabajo fue incorporar un segmento heterótico de una línea regulada por un sistema de letales balanceados (BLS14), mediante cruzamiento y retrocruza, a líneas S5 derivadas de dos híbridos comerciales, ACA 2000 y Cóndor, de pedigree cerrado, con textura dura (flint), con la finalidad de aumentar el rendimiento en grano o el tamaño de la panoja para la producción de polen. Los análisis de variancia (ANOVA) y de componentes principales (ACP) mostraron un incremento significativo en el rendimiento del grano y el tamaño de la panoja de las líneas S5 de ambos híbridos comerciales, portando cada una de ellas el segmento heterótico proveniente de la línea BLS14.

Causes and consequences of DNA content variation in Zea / Causas y consecuencias de la variación del contenido de ADN en Zea

ABSTRACT Cytogenetic evidence indicates that Zea, which comprises maize (Z. mays ssp. mays) and its wild relatives, is an allopolyploid genus. Our research group has carried out numerous cytogenetic studies on Zea species, mainly focused on native Argentinian and Bolivian maize landraces. We found a wide inter- and intraspecific genome size variation in the genus, with mean 2C-values ranging between 4.20 and 11.36 pg. For the maize landraces studied here, it varied between 4.20 and 6.75 pg. The objectives of this work are to analyze the causes of genome size variation and to discuss their adaptive value in Zea. This variation is mainly attributed to differences in the heterochromatin located in the knobs and to the amount of interspersed DNA from retrotransposons. Polymorphisms in presence or absence of B-chromosomes (Bs) and the population frequency of Bs are also a source of genome size variation, with doses ranging between one and eight in the landraces analyzed here. Correlation analysis revealed that the percentage of heterochromatin is positively correlated with genome size. In addition, populations cultivated at higher altitudes, which are known to be precocious, have smaller genome sizes than do those growing at lower altitudes. This information, together with the positive correlation observed between the length of the vegetative cycle and the percentage of heterochromatin, led us to propose that it has an adaptive role. On the other hand, the negative relationship found between Bs and heterochromatic knobs allowed us to propose the existence of an intragenomic conflict between these elements. We hypothesize that an optimal nucleotype may have resulted from such intranuclear conflict, where genome adjustments led to a suitable length of the vegetative cycle for maize landraces growing across altitudinal clines.

RESUMEN La evidencia citogenética indica que el género Zea, el maíz (Z. mays ssp. mays) y sus parientes silvestres, posee un origen alopoliploide. Nuestro grupo de investigación ha realizado numerosos estudios en especies de Zea, principalmente en maíces nativos de Argentina y Bolivia. En este género, hallamos una amplia variación inter e intraespecífica en el tamaño del genoma, con valores 2C medios que oscilan entre 4,20 y 11,36 pg. El valor 2C medio de los maíces nativos estudiados varió entre 4,20 y 6,75 pg. Los objetivos de este trabajo son analizar las causas de la variación del tamaño del genoma en Zea y discutir su valor adaptativo. Esta variación se atribuye principalmente a las diferencias en la heterocromatina de los knobs y en la cantidad de ADN intercalado de los retrotransposones. Otras fuentes de variación son los polimorfismos para presencia/ausencia de cromosomas B (Bs) y para la frecuencia poblacional de Bs en las razas analizadas, con dosis que oscilan entre uno y ocho Bs. El porcentaje de heterocromatina se correlaciona positivamente con el tamaño del genoma. Las poblaciones cultivadas en altitudes altas, que son precoces, tienen tamaños de genoma más pequeños que las que crecen en bajas altitudes. Esta información, junto con la correlación positiva observada entre la duración del ciclo vegetativo y el porcentaje de heterocromatina, nos llevó a proponer el rol adaptativo de la heterocromatina. Por otro lado, la relación negativa encontrada entre Bs y knobs heterocromáticos nos permitió proponer la existencia de un conflicto intragenómico entre estos elementos. Hipotetizamos que de este conflicto intranuclear habría resultado el nucleotipo óptimo, donde ajustes genómicos condujeron a una duración adecuada del ciclo vegetativo en las razas de maíz que crecen a lo largo de clines altitudinales.

Caracterización y tipos de familias productoras de maíz local en la Frailesca, Chiapas / Typological characterization of the maize producing families from la Frailesca, Chiapas

Resumen Las Unidades de Producción Familiar (UPF) están conformadas por capitales natural, físico, financiero, humano y social. Los dos últimos constituyen la base del funcionamiento del resto y de la unidad de producción. En México, Chiapas y la Frailesca, la producción de maíces, particularmente de maíces locales, tiene valor cultural, agronómico y económico. El objetivo de esta investigación fue caracterizar las Unidades de Producción Familiar que cultivan maíces locales en la región Frailesca del estado de Chiapas, sobre la base cultural del manejo de los capitales humano y social. Se estudiaron 80 UPF de 20 comunidades seleccionadas mediante un muestreo por redes. Se utilizó el enfoque Modos de Vida Sustentable como marco de referencia. Se aplicaron entrevistas semiestructuradas y se realizaron observaciones participantes. En el estudio predominaron las familias nucleares con líderes de edad avanzada. Los jóvenes no priorizan la conservación de los maíces locales sino actividades más rentables como la ganadería, los maíces híbridos y el café. Existe un excesivo uso de agroquímicos que afecta los recursos suelo, agua y biodiversidad. Se distinguieron 6 tipos de UPF de acuerdo con sus capitales humano y social. El grupo 3 (G3) mostró un mejor equilibrio entre ambos por la participación familiar, destacándose entre los de mayor experiencia en el cultivo de maíces locales y por tener relaciones locales y de cooperación más sólidas. Se concluye que las UPF presentan características que contribuyen o afectan la conservación de los maíces locales, como la continuidad generacional, el deterioro de los recursos naturales que sostienen el cultivo a través de la fusión de las prácticas tradicionales con las modernas y la dependencia de recursos externos.

Abstract The Family Production Units (FPU) are made up of natural, physical, financial, human and social capital. The last two constitute the basis for the functioning of the rest of the capitals and of the production unit. In Mexico, Chiapas and La Frailesca, the production of corn, and particularly local corn, has cultural, agronomic, and economic value. The objective of this research was to characterize the UPF that cultivate local corn, in the Frailesca region of the State of Chiapas, on the cultural basis of the management of human and social capital. 80 UPF from 20 communities were studied, selected through network sampling. The Sustainable Livelihoods approach was used as a frame of reference. Semi-structured interviews were applied, and participant observations were made. In the predominant study in nuclear families with elderly leaders predominated. Young people do not prioritize the conservation of local corn, but rather more profitable activities such as livestock, hybrid corn and coffee. There is an excessive use of agrochemicals that affects soil, water and biodiversity resources. Six types of UPF were distinguished according to their human and social capital. The third category (G3) shows a better balance between human and social capital due to their family involvement, standingout among those with more experience in growing local corn and having stronger local relationships. It is concluded that the UPF present characteristics that foster or impair the preservation of local corn such as generational continuity, the deterioration of the natural resources that sustain the cultivation through the fusion of traditional and modern practices and dependence on external resources.

Comparative Study of Iron, Manganese and Nickel Contamination Potential of Disc and Hammer Milling Equipment and their Toxic Effect on Rat Kidney

Aim: To investigate the effect of hammer and disc milling equipment on the levels of Iron (Fe), Manganese (Mn) and Nickel (Ni) contents in maize (Zea mays) flour and the consequent impact on the kidney of albino rats. Study Design: The rats were randomly divided into groups of five rats per group. Six of the groups were fed with maize flour milled with a hammer mill, while the other six groups were fed with maize flour milled with a disc mill, and the thirteenth group was fed with crushed flour in a mortar and pestle as a control. The rats were sacrificed by decapitation under anesthesia on the 14th and 28th days. Place and Duration of Study: Departments of Biochemistry and Histology laboratories of the University of Jos, Nigeria, between, January to June, 2021. Methodology: For six days, a portion of the maize grains was milled with a hammer mill, another with a disc mill, and a third fraction was crushed into flour with a wooden mortar. The inductive coupled plasma mass spectrophotometric method was used to determine the levels of Fe, Mn, and Ni in maize flour. To avoid lysing the blood, blood samples were carefully collected by allowing it to run down the test tube's wall. The blood was allowed to coagulate at room temperature before being centrifuged and the serum collected and frozen until it was time for biochemical analysis. The kidneys of the rats were excised, cleaned, and preserved in chloroform until histological examinations were required. Results: The results show that Fe (325.16 ± 30.00 mg/kg and 205.05 ± 30.20 mg/kg) and Ni (20.92 ± 5.92 mg/kg and 18.00 ± 2.70 mg/kg) levels were extremely high in both disc and hammer milling machines. The Fe and Mn values in disc milled maize flour were higher than those in hammer milled maize flour. Rats in all groups had significantly higher serum urea, creatinine, K+, Na+, and Cl- levels than the control group. The kidney tissues of all the rats in the control and hammer-milled flour groups were normal, except for group 1 of the disc mill, which showed mild damage, according to the histopathological analysis. Conclusion: The Day 1 group fed with disc-milled flour showed a dense cast, atrophy, and nuclei loss in their kidney tissue. According to the results of the study, hammer milled maize flour is less harmful than disc milled maize flour, as shown by kidney histopathology.

Determination of Vitamin Contents of Maize (Zea mays L) Produced and Stocked from Rural Conditions in Cote D’ivoire

Aims: Maize is prized for its richness in nutrient compounds. Despite its socio-economic importance, maize faces a quality problem that is sometimes very delicate. Indeed, maize during different production, post-harvest processing, storage and transport conditions is exposed to bio-aggressors that can alter the quality of this cereal. With this in mind, this study was conducted to determinate the vitamins contents of maize produced and stored in five maize-producing regions of Côte d’Ivoire. Study Design: A total of 1 500 samples of maize as grains, epis and spathes were collected at rate of 500 samples by region (Gbêkê, Poro, Hambol, Indénié-Djuablin and Gontougo) and sent to the laboratory for analysis of the vitamin contents. Place and Duration of Study: This study was carried out during March 2016 to January 2017. Then, the analyses of the collected sample took place at the Biotechnology, Agriculture and Valorisation of Biological Ressources Laboratory of the Félix Houphouët-Boigny’s University, Abidjan. Methodology: Vitamins determination was carried by High Performance Liquid Chromatography. A total of twelve vitamins were evaluated namely 9 water-soluble vitamins (thiamin, riboflavin, niacin, choline, pantothenic acid, pyridoxine, biotin, folic acid and cobalamin) and 3 fat-soluble vitamins (β-carotene, vitamin E and K). Results: Results show a significant difference between vitamins contents of the different maize forms and regions. The mean values ranged from 0.09 ± 0.04 to 557.24 ± 10.97 mg / kg for water-soluble vitamins and from 0.31±0.25 to 4.20±1.00 mg / kg for fat-soluble vitamins. Choline was the most abundant of the water-soluble vitamins while β-carotene and vitamin E were the most abundant of the fat-soluble vitamins. Maize grains and epis had the highest levels of these vitamins all of the regions. Maize spathes samples, especially those from Indénié-Djuablin and Gontougo, showed the lowest concentrations. Conclusion: A significant variability from one region to another can be noticed at level of vitamins regardless the type of maize. Maize vitamin contents seem to be related to maize form (grains, epis, spathes), maize variety, agronomic practices, post-harvest treatments and storage structure.

Effects of Mulching on Soil Water Content, Maize Performance and Weed Growth in Dry Land Area of Bangladesh

Aims: The objectives of the research work were to evaluate the effects of mulching on soil water content, maize performance and weed growth in dry land area of Bangladesh Study Design: The experiment was laid out in a randomized complete block design (RCBD) with three replications Place and Duration of Study: Central research field of Sher-e-Bangla Agricultural University, Dhaka-1207 during November 2019 to April 2020. Methodology: The experimental field is divided into 3 blocks to represent 3 replications. There are 6 unit plots (each unit plot consists of 3m � 2m area) in the experimental farm. Distances of 1 m and 0.5 m are maintained between replication to replication and plots to plots, respectively. Plant to plant and row to row distances are considered to be 0.25 m and 0.75 m, respectively. The treatments are assigned in random plots. The land is ploughed four times followed by laddering to have fine tilth of the soil. The maize cultivars Shuvra and KS-510 are used as plant materials. Fig. 1 represents the six mulch treatments are imposed on the plants: Control (without mulch, CK), water hyacinth dry (10 t/ha, WH), rice straw dry (10 t/ha, RS), black polythene (4m � 3m, BP), white polythene (4m � 3m, WP), and transparent polythene (4m � 3m, TP) (S2). The mulches are applied as per treatment in each plot just after sowing to maintaining an equal thickness throughout the plot. Dried and cleaned mulches are used before applying to the experiment. The significance of the difference among the treatment means were estimated by the MSTAT-C package programme at 5% level of probability. Results: It is found in the experimental results that the soil water content of the no-mulching treatment is lower as compared to that of the other treatments from 0-10 cm, 10-20 cm and 20-30 cm soil depths. It is also observed that the RS mulching provides the highest soil water content, leaf area index (LAI), chlorophyll contents, and total biomass. Significant enhancement of maize yield (20.55 ton/ha) is recorded for the rice straw mulching. In contrast, the weed dry weight of 7.45g/m2 is observed in the RS mulching, which is lower than the other treatments. Conclusions: Therefore, it can be concluded that the RS mulching, compared to other mulching, would be more efficient for maximum utilization of limited water resources, weed suppression as well as to increase the maize yield. The present research approach would be applicable to manage the soil water for enhancing the maize production in dry land area.

Genome-wide analysis of metallothionein gene family in maize to reveal its role in development and stress resistance to heavy metal

BACKGROUND: Maize (Zea mays L.) is a widely cultivated cereal and has been used as an optimum heavy metal phytoremediation crop. Metallothionein (MT) proteins are small, cysteine-rich, proteins that play important roles in plant growth and development, and the regulation of stress response to heavy metals. However, the MT genes for maize have not been fully analyzed so far. METHODS: The putative ZmMT genes were identified by HMMER. The heat map of ZmMT genes spatial expression analysis was generated by using R with the log2 (FPKM + 1). The expression profiles of ZmMT genes under three kinds of heavy metal stresses were quantified by using qRT-PCR. The metallothionein proteins was aligned using MAFFT and phylogenetic analysis were constructed by ClustalX 2.1. The protein theoretical molecular weight and pI, subcellular localization, TFs binding sites, were predicted using ProtParam, PSORT, PlantTFDB, respectively. RESULTS: A total of 9 ZmMT genes were identified in the whole genome of maize. The results showed that eight of the nine ZmMT proteins contained one highly conserved metallothio_2 domain, while ZmMT4 contained a Metallothio_PEC domain. All the ZmMT proteins could be classified into three major groups and located on five chromosomes. The ZmMT promoters contain a large number of hormone regulatory elements and hormone-related transcription factor binding sites. The ZmMT genes exhibited spatiotemporal specific expression patterns in 23 tissues of maize development stages and showed the different expression patterns in response to Cu, Cd, and Pb heavy metal stresses. CONCLUSIONS: We identified the 9 ZmMT genes, and explored their conserved motif, tissue expression patterns, evolutionary relationship. The expression profiles of ZmMT genes under three kinds of heavy metal stresses (Cu, Cd, Pb) were analyzed. In summary, the expression of ZmMTs have poteintial to be regulated by hormones. The specific expression of ZmMTs in different tissues of maize and the response to different heavy metal stresses are revealed that the role of MT in plant growth and development, and stress resistance to heavy metals.

A 6-year field monitoring of fall armyworm, Spodoptera frugiperda, in transgenic Bt maize in Brazil

ABSTRACT A 6-year field monitoring study was designed to compare the presence of fall armyworm Spodoptera frugiperda (J. E. Smith), leaf injury, its parasitoids, 100 seed weight, and seed yield of Bt maize hybrids approved for commercialization in the Brazilian market. Field trials were planted in two municipalities, divided into two periods, from 2011 to 2014 (period I), and due to the approval of different Bt hybrids, from 2015 to 2016 (period II). Treatments were Bt, non-Bt maize and all non-Bt maize sprayed with insecticide methomyl. Six Bt-maize hybrids were planted, expressing the following proteins: Cry1Ab, Cry1F, Cry1A.105 (Cry1Ab +Cry1Ac +Cry1F), Cry2Ab2a and Vip3. In 2015 and 2016 Bt Powercore was planted due to its commercial approval. The number of S. frugiperda larvae for most Bt hybrids was lower than on non-Bt hybrids, except for Fórmula TL and Herculex in period II, in both municipalities. In period I, Bt hybrids VT, VT 2 and Viptera showed almost no injury on their leaves, despite the high number of fall armyworm larvae found in plants. Different parasitoids emerged from larvae from Bt and non Bt hybrids: Archytas sp., Campoletis sp., Chelonus sp., Eiphosoma sp. and Ophion luteus. The average 100 seed weight was higher in municipality from Sete Lagoas for all Bt hybrids, non-Bt hybrids and non-Bt hybrids sprayed with methomyl, when compared to Nova Porteirinha during period I. Fórmula TL, non-Bt Fórmula TL sprayed with methomyl, and non-Bt Fórmula TL showed the lowest seed yield in both municipalities and periods.

Fungivory: a new and complex ecological function of Doru luteipes (Scudder) (Dermaptera: Forficulidae) / Fungivoria: uma nova e complexa função ecológica de Doru luteipes (Scudder) (Dermaptera: Forficulidae)

We report the discovery that the earwig predator Doru luteipes (Scudder, 1876) (Dermaptera: Forficulidae) feed on Puccinia polysora Underw uredospore, the causal agent of Southern Rust of Corn (SRC), which is a primary disease affecting the maize crop in Brazil. We performed experiments in laboratory and greenhouse to test the effect of D. luteipes (1st/2nd and 3rd/4th instars, and adults) fungivory on the P. polysora uredospore concentration. All trials showed a significant reduction of the initial concentration of uredospore. There was a reduction in uredospore concentration with increase in number of D. luteipes feeding on them. We also tested the uredospore consumption by quantifying its percentage in the feces of D. luteipes. Nymphs of the 2nd, 4th instar and adults fed 88%, 85%, and 83.8% of the uredospore, respectively. For nymphs of the 3rd instar, the percentage of uredospore consumption (75.6%) was statistically significant compared with the other groups. In greenhouse experiment, at twenty-eight days after plant inoculation with 9.9 x 104 uredospores, the percentage of uredospore consumption was 81.7%. Our results confirmed the fungivory of D. luteipes on P. polysora uredospore. This is the first report of D. luteipes fungivory, which may play an important role in the biological control of P. polysora in corn.

Relatamos a descoberta de que o predador Doru luteipes (Scudder, 1876) (Dermaptera: Forficulidae) se alimenta de uredosporos de Puccinia polysora Underw, o agente causal da ferrugem polisora que é uma doença primária que afeta a cultura do milho no Brasil. Realizamos experimentos em laboratório e em casa de vegetação para testar o efeito da fungivoria de D. luteipes (1º/2º e 3º/4º iìstares e adultos) sobre a concentração de uredosporos de P. polysora. Todos os ensaios mostraram uma redução significativa da concentração inicial de uredosporos. Houve uma redução na concentração de uredosporos com o aumento do número de D. luteipes alimentando-se deles. Também testamos o consumo de uredosporos quantificando sua porcentagem nas fezes de D. luteipes. Ninfas do 2º e 4º ínstar, assim como adultos, alimentaram-se de 88%, 85% e 83,8% dos uredosporos, respectivamente. Para ninfas do 3º ínstar, a porcentagem de consumo de uredosporos (75,6%) foi estatisticamente significativo em comparação com os outros grupos. No experimento em casa de vegetação, aos 28 dias após a inoculação das plantas com 9,9 x 104 uredosporos, a porcentagem de consumo de uredosporos foi de 81,7%. Nossos resultados confirmaram a fungivoria de D. luteipes em uredosporos de P. polysora. Este é o primeiro relato de fungivoria de D. luteipes, que pode ter papel importante no controle biológico de P. polysora em milho.

Fungivory: a new and complex ecological function of Doru luteipes (Scudder) (Dermaptera: Forficulidae) / Fungivoria: uma nova e complexa função ecológica de Doru luteipes (Scudder) (Dermaptera: Forficulidae)

We report the discovery that the earwig predator Doru luteipes (Scudder, 1876) (Dermaptera: Forficulidae) feed on Puccinia polysora Underw uredospore, the causal agent of Southern Rust of Corn (SRC), which is a primary disease affecting the maize crop in Brazil. We performed experiments in laboratory and greenhouse to test the effect of D. luteipes (1st/2nd and 3rd/4th instars, and adults) fungivory on the P. polysora uredospore concentration. All trials showed a significant reduction of the initial concentration of uredospore. There was a reduction in uredospore concentration with increase in number of D. luteipes feeding on them. We also tested the uredospore consumption by quantifying its percentage in the feces of D. luteipes. Nymphs of the 2nd, 4th instar and adults fed 88%, 85%, and 83.8% of the uredospore, respectively. For nymphs of the 3rd instar, the percentage of uredospore consumption (75.6%) was statistically significant compared with the other groups. In greenhouse experiment, at twenty-eight days after plant inoculation with 9.9 x 104 uredospores, the percentage of uredospore consumption was 81.7%. Our results confirmed the fungivory of D. luteipes on P. polysora uredospore. This is the first report of D. luteipes fungivory, which may play an important role in the biological control of P. polysora in corn.

Relatamos a descoberta de que o predador Doru luteipes (Scudder, 1876) (Dermaptera: Forficulidae) se alimenta de uredosporos de Puccinia polysora Underw, o agente causal da ferrugem polisora que é uma doença primária que afeta a cultura do milho no Brasil. Realizamos experimentos em laboratório e em casa de vegetação para testar o efeito da fungivoria de D. luteipes (1º/2º e 3º/4º iìstares e adultos) sobre a concentração de uredosporos de P. polysora. Todos os ensaios mostraram uma redução significativa da concentração inicial de uredosporos. Houve uma redução na concentração de uredosporos com o aumento do número de D. luteipes alimentando-se deles. Também testamos o consumo de uredosporos quantificando sua porcentagem nas fezes de D. luteipes. Ninfas do 2º e 4º ínstar, assim como adultos, alimentaram-se de 88%, 85% e 83,8% dos uredosporos, respectivamente. Para ninfas do 3º ínstar, a porcentagem de consumo de uredosporos (75,6%) foi estatisticamente significativo em comparação com os outros grupos. No experimento em casa de vegetação, aos 28 dias após a inoculação das plantas com 9,9 x 104 uredosporos, a porcentagem de consumo de uredosporos foi de 81,7%. Nossos resultados confirmaram a fungivoria de D. luteipes em uredosporos de P. polysora. Este é o primeiro relato de fungivoria de D. luteipes, que pode ter papel importante no controle biológico de P. polysora em milho.

Fungivory: a new and complex ecological function of Doru luteipes (Scudder) (Dermaptera: Forficulidae)

Abstract We report the discovery that the earwig predator Doru luteipes (Scudder, 1876) (Dermaptera: Forficulidae) feed on Puccinia polysora Underw uredospore, the causal agent of Southern Rust of Corn (SRC), which is a primary disease affecting the maize crop in Brazil. We performed experiments in laboratory and greenhouse to test the effect of D. luteipes (1st/2nd and 3rd/4th instars, and adults) fungivory on the P. polysora uredospore concentration. All trials showed a significant reduction of the initial concentration of uredospore. There was a reduction in uredospore concentration with increase in number of D. luteipes feeding on them. We also tested the uredospore consumption by quantifying its percentage in the feces of D. luteipes. Nymphs of the 2nd, 4th instar and adults fed 88%, 85%, and 83.8% of the uredospore, respectively. For nymphs of the 3rd instar, the percentage of uredospore consumption (75.6%) was statistically significant compared with the other groups. In greenhouse experiment, at twenty-eight days after plant inoculation with 9.9 x 104 uredospores, the percentage of uredospore consumption was 81.7%. Our results confirmed the fungivory of D. luteipes on P. polysora uredospore. This is the first report of D. luteipes fungivory, which may play an important role in the biological control of P. polysora in corn.

Resumo Relatamos a descoberta de que o predador Doru luteipes (Scudder, 1876) (Dermaptera: Forficulidae) se alimenta de uredosporos de Puccinia polysora Underw, o agente causal da ferrugem polisora que é uma doença primária que afeta a cultura do milho no Brasil. Realizamos experimentos em laboratório e em casa de vegetação para testar o efeito da fungivoria de D. luteipes (1º/2º e 3º/4º iìstares e adultos) sobre a concentração de uredosporos de P. polysora. Todos os ensaios mostraram uma redução significativa da concentração inicial de uredosporos. Houve uma redução na concentração de uredosporos com o aumento do número de D. luteipes alimentando-se deles. Também testamos o consumo de uredosporos quantificando sua porcentagem nas fezes de D. luteipes. Ninfas do 2º e 4º ínstar, assim como adultos, alimentaram-se de 88%, 85% e 83,8% dos uredosporos, respectivamente. Para ninfas do 3º ínstar, a porcentagem de consumo de uredosporos (75,6%) foi estatisticamente significativo em comparação com os outros grupos. No experimento em casa de vegetação, aos 28 dias após a inoculação das plantas com 9,9 x 104 uredosporos, a porcentagem de consumo de uredosporos foi de 81,7%. Nossos resultados confirmaram a fungivoria de D. luteipes em uredosporos de P. polysora. Este é o primeiro relato de fungivoria de D. luteipes, que pode ter papel importante no controle biológico de P. polysora em milho.

Ingeniería genética contra estrés abiótico en cultivos neotropicales: osmolitos, factores de transcripción y CRISPR/Cas9 / Genetic engineering against abiotic stress in Neotropical crop plants: osmolites, transcription factors and CRISPR/Cas9

RESUMEN El neotrópico es sitio de origen de gran variedad de plantas que actualmente son cultivadas con éxito en diferentes regiones del mundo. Sin embargo, condiciones climáticas adversas, que se pueden ver acrecentadas por efectos del cambio climático antropogénico, pueden afectar su rendimiento y productividad debido a las situaciones de estrés abiótico que se pueden generar. Como alternativa para contrarrestar estos efectos, se ha experimentado con modificaciones genéticas, particularmente en genes relacionados con la producción de osmolitos y factores de transcripción que han llevado a que estas plantas, a nivel experimental, tengan mayor tolerancia a estrés oxidativo, altas y bajas temperaturas y fotoinhibición, sequía y salinidad, mediante la acumulación de osmoprotectores, la regulación en la expresión de genes y cambios en el fenotipo. En este trabajo se presentan y describen las estrategias metodológicas planteadas con estos fines y se complementan con ejemplos de trabajos realizados en cultivos de origen neotropical de importancia económica, como maíz, algodón, papa y tomate. Además, y debido a la novedad y potencial que ofrece la edición génica por medio del sistema CRISPR/Cas9, también se mencionan trabajos realizados en plantas con origen neotropical, enfocados en comprender e implementar mecanismos de tolerancia a sequía. Las metodologías aquí descritas podrían constituirse en opciones prácticas para mejorar la seguridad alimentaria con miras a contrarrestar las consecuencias negativas del cambio climático antropogénico.

ABSTRACT The neotropics are the site of origin of a large variety of plants that are currently successfully cultivated in different regions of the world. However, adverse climatic conditions, which can be exacerbated by the effects of anthropogenic climate change, can affect their yield and productivity due to the abiotic stresses that can be generated. As an alternative to counteract these effects, genetic modifications have been experimentally implemented, particularly in genes related to osmolyte production and transcription factors, which have ultimately led to increased tolerance of these plants to oxidative stress, high and low temperatures and photoinhibition, drought and salinity, through the accumulation of osmoprotectants, regulation of gene expression and changes in phenotype. In this work, the methodological strategies proposed to these aims are presented and described, and they are complemented with examples of studies carried out in economically important crops of neotropical origin, such as corn, cotton, potato and tomato. In addition, and due to the novelty and potential that gene editing offers through the CRISPR/Cas9 system, works conducted in plants with neotropical origin, focused on understanding and implementing drought tolerance mechanisms, are also mentioned. The methodologies described here could become practical options to achieve food security in the frame of the adverse effects caused by anthropogenic climate change.

Modelos multivariados en la búsqueda de regiones genómicas para resistencia a mal de río cuarto y bacteriosis en maíz / Multi-trait models for genomic regions associated with mal de río cuarto and bacterial disease in maize

RESUMEN La producción de maíz (Zea Mays L.) ha sido ampliamente beneficiada con la mejora de líneas endocriadas respecto a la resistencia a enfermedades causadas por virus y hongos. Sin embargo, es notable la ausencia de genotipos resistentes a bacteriosis. El objetivo del presente estudio fue identificar regiones genómicas para la mejora de resistencia a Mal de Río Cuarto (MRC) y a bacteriosis (BD) en un germoplasma diverso de maíz. Se evaluó, para ambas enfermedades, una población diversa de líneas de maíz en el ciclo de cultivo 2019-2020 en la región argentina donde la virosis MRC es endémica. Se estimó incidencia y severidad de MRC y BD en cada línea y se realizó un estudio de mapeo por asociación (GWAS) con 78.376 marcadores SNPs. Un modelo multicarácter se utilizó para evaluar simultáneamente la resistencia a MRC y BD en las líneas evaluadas. El germoplasma evidenció alta variabilidad genética tanto para la mejora de la resistencia a MRC como a BD, pero no se observó correlación genética significativa entre la respuesta a ambas enfermedades. Se identificaron regiones genómicas promisorias para resistencia a MRC y a BD, que serán confirmadas en evaluaciones en nuevos ambientes.

ABSTRACT Maize (Zea Mays L.) production has been greatly benefited from the improvement of inbred lines in regard to the resistance to diseases. However, the absence of resistant genotypes to bacteriosis is remarkable. The aim of the study was to identify genomic regions for resistance to Mal de Río Cuarto (MRC) and to bacterial disease (BD) in a diverse maize germplasm evaluated in the Argentinian region where MRC virus is endemic. A maize diverse population was assessed for both diseases during the 2019-2020 crop season. Incidence and severity of MRC and BD were estimated for each line and a genome wide association study (GWAS) was conducted with 78,376 SNP markers. A multi-trait mixed linear model was used for simultaneous evaluation of resistance to MRC and BD in the scored lines. The germplasm showed high genetic variability for both MRC and BD resistance. No significant genetic correlation was observed between the response to both diseases. Promising genomic regions for resistance to MRC and BD were identified and will be confirmed in further trials.

Perfil nutricional y estrategias de publicidad en el empaque de alimentos procesados de trigo y maíz en la Ciudad de México / Nutrient profile and marketing strategies of processed wheat and maize products in Mexico City

Resumen: Objetivo: Evaluar la asociación entre el perfil nutricional y las estrategias de publicidad de alimentos procesados de trigo y maíz (APTM) ofertados en puntos de venta de la Ciudad de México. Material y métodos: Se recolectó información del contenido nutricional y tipos de publicidad para doce categorías de APTM en 58 puntos de venta localizados en zonas de niveles socioeconómicos (NSE) bajo y alto. Resultados: El 8.5 y 10.7% de APTM en NSE bajo y alto fueron saludables, respectivamente. ≤12% de los APTM fueron saludables, excepto harinas (~30%) y pastas (~95%). Entre ambos NSE, de 28.3% a 31.9% de APTM usaron personajes, de 46.5% a 50.1% promociones y de 38.2% a 41.3% claims. Se encontraron asociaciones significativas (p<0.001) en el uso de publicidad de APTM no saludables en ambas zonas de NSE. Conclusiones: La mayoría de los APTM en venta fueron no saludables, y se ofertaron más en el NSE bajo. En ambos NSE la mayoría de APTM no saludables usa estrategias publicitarias para estimular su consumo.

Abstract: Objective: To evaluate the nutrient profile and marketing techniques (MT) of processed wheat and maize foods (PWMF) sold in food retail outlets of Mexico City. Materials and methods: We collected information on nutrient content and MT for PWMF across twelve food categories from 58 retail outlets in high and low income areas of Mexico City. Results: Roughly 8.5% and 10.7% of PWMF, in low and high income areas were healthy, respectively. The ≤12% of PWMF were healthy, except for flours (~33%) and pastas (≥95%). Across both income areas, 28.3%-31.9% of WMPF employed characters, 46.5%-50.1% promotions and 38.2%-41.3% claims. A significant association (p<0.001) was found between the use of MT and unhealthy PWMF in both areas. Conclusion: The majority of PWMF available in the food retail sector were considered unhealthy, which were being more offered in low income areas. Across income areas, the majority of unhealthy WMPF employed MT to encourage consumption.

Nitrogen coated fertilizer with controlled release for the maize crop / Fertilizante revestido com nitrogênio com liberação controlada para a cultura do milho

Maize represents one of the most cultivated crops of cereals in the world, being used as a source of grain, silage and biofuel. Nitrogen is very required in the maize crop, making nitrogen fertilization a significant part of the production cost. The objective of this study was to evaluate the response of two sources of N, urea and coated urea of controlled release, regarding the productivity and the cost/benefit ratio in maize for 2nd harvest. The experiment was carried out in the field in soil classified as dystroferric Red Latosol and treatments distributed in experimental plots, following the randomized block design with four replications. The treatments were 40 kg N ha-1 of common urea; 60 kg N ha-1 of common urea; 40 kg N ha-1 of coated urea; 60 kg of N-coated urea and the control without application of N broadcast application in planting. The maize crop responded to the application of nitrogen at planting. However, the use of coated urea did not increase the grain yield in relation to the use of common urea. The economic analysis demonstrated a better efficiency of use of N and the best net revenues with the application of the dose of 40 kg N ha -1 of common urea in the planting of the crop.

O milho representa uma das culturas de cereais mais cultivadas no mundo, sendo utilizado como fonte de grãos, silagem e biocombustível. O nitrogênio é muito necessário na cultura do milho, tornando a fertilização nitrogenada uma parte significativa do custo de produção. Este trabalho teve como objetivo avaliar o fertilizante nitrogenado revestido de liberação controlada para a cultura do milho de 2ª safra. O trabalho foi desenvolvido na Fazenda Estância Maracaju, localizada no município de Maracaju ­ Mato Grosso do Sul. As parcelas experimentais foram constituídas por 48 linhas com espaçamento de 0,5 metros por 1000 metros de comprimento entre si. Como área útil considerou-se as 30 linhas centrais (1,5 ha). Os tratamentos utilizados foram T1: 40 kg ha-1 de N de ureia comum; T2: 60 kg ha-1 de N de ureia comum; T3: 40 kg ha-1 de N de ureia revestida; T4: 60 kg de N de ureia revestida e T5: sem aplicação de N. Os tratamentos foram distribuídos nas unidades experimentais segundo delineamento de blocos ao acaso com quatro repetições. A cultura de milho, respondeu aplicação de nitrogênio no plantio. O uso de ureia revestida não influenciou na produtividade de grãos em relação a ureia comum no milho de 2ª safra. A melhor eficiência de uso de N e a melhor receita líquida é com a dose de 40 kg de N ureia ha-1, de ureia comum aplicado no plantio da cultura.

Genetic characterization of maize doubled haploid lines for Fusarium stalk rot caused by Fusarium verticillioides

Fusarium stalk rot disease (FSR) of maize caused by Fusarium verticillioides (Sacc.) Nirenberg is becoming an important biotic production constraint in many of the major maize growing areas causing substantial yield losses. Inbreds are preferred as parents in hybrid development owing to homozygous nature and high heterotic ability. Double haploid (DH) technology has emerged as a significant milestone. A total of 339 DH lines were generated from two inbred lines, VL1043 (susceptible) and CM212 (resistant), through in vivo haploid induction method. The 339 DH lines along with parents were phenotyped for their response to the FSR at the College of Agriculture, V. C. Farm, Mandya, India during summer, kharif and rabi seasons of the 2019–2020. Best linear unbiased predictors (BLUPs) were estimated for the FSR disease scores over three seasons. A wide range of BLUP scores of three to nine indicated the presence of higher variation for response of DH lines to FSR disease. The higher estimates of standardized range (1.31) and phenotypic coefficient of variation (19.80) also displayed higher variability. Nine lines were moderately resistant and 188 exhibited moderately susceptible reaction. The distribution of DH lines was positively skewed (1.34) and platykurtic (2.31) which suggested complementary epistasis and involvement of large number of genes in the disease expression.

Beef quality of Nellore steers fed dried or rehydrated and ensiled corn or sorghum grains / Calidad de la carne de Ganado Nelore alimentado con grano de maíz o sorgo seco o rehidratado y ensilado / Qualidade de carne de bovinos Nelore alimentados com grãos de milho ou sorgo seco ou reidratado e ensilado

Abstract Background: Rehydration of grains, such as corn and sorghum, is used to increase nutrient absorption. However, the effect of this practice on meat quality is poorly understood. Objective: To evaluate the effects of type of grain and processing on the meat quality of Nellore steers in a feedlot. Methods: Twenty-four non-castrated Nellore steers (270 ± 53 kg initial body weight) were distributed in a completely randomized 2×2 factorial design, with six replicates. The first factor was cereal type (corn or sorghum), and the second was the grain processing (dry or rehydrated and ensiled). The diets were composed of 30% corn silage and 70% concentrate. Sixty days before the beginning of the experiment, corn and sorghum grains were rehydrated and ensiled. The animals were slaughtered after 140 days of confinement. Meat quality analyses were determined in samples of fresh and aged meat (7 days) from the Longissimus lumborum muscle. Results: no difference between treatments was observed for carcass pH and L* (lightness), a* (redness), and b* (yellowness) values, shear force, thawing and cooking losses, and chemical composition of meat (p>0.05). The b* (yellowness) value of subcutaneous fat was higher in steers fed corn, regardless of grain processing (p=0.03). Sarcomere length was higher in aged meat of steers fed sorghum, regardless of processing method (p=0.01). Conclusions: the grain processing method does not affect beef quality; however, grain type can affect subcutaneous fat color and sarcomere length of aged beef.

Resumen Antecedentes: La rehidratación de granos, tales como maíz y sorgo, se usa para aprovechar mejor sus nutrientes. Sin embargo, es poco conocido el efecto de esta práctica sobre la calidad de la carne. Objetivo: Evaluar los efectos del tipo de cereal y su procesamiento sobre la calidad de carne de toretes Nelore en confinamiento. Métodos: Veinticuatro novillos Nelore enteros con un peso promedio inicial de 270 ± 53 kg, se distribuyeron en un diseño factorial 2×2 completamente aleatorizado (n=6). El primer factor fue el tipo de cereal (maíz o sorgo) y el segundo fue su procesamiento (seco o rehidratado y ensilado). Las dietas estuvieron compuestas por 28,44% de ensilaje de maíz y 71,56% de concentrado. Sesenta días antes de iniciar el experimento, los granos de maíz y sorgo se rehidrataron y ensilaron. Los animales se sacrificaron después de 140 días de confinamiento. La calidad de la carne se determinó en muestras de carne fresca y madurada (7 días) obtenidas del músculo Longissimus lumborum. Resultados: No hubo diferencias entre tratamientos para el pH de las canales, ni para los valores de color (L* "luminosidad", a* "intensidad de rojo" y b* "intensidad de amarillo"), fuerza de corte, composición química, o pérdidas de agua por descongelamiento o cocción (p>0,05). El valor de b* de la grasa subcutánea fue mayor en los novillos alimentados con maíz, independientemente del tipo de procesamiento (p=0,03). La longitud de sarcómero fue más alto en la carne madurada de novillos alimentados con sorgo, sin importar el método de procesamiento (p=0,01). Conclusiones: El método de procesamiento del grano no afecta la calidad de la carne; sin embargo, el tipo de cereal afecta el color de la grasa subcutánea y la longitud del sarcómero de la carne madurada.

Resumo Antecedentes: A reidratação de grãos, como milho e sorgo, tem sido usada para aumentar a utilização de seus nutrientes. Contudo, o efeito dessa prática na qualidade da carne é pouco compreendido. Objetivo: Avaliar os efeitos do tipo de grão de cereais e seu processamento sobre a qualidade da carne de bovinos confinados. Métodos: Vinte e quatro bovinos Nelore não castrados, com peso corporal médio inicial de 270 ± 53 kg foram distribuídos em delineamento inteiramente casualizado, fatorial 2×2, com seis repetições. O primeiro fator foi o tipo de grão de cereal no concentrado (milho ou sorgo), e o segundo foi o processamento destes grãos (seco ou reidratado e ensilado). As dietas foram compostas por 28,44% de silagem de milho e 71,56% de concentrado. Sessenta dias antes do início do experimento, os grãos de milho e sorgo foram reidratados e ensilados. Os animais foram abatidos após 140 dias de confinamento. As análises de qualidade da carne foram determinadas em amostras não maturadas e maturadas (7 dias) obtidas do músculo Longissimus lumborum. Resultados: Não houve diferenças significativas (p>0,05) entre os tratamentos para pH da carcaça e L* (luminosidade), a* (intensidade de vermelho), b* (intensidade de amarelo), força de cisalhamento, perdas por descongelamento, perdas por cocção, perdas totais e composição química da carne. O valor de b* da gordura subcutânea foi maior (p=0,03) em bovinos alimentados com dietas contendo grãos de milho, independentemente do tipo de processamento. O comprimento de sarcômero foi maior na carne maturada de novilhos alimentados com sorgo, independente do método de processamento (p=0,01). Conclusões: O método de processamento dos grãos não afetou a qualidade da carne bovina, no entanto, a cor da gordura subcutânea e o comprimento de sarcômero da carne maturada foram afetados pelo tipo de grão.

Prospects and Constraints of Transplanted Maize, Wheat, Sorghum and Pearl Millet: A Review

Cereal crops such as maize, wheat, sorghum and pearl millet are important for human consumption due to their nutritional benefits. These cereals play pivotal roles to meet world’s food demand. However, maintenance of food security particularly in the circumstance of changing climate, constantly urges for modification of agro-techniques and one such modification is the incorporation of transplanting technique in these cereals as an alternative under a non-practicable situation of direct sowing. Transplanting is a method of transferring seedlings grown in nursery or others to the field. It has been already found to shorten the crop duration and improve germination, plant stand, seed and seedling quality parameters, growth, yield and economic profitability of these cereals. Besides, research findings are also available stating that transplanting helps these cereals to cope up with vagaries of weather and to exhibit greater radiation and water use efficiencies and suppression of weeds. Outcomes of transplanting are however dependent on various factors like methods of nursery raising, the variety used, mode of planting, age of seedlings etc. In spite of these prospects, transplanting technique is not so popular in these cereals due to poor dissemination, discouraging research findings, pest and disease problems, lack of suitable package of practices etc. Therefore, focuses are to be given in conducting more and more research trials to confirm its location and situation wise efficacy and also in developing and disseminating a suitable package of practices of transplanting accordingly.

Transient expression of a green fluorescent protein in tobacco and maize chloroplast

BACKGROUND: Maize is one of the most important crops worldwide and has been a target of nuclear-based transformation biotechnology to improve it and satisfy the food demand of the ever-growing global population. However, the maize plastid transformation has not been accomplished due to the recalcitrant condition of the crop. RESULTS: In this study, we constructed two different vectors with homologous recombination sequences from maize (Zea mays var. LPC13) and grass (Bouteloua gracilis var. ex Steud) (pZmcpGFP and pBgcpGFP, respectively). Both vectors were designed to integrate into rrn23S/rrn16S from an inverted repeat region in the chloroplast genome. Moreover, the vector had the mgfp5 gene driven by Prrn, a leader sequence of the atpB gene and a terminator sequence from the rbcL gene. Also, constructs have an hph gene as a selection marker gene driven by Prrn, a leader sequence from rbcL gene and a terminator sequence from the rbcL gene. Explants of maize, tobacco and Escherichia coli cells were transformed with both vectors to evaluate the transitory expression­an exhibition of green and red fluorescent light under epifluorescence microscopy. These results showed that both vectors were expressed; the reporter gene in all three organisms confirmed the capacity of the vectors to express genes in the cell compartments. CONCLUSIONS: This paper is the first report of transient expression of GFP in maize embryos and offers new information for genetically improving recalcitrant crops; it also opens new possibilities for the improvement in maize chloroplast transformation with these vectors.

Toxicity of the essential oil of basil cultivars and hybrids and its repellent effect on stored grain pests / Toxicidade do óleo essencial de cultivares e híbridos de manjericão e seu efeito repelente sobre pragas de grãos armazenados

Essential oils have emerged as an alternative to synthetic insecticides in the control of stored grain pests. The toxicity and repellency of the essential oils of four basil cultivars and three basil hybrids and the monoterpenes linalool, citral, and (E)-methyl cinnamate were evaluated in the stored grain pests Callosobruchus maculatus and Sitophillus zeamais. The essential oils of the cultivar Genovese and the hybrid 'Genovese' x 'Maria Bonita' were more toxic to C. maculatus. Conversely, the essential oils of the cultivar Sweet Dani and the hybrid 'Cinnamom' x 'Maria Bonita' were more toxic to S. zeamais. Among the monoterpenes, (E)-methyl cinnamate was the most toxic to both pests, taking 0.14 and 0.34 µ L.mL-1 to kill 50% of the C. maculatus and S. zeamais populations, respectively. All essential oils from cultivars, hybrids, and monoterpenes were repellent to S. zeamais, except for (E)-methyl cinnamate. For C. maculatus, this effect was lower, being citral the most repellent compound. Results demonstrate the insecticidal potential of the essential oil of O. basilicum and its monoterpenes in the control of stored grain pests.

Os óleos essenciais surgem como alternativa aos inseticidas sintéticos no controle das pragas de grãos armazenados. A toxicidade e a repelência dos óleos essenciais de quatro cultivares e três híbridos de manjericão e dos monoterpenos linalol, citral e (E)-cinamato de metila foram avaliadas nas pragas de grãos armazenados Callosobruchus maculatus e Sitophillus zeamais. Os óleos essenciais da cultivar Genovese e do híbrido 'Genovese' x 'Maria Bonita' foram mais tóxicos para C. maculatus. Já para S. zeamais, os óleos essenciais das cultivar Sweet Dani e do híbrido 'Cinnamom' x 'Maria Bonita' apresentaram maior toxicidade. Dentre os monoterpenos, o (E)-cinamato de metila foi o mais tóxico para ambas as pragas. Foram necessários 0,14 e 0,34 µ L.mL-1 para matar 50% da população de C. maculatus e S. zeamais. Todos os óleos essenciais das cultivares, dos híbridos e dos monoterpenos foram repelentes a S. zeamais, com exceção do (E)-cinamato de metila. Já para C. maculatus, este efeito foi reduzido, sendo o citral o composto mais repelente. Nos resultados demonstram o potencial inseticida dos óleos essenciais de O. basilicum e seus monoterpenos para o controle de pragas de grãos armazenados.