First Report of Vascular Wilt on Peanut in Mexico Caused by Fusarium incarnatum.

During the fall of 2020, wilt symptoms were presented in a commercial peanut field (Arachis hypogaea L.), variety 'CHAMPS' in Buenavista de Benito Juárez, México (18.460501 N, 98.627100 W). A peanut field was scout 80 days after planting, and plants presenting symptoms of root and crown rot, vascular chlorosis, and tissue death, were sampled. Disease incidence was estimated at 55% of the field. Isolations of the pathogen were made from stem and root tissues. These samples were disinfected by immersion in 1% sodium hypochlorite (NaClO) for 3 min and immersion in 70% ethanol for 1 min with 3 rinses with sterile distilled water. Subsequently, 0.5 cm fragments were removed and placed on media of potato dextrose agar (PDA) and Rose Bengal. Petri dishes were incubated in complete darkness at 26 °C for 7 days. Abundant aerial white mycelium was observed, which turned tan to brown and showed a slightly orange color on the back of the plate. Finally, pure cultures were obtained by single sporing (Aslam et al. 2020). Colonies identified as Fusarium spp. (Leslie and Summerell, 2006) were sub cultured on PDA agar media and Spezieller Nährstoffarmer (Pérez-Vázquez et al. 2022) to observe microscopic characteristics of ten isolates. Colonies of a representative strain (MA-PET-03) produced hyaline septate hyphae, macroconidia dorsoventrally curved, tapering towards both ends of 51-57 × 4.6-5.4 µm (n = 80) with most having 7 septa. Microconidia were unicellular, nonseptate, hyaline, and ovoid, 12.4-20.6 × 3.6-4.1 µm (n = 80). Chlamydospores were abundant and globose 5-11 µm diam (n = 80), intercalary, and solitary in short chains (Figure 1). The observed microscopic characteristics correspond to the description of Fusarium incarnatum (Khoa et al. 2006; Leslie and Summerell, 2006; Xia et al. 2019). The molecular analyses were done with genomic DNA extracted as previously reported by Pérez et al. (2022). A region from the translation elongation factor gene was PCR amplified using EF688/EF1251 primers (Alves et al. 2008) and from the calmodulin (CMDA) gene, using CALDF1 and CALDR1 primers (Noel et al. 2022). The corresponding PCR products were purified with the Gen Elute™ PCR Clean-Up Kit from Sigma-Aldrich Co. (St. Louis Mo. USA) and sequenced at Macrogen Inc. (Seoul, South Korea). The phylogenetic analysis was inferred using the Bayesian Inference method with 1 million generations, final standard deviation was 0.008516. The nucleotide substitution model for Calmodulin (CMDA) was GTR + G and for TEF1 GTR + I + G. This analysis showed that strain MA-PET-03 shared 100% identity (Figure 2) with F. incarnatum ex-type strain CBS 132.73 (CMDA: MN170342; TEF1: JMN1704761) from Pointed gourd (Trichosanthes dioica) in Malawi Africa. The sequences of strain MA-PET-03 were deposited in GenBank (CMDA: OQ679820; TEF1: OQ679821). The pathogenicity tests were carried out with a total of 20 peanut plants, variety 'CHAMPS', 18 days after having been sown in groups of five seeds in 250 g plastic pots, containing a sterilized mixture of Peatmoss and Agrellite (1:1 v./v), with four repetitions. The seeds were inoculated by immersion in 20 mL of spore suspension (106 conidia/mL) isolated from F. incarnatum for 10 min. The plants were maintained in a greenhouse (70% relative humidity and 28 °C) until the appearance of disease symptoms of. Likewise, 10 control plants were inoculated with sterile water. The experiment was repeated twice. The symptoms developed 15 days after inoculation, the plants presented symptoms of chlorosis, wilting of leaves, stems, and roots, a manifestation similar to that observed in the field, while the control plants remained healthy. F. incarnatum was consistently reisolated from inoculated stems and roots and identified by the microscopic characteristics described above. Peanut leaf blight and wilt disease caused by F. incarnatum has been reported in India (Thirumalaisamy et al. 2019). This first report emphasizes that this phytopathogen is a new threat for peanut producers in Mexico, which is why our finding suggests the need to seek new strategies for its control.

[Ecological and biological benefits of the cosmopolitan fungus Trichoderma spp. in agriculture: A perspective in the Mexican countryside]. / Beneficios ecológicos y biológicos del hongo cosmopolita Trichoderma spp. en la agricultura: una perspectiva en el campo mexicano.

There is currently an extensive record of scientific studies on the general characteristics of filamentous fungus Trichoderma spp., which demonstrates its wide range of interrelation in ecosystems and its fungal activity that benefits the agricultural sector and agroindustry, as well as its importance in the preservation and restoration of the soil microbiota. The success of the biological and ecological benefits of Trichoderma is due to its reproductive capacity, as well as its efficiency in the use of soil nutrients; the efficacy of the genus has been reported against a variety of phytopathogenic fungi, as well as the potential to synthesize and release enzymes (cellulases, xylanases, and chitinases) that have been implemented in agroindustrial bioprocesses. It has also been reported that various species of Trichoderma spp. can produce auxins and gibberellin-type growth regulators, reported as growth promoters of some agricultural crops; however, their most relevant fact is their ability to prevail at certain doses of 'agrotoxic' active ingredients and contribute studies regarding processes for obtaining biofuel and bioremediation of the agricultural soil. In this overview, a general description of the current and relevant studies of the different subspecies of Trichoderma and their contribution in agriculture is made, presenting results obtained in vitro, in greenhouses and in the field. This analysis will serve as a starting point for future research in Mexico, specifically on the genus Trichoderma and its benefits for the Mexican countryside.

Improving the Shelf Life of Avocado Fruit against Clonostachys rosea with Chitosan Hybrid Films Containing Thyme Essential Oil.

Hass avocadoes are one of the most popular fruits consumed worldwide because of their nutritional and nutraceutical content. Nevertheless, these fruits are susceptible to phytopathogen attacks that decrease fruit quality during the postharvest period. Herein we present the results of the in situ fungistatic activity of four hybrid films (FT1−FT4) manufactured with chitosan and different concentrations of the essential oil of thyme (TvEO). The films were evaluated as biodegradable materials to prevent fruit decay triggered by Clonostachys rosea which is considered an emergent phytopathogen of this crop. The in situ fungistatic strength, spectroscopic properties (FT-IR), optical features (transmittance/opacity), and consistency obtained by microscopic analysis (SEM), indicated that the films FT3 and FT4 possessed the best physicochemical properties to protect Hass avocadoes against the soft rot produced by C. rosea. Avocadoes treated with the films FT3 and FT4 significantly (p < 0.01) conserved fruit firmness and nutritional composition (protein, fat, fiber, and reducing sugars) as well as the nutraceutical content (oleic, palmitoleic, linoleic, and palmitic acids) of infected avocados for 21 days. Our results validate the potential use of the films FT3 and FT4 to prevent the soft rot caused by C. rosea and to improve the shelf life of Hass avocadoes.

Evaluation of Genetic Parameters of Growth of Pelibuey and Blackbelly Sheep through Pedigree in Mexico.

Birth weight (BW) and weaning weight (WW) data from Pelibuey and Blackbelly lambs belonging to the Asociación Mexicana de Criadores de Ovinos (AMCO) were used with the objective of estimating genetic parameters (heritability and genetic correlations) and analyzing the growth characteristics of ewes born and weaned at different times of the same year from different herds with pedigree registration. In the case of Pelibuey lambs, the animal model included the weaning weight at 75 days of age, considering the direct additive genetic effect, maternal additive genetic effect, covariance between direct and maternal effects, as well as the permanent environmental effect of the mother. The direct estimators of heritability for Pelibuey were BW = 0.01 ± 0.021 and WW = 0.31 ± 0.074 and for Blackbelly they were BW = 0.05 ± 0.042 and WW = 0.41 ± 0.146. In the case of the maternal heritability estimators in Pelibuey they were BW = 0.02 ± 0.040 and WW = 0.21 ± 0.121 and for Blackbelly they were BW = 0.12 ± 0.054 and WW = 0.28 ± 0.121. The magnitude of the estimates of genetic correlations between direct and maternal effects for adjusted weaning weight at 75 days of age indicate that genetic progress may be slow in a breeding program. However, these selection results could be included in the short term in the breeding programs for the Pelibuey and Blackbelly breeds in Mexico, for livestock development in low-income rural areas.

Biological Control of Charcoal Rot in Peanut Crop through Strains of Trichoderma spp., in Puebla, Mexico.

Charcoal rot is an emerging disease for peanut crops caused by the fungus Macrophomina phaseolina. In Mexico, peanut crop represents an important productive activity for various rural areas; however, charcoal rot affects producers economically. The objectives of this research were: (a) to identify and morphologically characterize the strain "PUE 4.0" associated with charcoal rot of peanut crops from Buenavista de Benito Juárez, belonging to the municipality of Chietla in Puebla, Mexico; (b) determine the in vitro and in vivo antagonist activity of five Trichoderma species on M. phaseolina, and (c) determine the effect of the incidence of the disease on peanut production in the field. Vegetable tissue samples were collected from peanut crops in Puebla, Mexico with the presence of symptoms of charcoal rot at the stem and root level. The "PUE 4.0" strain presented 100% identity with M. phaseolina, the cause of charcoal rot in peanut crops from Buenavista de Benito Juárez. T. koningiopsis (T-K11) showed the highest development rate, the best growth speed, and the highest percentage of radial growth inhibition (PIRG) over M. phaseolina (71.11%) under in vitro conditions, in addition, T. koningiopsis (T-K11) showed higher production (1.60 ± 0.01 t/ha-1) and lower incidence of charcoal rot under field conditions. The lowest production with the highest incidence of the disease occurred in plants inoculated only with M. phaseolina (0.67 ± 0.01 t/ha-1) where elongated reddish-brown lesions were observed that covered 40% of the total surface of the main root.

First report of Xanthomonas campestris pv. campestris as the causal agent of necrotic leaf spot in Phaseolus vulgaris at Puebla, Mexico.

Beans are the most cultivated legume in the world. In Mexico, it is the second most important crop after corn (FAO 2020; SIAP 2020). Bean plants "Flor de Mayo M38" variety were affected by a foliar disease during the agricultural cycle 2019 in Puebla-Mexico (19°02'46.6" LN and 98°05'15.6" LO). Necrotic V- shaped lesions were observed on the margins of the leaves surrounded by yellow halos followed by foliar necrosis, affecting 40% of the crop. In Mexico this variety of cultivars is in great demand for local consumption and generates income in foreign currency (Castellanos et al. 1997). Sampling was carried out on 50 plants "Flor de Mayo M38" variety, with necrotic leaf symptoms from ten plots of one hectare. Samples were cut into pieces (5 mm), disinfested with 1% hypochlorite 3 min, and washed with sterile distilled water. Subsequently, samples were dried on sterile paper and placed on Petri plates containing yeast extract calcium carbonate dextrose agar (YDC) medium and kept at 36°C for 3 days. Colonies of ten typical bacteria isolated from all symptomatic plants were Gram (-), small and uniform in size with rounded edges, yellow, convex with entire borders and mucoid appearance on YDC. Bacteria did not grow on 0.1% triphenyl tetrazolium chloride amended casamino acid, peptone, and glucose medium (CPG). Biochemical tests showed that isolates did not reduce nitrate to nitrites, had positive catalase and starch hydrolysis, while the Kovac oxidase test was negative (Schaad and White 1974). Genus identity of the representative isolate Xcf1-APJR, was confirmed by 16S rRNA encoding gene partial sequencing, using universal primers 518F (5'-CCAGCAGCCGCGGTAATACG-3') and 800R (5'-TACCAGGGTATCTAATCC-3') (Halim et al. 2020). BLASTn alignments against the nucleotide collection were 100% identical to Xanthomonas sequences including Xanthomonas campestris pv. campestris strains NZ_AP019684.1, CP025750.1, and MN108237.1. The 1,418 bp sequence was deposited in the GenBank database under accession number MT645246. The identification of species/pathovar was accomplished by serological methods using a polyclonal antiserum specific for X. campestris pv. campestris (Popovic ́ et al. 2013) with the DAS-ELISA commercial kit (catalog number 07122C/096, LOEWE Biochemica GmbH, Germany). The pathogenicity test was carried out on 50 healthy bean plants from the "Flor de Mayo M38" variety. Bacterial culture incubated at 28°C for 48 h in YDC medium was used to prepare the bacterial suspension (108 CFU mL-1). The first two lower leaves of 30-day-old plants were inoculated by sprinkling. Ten plants sprayed with sterile distilled water were used as negative control. All plants were kept for 20 days in greenhouse at 18-26°C and relative humidity of 60%. After seven days, chlorotic lesions developed on all inoculated plants that became necrotic from 14 days after inoculation (dai). Necrotic leaf spots merged at 14 dai to form necrotic areas of more than 20 mm in diameter, reaching total necrosis of the leaf tissue at 20 dai and were similar to the symptoms observed in the field. Koch's postulates were confirmed by the reisolation of Xcf1-APJR strain, which presented the same colony morphology, partial sequence, and polyclonal specific detection. This is the first report of this pathogen causing necrotic leaf spot in beans from the "Flor de Mayo M38" variety in Puebla-Mexico. The author(s) declare no conflict of interest. References: FAO. 2020. FAOSTAT. Food and Agriculture Data. http://www.fao.org/faostat/en/#home/. SIAP. 2020. Atlas Agroalimentario. https://www.gob.mx/siap/. Castellanos, J. Z., et al. 1997. Arch. Latinoam. Nutr. 47:163. Schaad, N. W., and White, W. C. 1974. Phytopathology. 64:876. https://doi.org/10.1094/Phyto-64-876 Halim, R. A., et al. 2020. HAYATI J. Biosciences. 27:215. https://doi.org/10.4308/hjb.27.3.215 Popovic ́, T., et al. 2013. Plant Dis. 97:418. https://doi.org/10.1094/PDIS-05-12-0506-PDN.

First Report of Macrophomina phaseolina Causing Charcoal Rot of Peanut (Arachis hypogaea L.) in Mexico.

Peanut (Arachis hypogaea L.) is the third most important oilseed crop in the world. The cultivated area in Mexico is currently 52,046 ha with a production of 91,109 ton in 2018 (FAO, 2020). Puebla state ranks third in the national production with 9,313 ton (SIAP, 2020). In September 2019, typical symptoms of charcoal rot (Macrophomina phaseolina (Tassi) Goid.) were observed in about 50% of cultivar Virginia Champs peanuts, and it affecting 1.5 ha located in Chietla (18° 27' 39" N; 98° 37' 11" W), Puebla, Mexico. Diseased plants showed brown discoloration in stem and root rot, with chlorotic foliage, dark microsclerotia were observed on the stem and premature dying. To isolate the causal agent of these symptoms, 20 infected plants were recovered and processed in the laboratory. Ten pieces of stem and root tissue were selected from each plant, cut into small pieces 5-mm in length, superficially disinfested with 1% sodium hypochlorite for 3 min, followed by three rinses with sterile distilled water. Later, dried on sterile paper and placed on Petri plates containing potato dextrose agar (PDA) medium, which were kept at 28°C for 7 days (12 h light and 12 h dark). Four colonies were purified via hyphal tip culture, fungus was consistently isolated from the analyzed tissues; additional microcultures were prepared to observe phenotypic characteristics. Colonies showed dense growth, with a gray initial mycelium, becoming black after 7 days. Microesclerotia with spherical to oblong in shape were observed after 5 days on PDA, with a black coloration, measuring an average of 74 µm width × 110 µm length (n=40). Phylogenetic analysis was conducted by amplification and sequencing of the internal transcribed spacer (ITS) region with the ITS5 and ITS4 primers (White et al. 1990). The obtained sequences were deposited in GenBank database under accession numbers: MW585378, MW585379, MW585380, and MW585381 containing approximately 601 bp of the ITS1-5.8S-ITS2 region (complete sequence); they were 99% identical with the reference sequence of Macrophomina phaseolina (GenBank accession KF951698) isolated in Phaseolus vulgaris from Mexico. Based on the symptoms in the field, colony morphology, color, and shape of the microsclerotia, and molecular identification, the fungus was identified as M. phaseolina (Tassi) Goid. The pathogenicity test was performed on peanut plants cultivar Virginia Champs grown on plastic pots with an autoclaved peat/soil mixture under greenhouse conditions (70% relative humidity and 28°C). Fifty two-month-old peanut plants were inoculated using the toothpick method. The toothpicks were previously sterilized and then placed in Petri plates with each of the four colonies of M. phaseolina until colonization. Small wounds were made with those toothpicks in the roots, and a sterile toothpick was used in the control plants, the assays were performed twice. After three weeks, the inoculated plants exhibited symptoms of wilting chlorosis on the leaves and brown to dark brown discoloration of the vascular ring, while control plants remained healthy. M. phaseolina was re-isolated from symptomatic root tissues and identified by phylogenetic approach, fulfilling Koch's postulates. To date, this fungus affects at least 372 hosts globally causing yield losses. Although in Mexico this fungus has been documented in Glycine max, Ipomoea batatas, Phaseolus vulgaris, Physalis ixocarpa, Saccharum officinarum, Sesamum indicum, Solanum melongena, S. tuberosum, and Sorghum bicolor (Farr and Rossman 2021). However, there are no reports of M. phaseolina as a potential pathogen on peanut; therefore, according to our knowledge, this is the first report of this fungus affecting A. hypogaea in Mexico.

Endophytic Trichoderma Species Isolated from Persea americana and Cinnamomum verum Roots Reduce Symptoms Caused by Phytophthora cinnamomi in Avocado.

Avocado root rot caused by the oomycete Phytophthora cinnamomi is a severe disease that affects avocado production in Mexico and worldwide. The use of biological control agents such as Trichoderma species isolated from places where the disease is always present, represents an efficient alternative to reduce losses. Thus, the objective of this research was to evaluate the biocontrol ability of 10 endophytic Trichoderma spp. strains against P. cinnamomi tested both in vitro and in the greenhouse. The endophytic Trichoderma spp. were recovered from Persea americana and Cinnamomum verum roots, isolated and purified on potato-dextrose-agar medium. Ten strains were identified by phylogenetic reconstruction of the internal transcribed spacer region of rDNA sequences as T. asperellum (T-AS1, T-AS2, T-AS6, and T-AS7), T. harzianum (T-H3, T-H4, and T-H5), T. hamatum (T-A12), T. koningiopsis (T-K8 and T-K11), and P. cinnamomi (CPO-PCU). In vitro dual-culture assay, the percentage of inhibition of radial growth (PIRG) between Trichoderma spp. and P. cinnamomi strains was measured according to the Bell's scale. PIRG results indicated that T-AS2 reached the highest value of 78.32%, and T-H5 reached the lowest value of 38.66%. In the greenhouse, the infection was evaluated according to the percentage of disease incidence. Plants with the lowest incidence of dead by avocado root rot were those whose seedlings were inoculated with T-AS2 and T-AS7, resulting in only 5% death by root rot caused by P. cinnamomi. The disease incidence of seedlings with wilt symptoms and death decreased more than 50% in the presence of Trichoderma spp. Relying on the results, we conclude that T. asperellum and T. harzianum contribute to the biocontrol of soil-borne pathogenic oomycete P. cinnamomi.

Chemical Variation and Pharmacological Properties of Dyssodia decipiens Essential Oil.

Dyssodia decipiens is one of the seven recognized species within the Dyssodia genus, which has economic and social relevance in Mexico. Herein, we report on the volatile characterization and pharmacological activity of D. decipiens. The essential oils (2017-2019) contained verbenone (30.8-60.9 %), limonene (5.6-35.5 %), ß-caryophyllene (7.8-19.8 %) and linalool (4.5-12.4 %) as major constituents along the studied years. Antifungal properties were probed on Candida albicans ATCC 90028, ATCC 10231 (fluconazole resistant) and five clinical isolates (IS1-IS5). Flower essential oils had the best anti-C. albicans activity (MIC 59.2-93.5 µg mL-1 ), and limonene (MIC 125.5-188.4 µg mL-1 ) and ß-caryophyllene (MIC 104.3-184.2 µg mL-1 ) were involved in this effect. SEM examination revealed that D. decipiens essential oils produced an evident lysis on the fungus. Mosquito repellent activity was demonstrated on Aedes aegypti, a vector of dengue, chikungunya and zika viruses. The repellent activity of leaf essential oils (20 %) was effective within 1-5 h post-treatment (>90 %) and it was stronger (p<0.01) than that of commercial DEET. The evaluation of the four major volatiles (10 % each) produced similar results to those of essential oils. Finally, leaf essential oils showed a moderate antiproliferative activity on the lines OVCAR-3 (LD50 56.5-85.7 µg mL-1 ), and verbenone (LD50 65.3 µg mL-1 ) and ß-caryophyllene (LD50 43.6 µg mL-1 ) were linked to this effect.

Diversidad de Vanilla spp. (Orchidaceae) y sus perfiles bioclimáticos en México / Diversity and bioclimatic profiles of Vanilla spp. (Orchidaceae) in Mexico

Resumen: El género Vanilla comprende alrededor de 110 especies, distribuidas en las partes tropicales del mundo, y es el continente americano donde se encuentra la mayor cantidad de especies reportadas. En México, el cultivo de la vainilla está relacionado con diversas culturas como la totonaca, maya, chinanteca, mazateca, entre otras. En la actualidad, este cultivo presenta factores condicionantes tales como: técnicos, económicos, sociales, ecológicos y climáticos, que limitan su producción y la conservación de especies silvestres y cultivadas, por lo que es necesario, conocer su estado actual, en relación con su diversidad, así como algunos de los principales indicadores del perfil bioclimático de cada una de las especies, que ayuden en la toma de decisiones para su conservación y mejoramiento genético. Durante 2008, se realizaron consultas a herbarios de IPN, MEXU, XAL, base de datos de la Red Mundial de Información sobre la Biodiversidad de la CONABIO (REMIB), Global Biodiversity Information Facility (GBIF) y datos de accesiones vivas del banco de germoplasma de vainilla de la BUAP, formado del 2008 al 2014. Se realizaron mapas de distribución mediante un sistema de información geográfica. Se obtuvo el perfil bioclimático de cada especie considerando 19 variables de World Clim, y altitud a una resolución espacial de aproximadamente 1 Km2. Se calcularon las medias, desviaciones estándar y varianzas de las 19 variables en cada uno de los puntos registrados. Se obtuvieron los intervalos de las condiciones ambientales extremas (mínimo, promedio y máximo) para cada una de las especies de vainilla. Para determinar las variables de mayor importancia en la distribución de las especies se realizó un análisis de componentes principales, y a las variables que resultaron significativas se les realizó pruebas de Kruskal-Wallis y Dunn. Los resultados indicaron que en México se tienen registros de V. planifolia, V. pompona, V. insignis, V. inodora V. odorata, V. cribbiana y V. sprucei distribuidas en nueve estados. V. planifolia presentó intervalos amplios de temperatura y precipitación; V. pompona, V. odorata, V. insignis y V. inodora tuvieron intervalos intermedios. La amplitud de los datos extremos de cada especie puede considerarse para ubicar los sitios donde se puedan llevar a cabo estrategias regionales de conservación ex situ y el establecimiento de cultivos. El perfil bioclimático encontrado permite inferir de manera indirecta la condición genética de cada especie que podría ser utilizada en programas de mejoramiento genético como: la alta altitud y tolerancia a bajas temperaturas (V. odorata), la tolerancia a altas temperaturas (V. inodora) y tolerancia a baja precipitación (V. odorata, V. pompona y V. planifolia).

Abstract: The genus Vanilla comprises around 110 species distributed throughout Earth's tropical regions, with the largest number of reported species growing in the American continent. Vanilla farming is associated with many Mexican cultures such as the Totonac, Mayan, Chinantec, and Mazatec, among others. Currently, this crop is threatened by technical, social, ecological, and climatic conditioning factors, limiting its production and the preservation of wild and cultivated species. It is therefore necessary to ascertain the current diversity status of each of these species, as well as some of their main bioclimatic profile indicators, in order to help decision-making, aimed at preserving and genetically improve these species. During 2008, we gathered data from IPN, MEXU, and XAL herbaria, as well as from CONABIO's World Information Network on Biodiversity (REMIB), the Global Biodiversity and Information Facility (GBIF), and we also used data from live access to BUAP's vanilla germplasm bank, obtained between 2008 and 2014. Distribution maps were generated using a geographical information system. Bioclimatic profiles for each species were obtained considering 19 WorldClim variables and altitude at a spatial resolution of approximately 1 Km2. Variance, Mean, and standard deviation for each of the 19 variables were calculated at each of the registered points. Extreme environmental condition intervals (minimum, average, and maximum) were also obtained. In order to determine the most important distribution variables of the species, we performed a principal component analysis and carried out Kruskal-Wallis and Dunn's tests on the variables identified as significant. Results indicated records for V. planifolia, V. pompona, V. insignis, V. inodora V. odorata, V. cribbiana, and V. sprucei in Mexico, distributed throughout nine states in the country. V. planifolia presented wide intervals of temperature and rain precipitation, while V. pompona, V. odorata, V. insignis and V. inodora presented intermediate intervals. The amplitudes of extreme data for each species can be considered in locating areas where ex situ regional preservation strategies could be put in place, as well as in establishing areas for cultivation. The bioclimatic profile we found, allows for an indirect inference of each species' genetic condition, which could be used in genetic improvement programs; for instance, V. odorata grows at high altitudes and tolerates low temperatures, while V. inodora tolerates high temperatures, and V. odorata, V. pompona and V. planifolia tolerate low rain precipitation. Rev. Biol. Trop. 65 (3): 975-987. Epub 2017 September 01.

Oclusión de haces vasculares para evaluar resistencia de caña de azúcar a xanthomonas albilineans / Vascular bundle occlusion as a measure of sugarcane resistance to xanthomonas albilineans / Oclusão de feixes vasculares para avaliar resistência de cana de açucar a xanthomonas albilineans

La evaluación de resistencia de caña de azúcar (Saccharum officinarum L.) a escaldadura de la hoja ha sido realizada sin consideración del porcentaje de daño al sistema vascular. En el presente estudio se analizó la oclusión de haces vasculares del tallo, en la parte basal y apical de la caña de azúcar, para evaluar resistencia a Xanthomonas albilineans (Xa). Se utilizó caña de azúcar de la variedad susceptible Mex 64-1487 y la resistente Co 997, distribuidas en un diseño de bloques al azar con cuatro repeticiones. La inoculación se realizó por inyección en la parte media del tallo de plantas de tres meses de edad, con 3ml de Xa con 2x10(5)UFC/ml o agua estéril. Los muestreos se realizaron a 0, 30, 60, 110 y 213 días después de la inoculación (ddi), cortando dos tallos al azar por repetición. De cada tallo se tomó un nudo de la parte basal y otro de la parte apical, los cuales se colocaron en formaldehido-alcohol-ácido acético. La oclusión se analizó utilizando un diseño completamente al azar con arreglo factorial 2³ con tres repeticiones. La identificación de Xa se realizó utilizando Bio-PCR (colonias bacterianas en la PCR), con los iniciadores PGBL1 y PGBL2, específicos para DNA de Xa. El mayor porcentaje de haces vasculares ocluidos se detectó a los 110 ddi en la parte basal (p£0,05) de ambas variedades. La oclusión de haces vasculares permitió evaluar correctamente la resistencia de Mex 64-1487 y Co 997(p£0,05) utilizando la parte basal del tallo.

The sugarcane (Saccharum officinarum L.) resistance to leaf scald has been studied without consideration of the percentage of damage to the vascular system. In the present study the occlusion of vascular bundles in the basal and apical parts of the sugarcane stalk was analyzed to evaluate the resistance to Xanthomonas albilineans (Xa). The susceptible sugarcane variety Mex 64-1487 and the resistant variety Co 997 were used under a randomized design with four replications. Inoculation was carried out by injection in the middle of the stalk of 3 month old plants, using 3ml of a 2x10(5)UFC/ml bacterial suspension or sterile water. The sampling was done at 0, 30, 60, 110 and 213 days after the inoculation, cutting two stalks by replication. In each plant two nodes from the basal part and two from the apical part were sampled and kept in a formaldehide-alcohol-acetic acid solution, to determine occlusion with a complete randomized design in factorial composition 2³ with three replications. The Xa diagnosis was done employing Bio-PCR (bacterial cells in the PCR) and PGBL1 and PGBL2 DNA specific primers for Xa. The percentage of vascular bundle occlusion was larger in the basal part of the stalk in both varieties (p£0,05). The determination of the vascular bundle occlusion allowed a correct evaluation of the resistance of both Mex 64-1487 and Co 997 (p£0,05), analyzing the lower basal part of the stalk.

A avaliação de resistência de cana de açucar (Saccharum officinarum L.) a escaldadura da folha tem sido realizada sem consideração da porcentagem de dano ao sistema vascular. No presente estudo se analisou a oclusão de feixes vasculares do caule, na parte basal e apical da cana de açucar, para avaliar resistência a Xanthomonas albilineans (Xa). Utilizou-se cana de açucar da variedade suscetível Mex 64-1487 e a resistente Co 997, distribuidas em um desenho aleatório de blocos com quatro repetições. A inoculação se realizou por injeção na parte média do caule de plantas de três meses de idade, com 3ml de Xa com 2x10(5)UFC/ml ou agua estéril. As amostragens foram realizdas a 0, 30, 60, 110 e 213 dias após a inoculação (dai), cortando dois caules aleatoriamente por repetição. De cada caule foi retirado um nó da parte basal e outro da parte apical, os quais foram colocados em formaldehido-álcool-ácido acético. A oclusão se analisou utilizando um desenho completamente aleatório com arranjo fatorial 2³ com três repetições. A identificação de Xa se realizou utilizando Bio-PCR (colônias bacterianas na PCR), com os iniciadores PGBL1 e PGBL2, específicos para DNA de Xa. A maior porcentagem de feixes vasculares ocluídos foi detectada aos 110 dai na parte basal (p£0,05) de ambas as variedades. A oclusão de feixes vasculares permitiu avaliar corretamente a resistência de Mex 64-1487 e Co 997(p£0,05) utilizando a parte basal do caule.