Participación del transporte simplástico de las auxinas durante el desarrollo de las plantas / Symplastic transport participation of auxins during plant development

Resumen: La apropiada organogénesis de las plantas, durante su ciclo de vida, propicia su desarrollo y la adaptación a diferentes condiciones am bientales. Diversas fitohormonas regulan el desarrollo vegetal, pero la auxina denominada ácido indol-3-acético (AIA) es una de las más importantes. El AIA se sintetiza en la parte aérea de la planta y se moviliza a los tejidos demandantes por un transporte rápido que utiliza el floema y por el transporte polar de auxinas (TPA). Recientemente, se ha demostrado que las auxinas también se movilizan mediante el transporte simplástico (TS) a través de los plasmodesmos (PD), cuya apertura o cierre está regulada respectivamente por la degradación o la deposición de la callosa. El objetivo del presente trabajo fue profundizar en los avances sobre la participación del transporte simplástico de las auxinas durante el desarrollo vegetal, así como la degradación o deposición de la callosa, en el cierre o apertura de los PD, para regular el desarrollo de algunos órganos de Arabidopsis thaliana. La intervención de las proteínas PDLP5 es determinante para la deposición de la callosa en los PD, lo que regula la distribución de la auxina e impacta en la formación radicular, especialmente en las raíces laterales. La participación del TS es importante para desarrollar la actividad de las auxinas, lo cual favorece la formación radicular, necesaria en la mejora de absorción de nutrientes de las plantas. Este conocimiento puede ser utilizado para mejorar las plantas de interés agronómico.

Abstract: The appropriate organogenesis of plants during their life cycle promotes their development and adaptation to different environmental conditions. Various phytohormones regulate plant development but auxin, called Indole-3-Acetic Acid (IAA), is one of the most important. IAA is synthesized in the aerial part of plant and is mobilized to the demanding tissues by a rapid transport using the phloem and by the polar auxin transport (PAT). Recently, it has been shown that auxins also are mobilized by a symplastic transport (ST) through plasmodesmata (PD), which opening or closing is regulated by the callose degradation or deposition respectively. The objective of the present work was to deepen the analysis on the participation of symplastic transport of auxins during plant development, as well in the callose degradation or deposition, in the closing or opening of the PD, that regulates the development of some organs of Arabidopsis thaliana. The intervention of PDLP5 proteins is decisive for the callose deposition in the PD, which regulates the auxin distribution and impacts root formation, especially at the lateral roots. The participation of TS is important to develop the auxin activity, which favors root formation, necessary for the improvement plant nutrient absorption. This knowledge can be used to improve development plants of agronomic interest.

Comparative transcriptome analysis of high- and low-embryogenic Hevea brasiliensis genotypes reveals involvement of phytohormones in somatic embryogenesis.

BACKGROUND: Rubber plant (Hevea brasiliensis) is one of the major sources of latex. Somatic embryogenesis (SE) is a promising alterative to its propagation by grafting and seed. Phytohormones have been shown to influence SE in different plant species. However, limited knowledge is available on the role of phytohormones in SE in Hevea. The anther cultures of two Hevea genotypes (Yunyan 73477-YT and Reken 628-RT) with contrasting SE rate were established and four stages i.e., anthers (h), anther induced callus (y), callus differentiation state (f), and somatic embryos (p) were studied. UPLC-ESI-MS/MS and transcriptome analyses were used to study phytohormone accumulation and related expression changes in biosynthesis and signaling genes. RESULTS: YT showed higher callus induction rate than RT. Of the two genotypes, only YT exhibited successful SE. Auxins, cytokinins (CKs), abscisic acid (ABA), jasmonic acid (JA), salicylic acid (SA), gibberellins (GAs), and ethylene (ETH) were detected in the two genotypes. Indole-3-acetic acid (IAA), CKs, ABA, and ETH had notable differences in the studied stages of the two genotypes. The differentially expressed genes identified in treatment comparisons were majorly enriched in MAPK and phytohormone signaling, biosynthesis of secondary metabolites, and metabolic pathways. The expression changes in IAA, CK, ABA, and ETH biosynthesis and signaling genes confirmed the differential accumulation of respective phytohormones in the two genotypes. CONCLUSION: These results suggest potential roles of phytohormones in SE in Hevea.

Parthenocarpy-related genes induced by naphthalene acetic acid in oil palm interspecific O × G [Elaeis oleifera (Kunth) Cortés × Elaeis guineensis Jacq.] hybrids.

Parthenocarpy is the development without fertilization of seedless fruits. In the oil palm industry, the development of parthenocarpic fruits is considered an attractive option to increase palm oil production. Previous studies have shown the application of synthetic auxins in Elaeis guineensis, and interspecific O×G hybrids (Elaeis oleifera (Kunth) Cortés × E. guineensis Jacq.) induces parthenocarpy. The aim of this study was to identify the molecular mechanism through transcriptomics and biology system approach to responding to how the application of NAA induces parthenocarpic fruits in oil palm O×G hybrids. The transcriptome changes were studied in three phenological stages (PS) of the inflorescences: i) PS 603, pre-anthesis III, ii) PS 607, anthesis, and iii) PS 700, fertilized female flower. Each PS was treated with NAA, Pollen, and control (any application). The expression profile was studied at three separate times: five minutes (T0), 24 hours (T1), and 48 h post-treatment (T2). The RNA sequencing (RNA seq) approach was used with 27 oil palm O×G hybrids for a total of 81 raw samples. RNA-Seq showed around 445,920 genes. Numerous differentially expressed genes (DEGs) were involved in pollination, flowering, seed development, hormone biosynthesis, and signal transduction. The expression of the most relevant transcription factors (TF) families was variable and dependent on the stage and time post-treatment. In general, NAA treatment expressed differentially more genes than Pollen. Indeed, the gene co-expression network of Pollen was built with fewer nodes than the NAA treatment. The transcriptional profiles of Auxin-responsive protein and Gibberellin-regulated genes involved in parthenocarpy phenomena agreed with those previously reported in other species. The expression of 13 DEGs was validated by RT-qPCR analysis. This detailed knowledge about the molecular mechanisms involved in parthenocarpy could be used to facilitate the future development of genome editing techniques that enable the production of parthenocarpic O×G hybrid cultivars without growth regulator application.

Hormone released by the microalgae Neochlorisaquatica and alkalinization influence growth of terrestrial and floating aquatic plants.

The microalgae Neochloris aquatica were previously evaluated as a potential biological control agent and source of bioactive compounds against immature stages of Culex quinquefasciatus. Larvae reared on microalgae suspension showed mortality or drastic effects with morphological alterations and damage in the midgut. N. aquatica have nutritional and toxic effects, resulting in delayed life cycle and incomplete adult development. Given the possibility of its use as a biological control agent, in this work we evaluate the effect of microalgae on other organisms of the environment, such as plants. Arabidopsis thaliana, a terrestrial plant, and Lemna sp., a floating aquatic plant, were selected as examples. Interaction assays and compound evaluations showed that the microalgae release auxins causing root inhibition, smaller epidermal cells and hairy root development. In Lemna sp., a slight decrease in growth rate was observed, with no deleterious effects on the fronds. On the other hand, we detected a detrimental effect on plants when interactions were performed in a closed environment, in a medium containing soluble carbonate, in which microalgae culture rapidly modifies the pH. The experiments showed that alkalinization of the medium inhibits plant growth, causing bleaching of leaves or fronds. This negative effect in plants was not observed when plants and microalgae were cultured in carbonate-free media. In conclusion, the results showed that N. aquatica can modify plant growth without being harmful, but the rapid alkalinization produced by carbon metabolism of microalgae under CO2-limiting conditions, could regulate the number of plants.

Multiplication, morphogenesis and foliar abscision of Schinopsis brasiliensis Engl. in vitro / Multiplicación, morfogénesis y abscisión foliar de Schinopsis brasiliensis Engl. in vitro

The objective was to evaluate plant growth regulators and ethylene inhibitors on the development and leaf abscission of Schinopsis brasiliensis Engl. Zeatin (ZEA) was evaluated in concentrations combined with concentrations of indolacetic acid (IAA), naphthalene acetic acid (NAA) and indolbutyric acid (IBA). ZEA and 6-benzylamino purine (BAP) were evaluated in concentrations plus a control. Ethylene inhibitors, silver nitrate and cobalt chloride were evaluated in four concentrations. The addition of 0.2 µL-1 of NAA to 0.4 µL-1 of ZEA promotes a greater number of baraúna sprouts. At concentrations of 5 and 10 µM, cobalt chloride is more efficient than silver nitrate for reducing leaf abscission in baraúna. IAA is the most suitable auxin to be associated with ZEA for higher shoot length and number of buds. Silver nitrate from a concentration of 20 µM completely avoids leaf abscission whilecobalt chloride has a maximum reduction in abscission at a concentration of 40 µM.

El objetivo fue evaluar reguladores de crecimiento e inhibidores de etileno sobre el desarrollo y abscisión foliar en Schinopsis brasiliensis Engl. La zeatina (ZEA) se evaluó en concentraciones combinadas con concentraciones de ácido indolacético (IAA), ácido naftaleno acético (NAA) y ácido indolbutírico (IBA). Se evaluaron ZEA y 6-bencilamino purina (BAP) en concentraciones más un control. Se evaluaron inhibidores de etileno, nitrato de plata y cloruro de cobalto, en cuatro concentraciones. La adición de 0.2 µL-1 de NAA a 0.4 µL-1 de ZEA promueve un mayor número de brotes de baraúna. A concentraciones de 5 y 10 µM, el cloruro de cobalto es más eficaz que el nitrato de plata para reducir la abscisión de las hojas en baraúna. IAA es la auxina más adecuada para asociar con ZEA para una mayor longitud de brotes y número de brotes. El nitrato de plata a partir de una concentración de 20 µM evita completamente la abscisión de las hojas, mientras que el cloruro de cobalto tiene una reducción máxima en la abscisión a una concentración de 40 µM.

Soybean injury caused by the application of subdoses of 2,4-D or dicamba, in simulated drift.

2,4-D or dicamba can cause injuries and other deleterious effects on non-tolerant soybeans. Thus, the objective was to evaluate the potential for injury of subdoses of 2,4-D or dicamba, in drift simulation, for application in non-tolerant soybeans. Two experiments were carried out, one with 2,4-D and the other with dicamba. The treatments consisted of the application, in post-emergence of non-tolerant soybean, of subdoses 0; 1.35; 2.68; 5.37; 10.72; 21.45 and 42.9 g acid equivalent (ae) ha-1 2,4-D choline salt or dicamba diglycolamine (DGA) salt. Injury symptoms in plants, plant height and yield were evaluated, and the results were subjected to regression analysis. Polynomial fit was possible for the doses of both herbicides, with deleterious effects on soybean, with reductions in height and yield. The application of 2,4-D ≥ 10.72 g ae ha-1 was enough to cause injuries greater than 10% in plants, in simulated drift. The application of dicamba ≥1.35 g ae ha-1 was enough to cause injuries greater than 30% in plants, in simulated drift. For both herbicides, greater potential for injury and reductions in soybean yield were observed for the application of the highest doses (21.45 and 42.9 g ae ha-1).

Transcriptome Dynamics of Rooting Zone and Leaves during In Vitro Adventitious Root Formation in Eucalyptus nitens.

Wood properties and agronomic traits associated with fast growth and frost tolerance make Eucalyptus nitens a valuable forest alternative. However, the rapid age-related decline in the adventitious root (AR) formation (herein, meaning induction, initiation, and expression stages) limits its propagation. We analyzed transcriptomic profile variation in leaves and stem bases during AR induction of microcuttings to elucidate the molecular mechanisms involved in AR formation. In addition, we quantified expressions of candidate genes associated with recalcitrance. We delimited the ontogenic phases of root formation using histological techniques and Scarecrow and Short-Root expression quantification for RNA sequencing sample collection. We quantified the gene expressions associated with root meristem formation, auxin biosynthesis, perception, signaling, conjugation, and cytokinin signaling in shoots harvested from 2- to 36-month-old plants. After IBA treatment, 702 transcripts changed their expressions. Several were involved in hormone homeostasis and the signaling pathways that determine cell dedifferentiation, leading to root meristem formation. In part, the age-related decline in the rooting capacity is attributable to the increase in the ARR1 gene expression, which negatively affects auxin homeostasis. The analysis of the transcriptomic variation in the leaves and rooting zones provided profuse information: (1) To elucidate the auxin metabolism; (2) to understand the hormonal and signaling processes involved; (3) to collect data associated with their recalcitrance.

The source, level, and balance of nitrogen during the somatic embryogenesis process drive cellular differentiation.

Since the discovery of somatic embryogenesis (SE), it has been evident that nitrogen (N) metabolism is essential during morphogenesis and cell differentiation. Usually, N is supplied to cultures in vitro in three forms, ammonium (NH4+), nitrate (NO3-), and amino N from amino acids (AAs). Although most plants prefer NO3- to NH4+, NH4+ is the primary form route to be assimilated. The balance of NO3- and NH4+ determines if the morphological differentiation process will produce embryos. That the N reduction of NO3- is needed for both embryo initiation and maturation is well-established in several models, such as carrot, tobacco, and rose. It is clear that N is indispensable for SE, but the mechanism that triggers the signal for embryo formation remains unknown. Here, we discuss recent studies that suggest an optimal endogenous concentration of auxin and cytokinin is closely related to N supply to plant tissue. From a molecular and biochemical perspective, we explain N's role in embryo formation, hypothesizing possible mechanisms that allow cellular differentiation by changing the nitrogen source.

Auxin-Cytokinin Cross Talk in Somatic Embryogenesis of Coffea canephora.

Cytokinins (CK) are plant growth regulators involved in multiple physiological processes in plants. One less studied aspect is CK homeostasis (HM). The primary genes related to HM are involved in biosynthesis (IPT), degradation (CKX), and signaling (ARR). This paper demonstrates the effect of auxin (Aux) and CK and their cross talk in a Coffea canephora embryogenic system. The transcriptome and RT-qPCR suggest that Aux in pre-treatment represses biosynthesis, degradation, and signal CK genes. However, in the induction, there is an increase of genes implicated in the CK perception/signal, indicating perhaps, as in other species, Aux is repressing CK, and CK are inducing per se genes involved in its HM. This is reflected in the endogenous concentration of CK; pharmacology experiments helped study the effect of each plant growth regulator in our SE system. We conclude that the Aux-CK balance is crucial to directing somatic embryogenesis in C. canephora.

Optimization and validation of LLE-LTP to determine florpyrauxifen-benzyl herbicide in water samples by HPLC-DAD.

Florpyrauxifen-benzyl is a systemic herbicide which acts on weeds of common occurrence in rice cultivation areas using flooded or rainfed systems. The Brazilian Health Regulatory Agency (ANVISA) authorized the commercialization of this pesticide, but did not establish guidelines with an extraction and quantification method of residues of this compound as a form of environmental monitoring. Therefore, the present study aimed to optimize and validate the liquid-liquid extraction with low temperature purification (LLE-LTP) to determine florpyrauxifen-benzyl content in water samples by high performance liquid chromatography with diode array detection (HPLC-DAD). The recovery ranged from 95.84 to 105.4% with a relative standard deviation less than 1.5. LLE-LTP was selective, precise, accurate, linear in the range from 4.00 to 150 µg L-1, and the limit of quantification was 4.00 µg L-1. The stability study of the compound in water revealed its degradation in 25 days and DT50 in approximately 5 days. LLE-LTP coupled to HPLC-DAD presented itself as a simple, easy and efficient method of extracting and analyzing it in water samples.

Factores que afectan el enraizamiento adventicio y brotación en estacas de Hyptis australis (Lamiaceae) / Factors affecting adventitious rooting and sprouting in Hyptis australis (Lamiaceae) cuttings

Resumen Hyptis australis es una especie de la familia Lamiaceae, endémica del Bosque Atlántico, cuyo estado de conservación es crítico y se desconoce aún sus beneficios potenciales para el ecosistema y la sociedad. Con fines de rescate y conservación (ex situ/in situ), se plantea como necesidad, generar un protocolo de propagación vegetativa para facilitar y aumentar la disponibilidad de plantas. Con este objetivo, se estudiaron factores como el tipo de sustrato, tipo de estaca y hormona. Se utilizaron plantas de un año de edad, obtenidas de semillas cosechadas de las plantas ubicadas en la región sur de la provincia de Misiones (Argentina). Estacas apicales y subapicales fueron utilizadas en dos ensayos, en el primero se estudió la factibilidad de inducir raíces adventicias en los sustratos corteza de pino, arena y perlita. En el segundo ensayo, se evaluó la inducción de rizogénesis en estacas tratadas durante 30 minutos con una solución de 100 mg.kg -1 de ácido naftalenacetico (ANA) o ácido indolbutirico (AIB) en corteza de pino. Los mejores resultados se obtuvieron en el sustrato arena y en las estacas terminales. El ANA fue la hormona que generó mayor porcentaje de estacas apicales (80.00±14.14 %) y subapicales (84.00±16.73 %) con raíces. En las estacas subapicales el porcentaje de brotación fue mayor en ambos experimentos. La probabilidad de que una estaca de H. australis desarrolle raíces adventicia depende del tipo de sustrato, pero la adicción de ANA mejora notablemente el porcentaje de enraizamiento.

Abstract Hyptis australis is a species of the Lamiaceae family, endemic to the Atlantic Forest, whose conservation status is critical and its potential benefits for the ecosystem and society are still unknown. For rescue and conservation purposes (ex situ/in situ), the need arises to generate a vegetative propagation protocol to facilitate and increase the availability of plants. With this objective, factors such as the type of substrate, type of stake and hormone were studied. One-year-old plants were used, obtained from seeds harvested from plants located in the southern region of the province of Misiones (Argentina). Apical and subapical cuttings were used in two trials, the first studied the feasibility of inducing adventitious roots in pine bark, sand and perlite substrates. In the second test, the induction of rhizogenesis was evaluated in cuttings treated for 30 minutes with a solution of 100 mg.kg-1 of naphthalenacetic acid (ANA) or indole butyric acid (IBA) in pine bark. The best results were obtained in the sand substrate and in the terminal stakes. ANA was the hormone that generated the highest percentage of apical cuttings (80.00±14.14%) and subapical (84.00±16.73%) with roots. In the subapical cuttings the sprouting percentage was higher in both experiments. The probability that an H. australis cuttings will develop adventitious roots depends on the type of substrate, but the addition of ANA notably improves the rooting percentage.

Sumatran fleabane (Conyza sumatrensis [Retz.] E. Walker) control in soybean with combinations of burndown and preemergence herbicides applied in the off-season

Sumatran fleabane (Conyza sumatrensis [Retz.] E. Walker) can be found in many different agricultural environments and impact different crops, such as soybeans and corn. It is believed that the application of burndown and preemergence herbicides in the off-season are effective in controlling Sumatran fleabane in soybean crops. The objective was to evaluate the effectiveness of burndown and preemergence herbicides in the off-season, with one or two applications, in the control of Sumatran fleabane in soybean cultivation. Five field experiments were conducted in Maripá, state of Paraná (PR), Brazil. The treatments consisted of the application of burndown herbicides in combinations with preemergence ones, with one or two applications. Control of Sumatran fleabane and soybean yield were evaluated. With the set of experiments, it is highlighted that the strategy combining more applications, with different herbicides, burndown and preemergence, is more promising in the control of Sumatran fleabane. When comparing synthetic auxins, dicamba and triclopyr stand out. For sequential application, worse performance was observed for diquat. Combinations between burndown and preemergence herbicides were effective in controlling Sumatran fleabane, for pre sowing application in soybean. With emphasis on managements with sequential applications of saflufenacil with glufosinate or glyphosate. The strategy combining more applications, with different herbicides, burndown and preemergence herbicides, is more promising in the control of Sumatran fleabane.

Unravelling the Molecular Regulation Mechanisms of Slow Ripening Trait in Prunus persica.

Fruit development is a complex process that involves the interplay of cell division, expansion, and differentiation. As a model to study fruit development, nectarines incapable of ripening were described as slow ripening. Slow ripening fruits remained firm and exhibited no rise in CO2 or ethylene production rates for one month or more at 20 °C. Different studies suggest that this trait is controlled by a single gene (NAC072). Transcriptome analysis between normal and slow ripening fruits showed a total of 157, 269, 976, and 5.224 differentially expressed genes in each fruit developmental stage analyzed (T1, T2, T3, and T7, respectively), and no expression of NAC072 was found in the slow ripening individuals. Using this transcriptomic information, we identified a correlation of NAC072 with auxin-related genes and two genes associated with terpene biosynthesis. On the other hand, significant differences were observed in hormonal biosynthetic pathways during fruit development between the normal and slow ripening individuals (gibberellin, ethylene, jasmonic acid and abscisic acid). These results suggest that the absence of NAC072 by the direct or indirect expression control of auxins or terpene-related genes prevents normal peach fruit development.

Genome-Wide Analysis, Modeling, and Identification of Amino Acid Binding Motifs Suggest the Involvement of GH3 Genes during Somatic Embryogenesis of Coffea canephora.

Auxin plays a central role in growth and plant development. To maintain auxin homeostasis, biological processes such as biosynthesis, transport, degradation, and reversible conjugation are essential. The Gretchen Hagen 3 (GH3) family genes codify for the enzymes that esterify indole-3-acetic acid (IAA) to various amino acids, which is a key process in the induction of somatic embryogenesis (SE). The GH3 family is one of the principal families of early response to auxin genes, exhibiting IAA-amido synthetase activity to maintain optimal levels of free auxin in the cell. In this study, we carried out a systematic identification of the GH3 gene family in the genome of Coffea canephora, determining a total of 18 CcGH3 genes. Analysis of the genetic structures and phylogenetic relationships of CcGH3 genes with GH3 genes from other plant species revealed that they could be clustered in two major categories with groups 1 and 2 of the GH3 family of Arabidopsis. We analyzed the transcriptome expression profiles of the 18 CcGH3 genes using RNA-Seq analysis-based data and qRT-PCR during the different points of somatic embryogenesis induction. Furthermore, the endogenous quantification of free and conjugated indole-3-acetic acid (IAA) suggests that the various members of the CcGH3 genes play a crucial role during the embryogenic process of C. canephora. Three-dimensional modeling of the selected CcGH3 proteins showed that they consist of two domains: an extensive N-terminal domain and a smaller C-terminal domain. All proteins analyzed in the present study shared a unique conserved structural topology. Additionally, we identified conserved regions that could function to bind nucleotides and specific amino acids for the conjugation of IAA during SE in C. canephora. These results provide a better understanding of the C. canephora GH3 gene family for further exploration and possible genetic manipulation.

What Do We Know About the Publications Related with Azospirillum? A Metadata Analysis.

Azospirillum is one of the most successful plant growth-promoting bacteria (PGPB) genera and it is considered a study model for plant-bacteria interactions. Because of that, a wide broad of topics has been boarded and discussed in a significant number of publications in the last four decades. Using the Scopus® database, we conducted a bibliographic search in order to analyze the number and type of publications, the authors responsible of these contributions, and the origin of the researchers, as well as the keywords and journals selected by the authors, among other related characteristics, with the aim to understand some less addressed details about the work done with Azospirillum worldwide since its discovery in 1925. Despite that the largest numbers of publications about this bacterium were obtained between the 1970 and 1980s, there is still a linear increase tendency in the number of published works. Understanding the mechanisms involved in the ability of these bacteria to promote growth in a wide broad of plant species under both laboratory and field conditions has been a preferential target for these published articles. This tendency could be considered a cause or consequence of the current increase in the number of commercial products formulated with Azospirillum around the world and a catalyzer for the increase of published articles along time.

Purple nutsedge (Cyperus rotundusL)extract as carrot growth and production inducer / Extrato de tiririca (Cyperus rotundusL)como indutor de crescimento e produção de cenoura

There is evidence that the purple nutsedge(Cyperus rotundusL.) aqueous extract can induce the plants rooting due to the high auxin concentrations. This study aimed to evaluate the effect of application seasons and concentrations of purple nutsedgeaqueous extract application on the growth and production of carrot, cultivar Brasília. The experimentaldesign was in randomized blocks, in a 2 x 5 factorial scheme in two seasons of the extract application (25 and 50 days after sowing) and five concentrations of (0%, 10%, 20%, 30% and 40%) with four replicates. Harvesting was carriedout at 90 days after sowing, being evaluated the following morphological parameters: root diameter (cm); root fresh mass (g plant-1); plant height (cm); aerial part fresh mass (g plant-1); root dry mass (g plant-1); aerial part dry mass (g plant-1); plantdry mass (g plant-1); ratio between root dry mass and aerial part dry mass; root length (cm); commercial productivity (t ha-1); defective root mass (t ha-1); totalproductivity (t ha-1); commercial yield (roots kg-1); and root classification by length. The extract application at 50thday was more efficient for the root diameter (3.37 cm); fresh root mass(120.7 g plant-1); root length (15.4 cm); commercial productivity (68.2 t ha-1); total productivity (73.6 t ha-1); and commercial roots (8.8 roots kg-1). Root classification by length showed a higher percentage in the 14 cm classification range. The parameters did not present significant differences in both seasons, at 25th and 50thdays, respectively, for root dry mass (12.0 and 12.8 g plant-1), ratio between dry mass of roots and aerial part (1.66 and 1.57), and defective root mass (1.3 and 1.5 t ha-1).(AU)

Há evidências de que oextrato aquoso de tiririca (Cyperus rotundusL.)possa induzir o enraizamento de plantas, por apresentar elevadas concentrações de auxinas. O objetivo deste trabalho foi avaliar o efeito deépocas de aplicação econcentrações de extrato aquoso de tiririca no desenvolvimento e produção da cenoura, cultivar Brasília. O delineamento experimental foi em blocos casualizados, em esquema fatorial 2 x 5, sendo duas épocas de aplicação do extrato (25 e 50 dias após semeadura) e cinco concentrações deextrato de tiririca (0%, 10%, 20%, 30% e 40% v/v), com 4 repetições. A colheita foi realizadaaos 90 dias após a semeadura, sendo avaliados os seguintes parâmetros morfológicos: diâmetro de raízes (cm); altura de plantas (cm); massa fresca de raízes e daparte aérea (g planta-1); massa seca de raízes e da parte aérea (g planta-1); massa seca total (g planta-1); razão das massasseca de raízes e parte aérea; comprimento de raízes (cm); produtividade comercial (t ha-1);massa de raízes com defeito (t ha-1);produtividade total (t ha-1);rendimento comercial (raízes kg-1); e classificação das raízes por comprimento.A aplicação do extrato aos 50 dias mostrou-se mais eficiente aodiâmetro de raiz (3,37 cm),massa fresca de raízes (120,7 g planta-1), comprimento de raízes (15,4cm), produtividade comercial (68,2 t ha-1), produtividade total (73,6 t ha-1) e raízes comerciais (8,8 raízes kg-1). A classificação das raízes apresentou maior porcentagem na classe de 14 cm. Os parâmetros massa seca de raiz (12,0 e 12,8g planta-1), razão de massa seca de raízes e parte aérea (1,66 e 1,57) emassa de raízes com defeito(1,3 e 1,5 t ha-1), aos 25 e 50 dias,respectivamente,foram semelhantes em ambas as épocas.(AU)

Purple nutsedge (Cyperus rotundusL)extract as carrot growth and production inducer / Extrato de tiririca (Cyperus rotundusL)como indutor de crescimento e produção de cenoura

There is evidence that the purple nutsedge(Cyperus rotundusL.) aqueous extract can induce the plants rooting due to the high auxin concentrations. This study aimed to evaluate the effect of application seasons and concentrations of purple nutsedgeaqueous extract application on the growth and production of carrot, cultivar Brasília. The experimentaldesign was in randomized blocks, in a 2 x 5 factorial scheme in two seasons of the extract application (25 and 50 days after sowing) and five concentrations of (0%, 10%, 20%, 30% and 40%) with four replicates. Harvesting was carriedout at 90 days after sowing, being evaluated the following morphological parameters: root diameter (cm); root fresh mass (g plant-1); plant height (cm); aerial part fresh mass (g plant-1); root dry mass (g plant-1); aerial part dry mass (g plant-1); plantdry mass (g plant-1); ratio between root dry mass and aerial part dry mass; root length (cm); commercial productivity (t ha-1); defective root mass (t ha-1); totalproductivity (t ha-1); commercial yield (roots kg-1); and root classification by length. The extract application at 50thday was more efficient for the root diameter (3.37 cm); fresh root mass(120.7 g plant-1); root length (15.4 cm); commercial productivity (68.2 t ha-1); total productivity (73.6 t ha-1); and commercial roots (8.8 roots kg-1). Root classification by length showed a higher percentage in the 14 cm classification range. The parameters did not present significant differences in both seasons, at 25th and 50thdays, respectively, for root dry mass (12.0 and 12.8 g plant-1), ratio between dry mass of roots and aerial part (1.66 and 1.57), and defective root mass (1.3 and 1.5 t ha-1).

Há evidências de que oextrato aquoso de tiririca (Cyperus rotundusL.)possa induzir o enraizamento de plantas, por apresentar elevadas concentrações de auxinas. O objetivo deste trabalho foi avaliar o efeito deépocas de aplicação econcentrações de extrato aquoso de tiririca no desenvolvimento e produção da cenoura, cultivar Brasília. O delineamento experimental foi em blocos casualizados, em esquema fatorial 2 x 5, sendo duas épocas de aplicação do extrato (25 e 50 dias após semeadura) e cinco concentrações deextrato de tiririca (0%, 10%, 20%, 30% e 40% v/v), com 4 repetições. A colheita foi realizadaaos 90 dias após a semeadura, sendo avaliados os seguintes parâmetros morfológicos: diâmetro de raízes (cm); altura de plantas (cm); massa fresca de raízes e daparte aérea (g planta-1); massa seca de raízes e da parte aérea (g planta-1); massa seca total (g planta-1); razão das massasseca de raízes e parte aérea; comprimento de raízes (cm); produtividade comercial (t ha-1);massa de raízes com defeito (t ha-1);produtividade total (t ha-1);rendimento comercial (raízes kg-1); e classificação das raízes por comprimento.A aplicação do extrato aos 50 dias mostrou-se mais eficiente aodiâmetro de raiz (3,37 cm),massa fresca de raízes (120,7 g planta-1), comprimento de raízes (15,4cm), produtividade comercial (68,2 t ha-1), produtividade total (73,6 t ha-1) e raízes comerciais (8,8 raízes kg-1). A classificação das raízes apresentou maior porcentagem na classe de 14 cm. Os parâmetros massa seca de raiz (12,0 e 12,8g planta-1), razão de massa seca de raízes e parte aérea (1,66 e 1,57) emassa de raízes com defeito(1,3 e 1,5 t ha-1), aos 25 e 50 dias,respectivamente,foram semelhantes em ambas as épocas.

Hemicelluloses and associated compounds determine gall functional traits.

The intriguing questions concerning gall development refer to the processes of the remodelling of the host plant organ. Such processes involve the restructuring of cell walls and can be influenced by phenolics, indole-3-acetic acid (IAA) and reactive oxygen species (ROS). Alterations in cell walls demand the interference in the coupling of cellulose fibrils and hemicelluloses (xyloglucans) at specific stages of gall development. In addition to cell wall remodelling, hemicelluloses, such as the, xyloglucans and heteromannans can act as reserve carbohydrates, while xylans provide rigidity to the secondary cell walls. Developmental traits of the lenticular, fusiform and globoid galls on Inga ingoides (Fabaceae) were analysed using anatomical, cytometric, histochemical and immunocytochemical tools. Phenolics, IAA and ROS accumulated in similar gall tissue compartments, and may have influenced the restructuring of hemicelluloses and pectins. Contrary to expectations, cell wall flexibility regarding the dynamics of xyloglucans and cellulose fibrils does not relate to a temporal scale. The detection of xyloglucans in nutritive cell walls relate to carbohydrate nutritional resources to the galling insect, while xylans were associated to the lignified cell walls. Heteromanans were not detected, either in non-galled or galled tissues. The patterns of cell expansion during gall development relied on the relationship among phenolics, ROS and IAA with the hemicelluloses (xyloglucans and xylans) and cellulose fibrils. Although cell wall dynamics is specific to each gall morphotype in I. ingoides, the xyloglucans function as carbohydrate reserve to the gall inducers, which constitutes a functional trait common to the three morphotypes.

Micropropagation of Stevia rebaudiana plants / Micropropagação de plantas de Stevia rebaudiana

The aim of the study was to develop optimum composition of plant growth regulators in media for the propagation and rooting of shoots of stevia (Stevia rebaudiana Bertoni) in in vitro cultures. Single-node shoot fragments obtained from plants propagated on MS medium were placed onto media supplemented with: BAP, 2iP and KIN at concentrations: 0.5, 1, 2 and 5 mg∙dm-3, whereas at the rooting stage with addition of: IAA, IBA and NAA at concentrations 1, 2, 4 and 8 mg∙dm-3. The highest number of shoots and leaves was reported for plants propagated on MS medium enriched with 0.5 mg∙dm-3 BAP. The greatest number of the longest roots was developed by stevia on the MS medium enriched with 1 mg∙dm-3 IAA.(AU)

O objetivo do estudo foi desenvolver uma composição ótima de reguladores de crescimento em meios para a propagação e enraizamento de brotos de estévia (Stevia rebaudiana Bertoni) em culturas in vitro. Fragmentos de parte aérea obtidos de plantas propagadas em meio MS foram colocados em meio suplementado com: BAP, 2iP e KIN nas concentrações: 0.5, 1, 2 e 5 mg∙dm-3, enquanto no estádio de enraizamento com adição de: IAA, IBA e ANA nas concentrações 1, 2, 4 e 8 mg∙dm-3.O maior número de brotações e folhas foi encontrado para plantas propagadas em meio MS enriquecido com 0.5 mg∙dm-3 de BAP. O maior número de raízes mais longas foi desenvolvido por estévia no meio MS enriquecido com 1 mg∙dm-3 de IAA.(AU)

Micropropagation of Stevia rebaudiana plants / Micropropagação de plantas de Stevia rebaudiana

ABSTRACT: The aim of the study was to develop optimum composition of plant growth regulators in media for the propagation and rooting of shoots of stevia (Stevia rebaudiana Bertoni) in in vitro cultures. Single-node shoot fragments obtained from plants propagated on MS medium were placed onto media supplemented with: BAP, 2iP and KIN at concentrations: 0.5, 1, 2 and 5 mg∙dm-3, whereas at the rooting stage with addition of: IAA, IBA and NAA at concentrations 1, 2, 4 and 8 mg∙dm-3. The highest number of shoots and leaves was reported for plants propagated on MS medium enriched with 0.5 mg∙dm-3 BAP. The greatest number of the longest roots was developed by stevia on the MS medium enriched with 1 mg∙dm-3 IAA.

RESUMO: O objetivo do estudo foi desenvolver uma composição ótima de reguladores de crescimento em meios para a propagação e enraizamento de brotos de estévia (Stevia rebaudiana Bertoni) em culturas in vitro. Fragmentos de parte aérea obtidos de plantas propagadas em meio MS foram colocados em meio suplementado com: BAP, 2iP e KIN nas concentrações: 0.5, 1, 2 e 5 mg∙dm-3, enquanto no estádio de enraizamento com adição de: IAA, IBA e ANA nas concentrações 1, 2, 4 e 8 mg∙dm-3.O maior número de brotações e folhas foi encontrado para plantas propagadas em meio MS enriquecido com 0.5 mg∙dm-3 de BAP. O maior número de raízes mais longas foi desenvolvido por estévia no meio MS enriquecido com 1 mg∙dm-3 de IAA.