Expressão gênica induzida por estresses abióticos em nódulos de feijão-caupi

Abstract

Resumo -O objetivo deste trabalho foi avaliar o efeito isolado ou simultâneo dos estresses hídrico e térmico na expressão gênica em nódulos de feijão-caupi. A bactéria Bradyrhizobium japonicum (estirpe BR 3267) foi inoculada em sementes de feijão-caupi da cultivar IPA 206 e, 35 dias após a germinação, as plantas foram submetidas a diferentes regimes de disponibilidade hídrica e a estresse térmico, em casa de vegetação. Para a identificação dos genes diferencialmente expressos, foi utilizada a técnica de cDNA-AFLP, tendo-se isolado 67 fragmentos derivados de transcritos (FDTs) diferencialmente expressos. Após o sequenciamento dos FDTs e das análises de similaridade, com uso do programa Blastx, foram identificados 14 genes diferencialmente expressos envolvidos em diferentes processos metabólicos. O padrão de expressão de seis genes sob estresse abiótico foi confirmado por RT-qPCR, e observou-se indução de genes pertencentes a diferentes categorias funcionais, como biossíntese de ácido abscísico, sinalização celular, transportador de prolina e biossíntese de lipídeos de membranas. A expressão desses genes indica sua participação em processos relacionados à proteção dos nódulos ao estresse abiótico.Termos para indexação: Vigna unguiculata, cDNA-AFLP, fixação biológica de nitrogênio, genômica funcional. Gene expression induced by abiotic stress in cowpea nodulesAbstract -The objective of this work was to evaluate the isolated or concomitant effect of drought and heat stresses on the gene expression of cowpea nodules. The bacterium Bradyrhizobium japonicum (strain BR 3267) was inoculated in cowpea seeds from the cultivar IPA 206 and, 35 days after germination, the plants were subjected to different water availability regimes and to heat stress under greenhouse conditions. To identify differentially expressed genes, the cDNA-AFLP technique was used, and 67 differentially expressed transcript-derived fragments (TDFs) were isolated. After TDFs sequencing and similarity analyses, using the Blastx program, 14 differentially expressed genes were identified, which are involved in different metabolic processes. The expression pattern of six genes under abiotic stress conditions was confirmed by RT-qPCR, and the induction of different functional gene categories, such as abscisic acid biosynthesis, cell signaling, proline transporter, and lipid membrane biosynthesis, was observed. The expression of these genes indicates their participation in processes related to nodule protection under abiotic stresses.Index terms: Vigna unguiculata, cDNA-AFLP, biological nitrogen fixation, functional genomics. IntroduçãoEm condições tropicais, a produtividade agrícola pode ser negativamente afetada por uma série de estresses bióticos e abióticos que alteram o crescimento e o desenvolvimento vegetal. Nesse contexto, destacamse a deficiência de nutrientes, como nitrogênio e fósforo, bem como os estresses decorrentes da baixa disponibilidade hídrica e das altas temperaturas.A fixação biológica de nitrogênio (FBN) é um processo complexo que pode ...

Evaluation of Reference Genes for RT‐qPCR Normalization in Cowpea under Drought Stress during Biological Nitrogen Fixation

“…We have used the best and the worst reference genes determined by NormFinder algorithm for global and organ-specific analyses (Table 3). In agreement with previous results, VusHsp17.7 was significantly induced in root nodules and leaves in response to drought stress (Da Silva et al, 2012). Moreover, its expression profile was very similar in both organs; however, the VusHsp17.7 transcripts levels in nodules were extremely high (Fig.…”

Cowpea: a legume crop for a challenging environment

“…Two other well‐recognized stress‐related genes, GST (glutathione‐S‐transferase) and PR‐1 (pathogenesis‐related‐protein‐1), were identified in cowpea by suppression subtractive hybridization (SSH) using drought‐tolerant and susceptible lines . Silva et al . followed the effect of drought and heat stresses on cowpea nodules by evaluating the differential gene expression, using a cDNA‐AFLP approach, and identified 14 differentially expressed nodule stress responsive genes.…”

“…followed the effect of drought and heat stresses on cowpea nodules by evaluating the differential gene expression, using a cDNA‐AFLP approach, and identified 14 differentially expressed nodule stress responsive genes. These genes are involved in different metabolic processes, five ( VuNSR4 , VuNSR10 , VuNSR44 , VuNSR47 and VuNSR49 ) of which were related with the nodule protection under abiotic stress conditions as revealed by their expression levels …”

“…111 Two other well-recognized stress-related genes, GST (glutathione-S-transferase) and PR-1 (pathogenesis-related-protein-1), were identified in cowpea by suppression subtractive hybridization (SSH) using drought-tolerant and susceptible lines. 148 Silva et al 149 followed the effect of drought and heat stresses on cowpea nodules by evaluating the differential gene expression, using a cDNA-AFLP approach, and identified 14 differentially expressed nodule stress responsive genes. These genes are involved in different metabolic processes, five (VuNSR4, VuNSR10, VuNSR44, VuNSR47 and VuNSR49) of which were related with the nodule protection under abiotic stress conditions as revealed by their expression levels.…”

Gene Expression of the Expansin Family in Silk Cotton under Water Stress

“…In tropical conditions, agricultural productivity may be negatively affected by a series of biotic and abiotic stresses that alter plant growth and development (Silva et al, 2012). In this context, there are mainly prolonged droughts, responsible for the great variability of agricultural production.…”