Transcriptional Analysis of Drought-Induced Genes in the Roots of a Tolerant Genotype of the Common Bean (Phaseolus vulgaris L.)

Abstract

In Brazil, common bean (Phaseolus vulgaris L.) productivity is severely affected by drought stress due to low technology cultivation systems. Our purpose was to identify differentially expressed genes in roots of a genotype tolerant to water deficit (BAT 477) when submitted to an interruption of irrigation during its development. A SSH library was constructed taking as “driver” the genotype Carioca 80SH (susceptible to drought). After clustering and data mining, 1572 valid reads were obtained, resulting in 1120 ESTs (expressed sequence tags). We found sequences for transcription factors, carbohydrates metabolism, proline-rich proteins, aquaporins, chaperones and ubiquitins, all of them organized according to their biological processes. Our suppressive subtractive hybridization (SSH) library was validated through RT-qPCR experiment by assessing the expression patterns of 10 selected genes in both genotypes under stressed and control conditions. Finally, the expression patterns of 31 ESTs, putatively related to drought responses, were analyzed in a time-course experiment. Our results confirmed that such genes are more expressed in the tolerant genotype during stress; however, they are not exclusive, since different levels of these transcripts were also detected in the susceptible genotype. In addition, we observed a fluctuation in gene regulation over time for both the genotypes, which seem to adopt and adapt different strategies in order to develop tolerance against this stress.

Genome-wide identification and characterization of aquaporin gene family in common bean (Phaseolus vulgaris L.)

“…Transcriptome analysis in common bean under drought stress using EST approaches showed contrasting expression patterns between tolerant and susceptible genotypes (Montalvo-Hernández et al 2008;Recchia et al 2013). Susceptible genotypes showed a marked down-regulation of aquaporins expression in response to drought, while resistant showed a stable or higher expression of these genes.…”

“…Despite the possible importance of aquaporin in regulating drought stress response in common bean (Aroca et al 2006;Montalvo-Hernández et al 2008;Recchia et al 2013), none of the droughtQTLs identified by Mukeshimana et al (2014) are located near aquaporin loci. The response variables analyzed in the above-mentioned study were mainly related to flowering time, maturity, and seed productivity, suggesting that aquaporins could have only a marginal role in these developmental processes in common bean.…”

“…Several experiments identified aquaporins as involved in response to drought stress in common beans varieties, and marked differences in gene expression were observed in drought-resistant versus susceptible genotypes (Aroca et al 2006;Montalvo-Hernández et al 2008;Recchia et al 2013). In particular, a tolerant genotype showed increased expression of a tonoplast aquaporin in drought-stressed roots, with re-localization of its mRNA in phloem tissues (Montalvo-Hernández et al 2008).…”

Expression of drought tolerance genes in tropical upland rice cultivars (Oryza sativa)

“…Understanding abiotic stress responses in plants is difficult due to the complexity, interrelationships, and variability of mechanisms and molecules involved. However, it is important to understand the mechanisms by which tolerant cultivars respond to stress in order to select genes that may be useful in rice breeding programs (Recchia et al, 2013).…”

Functional Genomics of Biotic and Abiotic Stresses in Phaseolus vulgaris

“…The SSH method [76] consists on the hybridization of one cDNA population (tester -sample whose genetic profile is of interest, e.g., drought-tolerant genotype), with an excess of cDNA from a control population (driver -usually drought-susceptible genotype or well-watered control), followed by the separation of the nonhybridized molecules (target genes -the ones of interest) from the hybridized ones (what is common for both samples). In this session, we are aiming to present some of the results obtained by our group during the construction of a SSH library contrasting populations of cDNAs extracted from root tissues of two common bean genotypes, BAT 477 (tester -drought-tolerant) and Carioca 80SH (driver -drought-susceptible), both submitted to a 192 hours of water-deficit regime at the R5 developmental stage [77].…”