Abstract
Drought is one of the most critical factors limiting legume crop productivity. Understanding the molecular mechanisms of drought tolerance in the common bean is required to improve the yields of this important crop under adverse conditions. In this work, RNA-seq analysis was performed to compare the transcriptome profiles of drought-stressed and well-irrigated plants of a previously characterized drought-tolerant common bean landrace. The analysis revealed responses related with the abscisic acid signaling, including downregulation of a phosphatase 2C (PP2C) and an abscisic acid-8′ hydroxylase, and upregulation of several key transcription factors and genes involved in cell wall remodeling, synthesis of osmoprotectants, protection of photosynthetic apparatus, and downregulation of genes involved in cell expansion. The results also highlighted a significant proportion of differentially expressed genes related to phosphate starvation response. In addition, the moderate detrimental effects of drought in the biomass of these tolerant plants were abolished by the addition of phosphate, thus indicating that, besides the ABA-mediated response, acquisition of phosphate could be crucial for the drought tolerance of this common bean genotype. These results provided information about the mechanisms involved in drought response of common bean response that could be useful for enhancing the drought tolerance of this important crop legume.
Highlights
Common bean (Phaseolus vulgaris) is the most important legume for human consumption worldwide
To elucidate the molecular strategies displayed by common bean landrace PHA-683 to tolerate drought conditions, the RNA-seq approach was chosen to compare the genome-wide changes in transcript levels in response to water deficit
The whole plant dry weight of drought-stressed high P plants was significantly higher than in the normal P stressed ones (Figure 7D). These results suggested that drought strongly affected P nutrition and that, at least in part, the moderate negative drought effects on plant biomass of this tolerant common bean landrace could be alleviated when higher P concentration is supplied. Functional genomic tools, such as whole-genome sequencing of transcripts, are currently one of the most useful technologies to clarify the molecular mechanisms of complex traits, such as drought tolerance and, to obtain more efficient crops in conditions of abiotic stresses
Summary
Common bean (Phaseolus vulgaris) is the most important legume for human consumption worldwide It is grown throughout the world, especially in developing countries, with a large economic and social impact [1,2,3]. Besides limiting fixed nitrogen supply, drought affects the absorption of mineral nutrients and translocation of assimilates, resulting in a drastic reduction in yield [2,10,11]. Due to their high dissemination and diversity, common beans exhibit enormous genotypic variability in their drought tolerance [2,8,12]. Drought tolerance has been evaluated in many bean germplasm collections, revealing the complexity of the trait, which has additive and quantitative effects, and very significant interaction with the environment [13,14], limiting the obtention of highly drought-tolerant cultivars
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