Project description:Common bean (Phaseolus vulgaris L.) is a relevant crop cultivated over the world, largely in water insufficiency vulnerable areas. Since drought is the main environmental factor restraining worldwide crop production, efforts have been invested to amend drought tolerance in commercial common bean varieties. However, scarce molecular data are available for those cultivars of P. vulgaris with drought tolerance attributes. As a first approach, Pinto Saltillo (PS), Azufrado Higuera (AH), and Negro Jamapa Plus (NP) were assessed phenotypically and physiologically to determine the outcome in response to drought on these common bean cultivars. Based on this, a Next-generation sequencing approach was applied to PS, which was the most drought-tolerant cultivar to determine the molecular changes at the transcriptional level. The RNA-Seq analysis revealed that numerous PS genes are dynamically modulated by drought. In brief, 1005 differentially expressed genes (DEGs) were identified, from which 645 genes were up-regulated by drought stress, whereas 360 genes were down-regulated. Further analysis showed that the enriched categories of the up-regulated genes in response to drought fit to processes related to carbohydrate metabolism (polysaccharide metabolic processes), particularly genes encoding proteins located within the cell periphery (cell wall dynamics). In the case of down-regulated genes, heat shock-responsive genes, mainly associated with protein folding, chloroplast, and oxidation-reduction processes were identified. Our findings suggest that secondary cell wall (SCW) properties contribute to P. vulgaris L. drought tolerance through alleviation or mitigation of drought-induced osmotic disturbances, making cultivars more adaptable to such stress. Altogether, the knowledge derived from this study is significant for a forthcoming understanding of the molecular mechanisms involved in drought tolerance on common bean, especially for drought-tolerant cultivars such as PS.

Project description:Drought stress response involves vigorous reprogramming of transcriptome while the mechanism modulating this process remains elusive. The role of 3D-genome in the regulation of rice development has recently been unveiled in rice, which exhibited characteristics distinct from that in mammals and other plants. However, the relationship between spatial chromosome organization and drought responsive gene reprogramming is still poorly understood. In this study, we identified H3K9ac as an efficient histone mark that response dynamically to drought stress in rice and re-constructed high-resolution 3D genome contact maps based on these sites under the normal, drought, and recovery conditions. We discovered significant decondensation of chromatin contacts with over 10000 chromatin loops lost upon drought stress treatment while the recovery of 3D genome was limited after 4-day’s re-watering. We identified dominate promoter-promoter interacting (PPI) loops under each condition and identified their significant correlations to altered gene expressions in response to the corresponding condition. Based on the relative contact intensities of the PPI connections, we characterized super-promoter regions that integrate closer connections of genes with more vigorous inductions to condition shifts. Especially, about 75% of the drought stress-dominate PPI loops were associated to the binding by a well-defined drought stress-responsive transcription factor, OsbZIP23. The mutation of OsbZIP23 led to the diffuse of over 80% DS-dominate PPI loops and impaired the expression of the connected genes. As a case study, we showed how OsbZIP23 binding to a super-promoter region can integrate the PPI loop formation and transcriptional activation of four function-vital dehydrin genes upon drought stress. Our results shed light on the mechanisms of 3D genome dynamic in response to water supply variations in rice and highlight the role of OsbZIP23 in the regulation of chromatin loop formation under drought stress.

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FAIRE (Formaldehyde-Assisted Isolation of Regulatory Elements) analysis of chromatin accessibility in kidney bean under drought stress

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