Consejo Nacional de Ciencia y Tecnología - Centro de Investigación en Biotecnología Aplicada, Instituto Politécnico Nacional (CIBA-IPN), Ex-Hacienda San Juan Molino, Carretera Estatal Tecuexcomac- Tepetitla de Lardizábal Km 1.5, 90700, Tlaxcala, Mexico.
Laboratorio de Genómica Funcional y Biotecnología de Plantas, Centro de Investigación en Biotecnología Aplicada, Instituto Politécnico Nacional (CIBA-IPN), Ex-Hacienda San Juan Molino, Carretera Estatal Tecuexcomac- Tepetitla de Lardizábal Km 1.5, 90700, Tlaxcala, Mexico.
BMC Plant Biol. 2020 Nov 17;20(1):525. doi: 10.1186/s12870-020-02664-1.
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.
普通菜豆（Phaseolus vulgaris L.）是一种在世界各地广泛种植的重要作物，主要种植在水资源不足的脆弱地区。由于干旱是全球作物生产的主要环境因素，因此人们一直在努力改善商业普通菜豆品种的耐旱性。然而，对于具有耐旱性特征的 P. vulgaris 栽培品种，可用的分子数据却很少。
作为第一步，对 Pinto Saltillo（PS）、Azufrado Higuera（AH）和 Negro Jamapa Plus（NP）进行了表型和生理评估，以确定这些普通菜豆品种在干旱条件下的反应结果。基于此，对 PS 进行了下一代测序方法的应用，PS 是最耐旱的品种，以确定转录水平上的分子变化。RNA-Seq 分析表明，大量 PS 基因受干旱的动态调节。简而言之，鉴定出 1005 个差异表达基因（DEGs），其中 645 个基因受干旱胁迫上调，而 360 个基因下调。进一步分析表明，响应干旱上调基因的富集类别与碳水化合物代谢（多糖代谢过程）相关的过程相吻合，特别是编码位于细胞外周（细胞壁动态）的蛋白质的基因。在下调基因的情况下，鉴定出与热休克反应相关的基因，主要与蛋白质折叠、叶绿体和氧化还原过程相关。
我们的研究结果表明，次生细胞壁（SCW）特性通过缓解或减轻干旱引起的渗透胁迫，有助于 P. vulgaris L. 的耐旱性，使品种更能适应这种胁迫。总之，本研究的结果对于深入了解普通菜豆耐旱性的分子机制具有重要意义，特别是对于 PS 等耐旱品种。
