Roychoudhury Aryadeep, Basu Supratim, Sengupta Dibyendu N
Department of Botany, Bose Institute, 93/1, Acharya Prafulla Chandra Road, Kolkata 700 009, India.
Indian J Exp Biol. 2009 Oct;47(10):827-33.
As an integral part of stress signal transduction, the phytohormone abscisic acid (ABA) regulates important cellular reactions, including up-regulation of stress-associated genes, the products of which are involved directly or indirectly in plant protection. Being accompanied by an increased endogenous ABA level, the matured seeds, embryo and aleurone tissues of cereals accumulate several genes and proteins, associated with desiccation. The present study was aimed at investigating how the contrasting rice genotypes, varying in their salt-stress sensitivity, differ with respect to the expression pattern of two abiotic stress-inducible genes, Rab16A and SamDC, and corresponding proteins, in the seeds, at the background level (dry or water-imbibed state) and ABA-imbibed conditions, which could be related to the varietal differences in tolerance. The rice genotypes selected were M-1-48 (salt-sensitive), Nonabokra (salt-tolerant) and Gobindobhog (aromatic). An extremely low abundance of Rab16A or practically undetectable SamDC transcripts were observed in M-1-48 and Gobindobhog seeds under control conditions, induced only after exogenous ABA treatment, whereas they were expressed at a much higher level even in dry and water-imbibed seeds of Nonabokra, and lesser induced by ABA. The RAB16A (=dehydrin) and SAMDC protein expression in the three varieties were also identical to the gene expression patterns. Thus, the expression was stress-inducible in M-1-48 and Gobindobhog, while constitutive in Nonabokra. Our study reflected the similarity of the molecular responses to exogenous ABA of the seeds of the aromatic rice Gobindobhog to that of the salt-sensitive M-1-48, in exhibiting lower expression of stress-tolerant proteins only after stress. This work also proved that variation in gene/protein expression in seeds could be highly correlated with the variation in the tolerance mechanism of rice varieties.
作为应激信号转导的一个组成部分，植物激素脱落酸（ABA）调节重要的细胞反应，包括上调与应激相关的基因，这些基因的产物直接或间接参与植物保护。伴随着内源性ABA水平的升高，谷类作物的成熟种子、胚和糊粉层组织积累了几种与脱水相关的基因和蛋白质。本研究旨在调查盐胁迫敏感性不同的水稻基因型在种子中，在基础水平（干燥或吸水状态）和ABA吸水条件下，两个非生物胁迫诱导基因Rab16A和SamDC及其相应蛋白质的表达模式有何差异，这可能与品种间的耐受性差异有关。所选的水稻基因型为M-1-48（盐敏感型）、Nonabokra（耐盐型）和Gobindobhog（香型）。在对照条件下，M-1-48和Gobindobhog种子中观察到Rab16A的丰度极低或SamDC转录本几乎检测不到，仅在外源ABA处理后诱导表达，而即使在Nonabokra的干燥和吸水种子中，它们的表达水平也高得多，且ABA诱导程度较小。三个品种中RAB16A（=脱水素）和SAMDC蛋白的表达也与基因表达模式一致。因此，M-1-48和Gobindobhog中的表达是应激诱导型的，而在Nonabokra中是组成型的。我们的研究反映了香型水稻Gobindobhog种子对外源ABA的分子反应与盐敏感型M-1-48相似，即仅在应激后才表现出较低的耐逆蛋白表达。这项工作还证明了种子中基因/蛋白质表达的变化可能与水稻品种耐受机制的变化高度相关。
