Lekshmy V S, Vijayaraghavareddy Preethi, Nagashree A N, Ramu Vemanna S, Ramegowda Venkategowda, Makarla Udayakumar, Sreeman Sheshshayee
Department of Crop Physiology, University of Agricultural Sciences, Bengaluru, India.
Department of Plant Sciences, Centre for Crop Systems Analysis, Wageningen University & Research, Wageningen, Netherlands.
Front Plant Sci. 2021 Feb 18;11:632919. doi: 10.3389/fpls.2020.632919. eCollection 2020.
Plants have evolved several adaptive mechanisms to cope with water-limited conditions. While most of them are through constitutive traits, certain "acquired tolerance" traits also provide significant improvement in drought adaptation. Most abiotic stresses, especially drought, show a gradual progression of stress and hence provide an opportunity to upregulate specific protective mechanisms collectively referred to as "acquired tolerance" traits. Here, we demonstrate a significant genetic variability in acquired tolerance traits among rice germplasm accessions after standardizing a novel gradual stress progress protocol. Two contrasting genotypes, BPT 5204 (drought susceptible) and AC 39000 (tolerant), were used to standardize methodology for capturing acquired tolerance traits at seedling phase. Seedlings exposed to gradual progression of stress showed higher recovery with low free radical accumulation in both the genotypes compared to rapid stress. Further, the gradual stress progression protocol was used to examine the role of acquired tolerance at flowering phase using a set of 17 diverse rice genotypes. Significant diversity in free radical production and scavenging was observed among these genotypes. Association of these parameters with yield attributes showed that genotypes that managed free radical levels in cells were able to maintain high spikelet fertility and hence yield under stress. This study, besides emphasizing the importance of acquired tolerance, explains a high throughput phenotyping approach that significantly overcomes methodological constraints in assessing genetic variability in this important drought adaptive mechanism.
植物已经进化出多种适应机制来应对水分有限的条件。虽然其中大多数是通过组成型性状实现的，但某些“获得性耐受”性状也能显著提高对干旱的适应性。大多数非生物胁迫，尤其是干旱，呈现出胁迫的逐渐发展过程，因此提供了一个上调特定保护机制的机会，这些机制统称为“获得性耐受”性状。在此，我们在标准化了一种新的逐渐胁迫进展方案后，证明了水稻种质资源在获得性耐受性状方面存在显著的遗传变异。使用两个对比基因型，BPT 5204（干旱敏感型）和AC 39000（耐受型）来标准化在幼苗期获取获得性耐受性状的方法。与快速胁迫相比，经历逐渐胁迫进展的幼苗在两种基因型中均表现出更高的恢复能力和更低的自由基积累。此外，使用逐渐胁迫进展方案，利用一组17种不同的水稻基因型，研究了开花期获得性耐受的作用。在这些基因型中观察到自由基产生和清除方面存在显著差异。这些参数与产量属性的关联表明，能够控制细胞内自由基水平的基因型在胁迫下能够保持较高的小穗育性，从而实现高产。这项研究除了强调获得性耐受的重要性外，还解释了一种高通量表型分析方法，该方法显著克服了评估这一重要干旱适应机制中遗传变异的方法学限制。
