School of Drought Stress Management, ICAR-National Institute of Abiotic Stress Management, Pune, India.
Division of Basic Sciences, ICAR-Indian Institute of Pulse Research, Kanpur, India.
Physiol Plant. 2023 Nov-Dec;175(6):e14102. doi: 10.1111/ppl.14102.
Drought hampers global rice production. Abscisic acid (ABA) plays versatile roles under different environmental stresses. While the link between drought and ABA is known, its effect on ABA biosynthesis genes and metabolites is unclear. This study explored the impact of drought on various metabolites, namely beta-carotene, zeaxanthin, antheraxanthin, violaxanthin, neoxanthin, and candidate genes viz. zeaxanthin epoxidase (ZEP) and 9-cis epoxycarotenoid dioxygenase (NCED) of ABA biosynthesis pathway in rice cultivars (N22 and IR64) at anthesis {65 DAT (Days after transplanting)} with different stress levels. In stressed plants, zeaxanthin significantly increased (92%), while the concentration of beta-carotene, antheraxanthin, violaxanthin and neoxanthin decreased as drought stress progressed. The concentration of metabolites in roots was notably lower than in leaves in both genotypes. The ZEP expression was upregulated in roots (8.24-fold) under drought stress. Among five NCED isoforms, NCED3 showed significant upregulation (7.29-fold) in leaf and root tissue. NCED1 was significantly downregulated as stress progressed and was negatively correlated with ABA accumulation. NCED2, NCED4 and NCED5 showed no significant change in their expression. Drying and rolling of rice leaves was observed after imparting drought stress. The findings revealed that drought stress significantly influenced the expression of candidate genes and the concentration of metabolites of the ABA biosynthesis pathway. There was a significantly higher accumulation of ABA in N22 leaves (47%) and roots (30%) compared to IR64. The N22, a drought-tolerant genotype, exhibited significantly higher concentrations of intermediates and demonstrated increased expression of ZEP and NCED3, potentially contributing to its resilience against drought.
干旱影响全球水稻产量。脱落酸（ABA）在不同环境胁迫下发挥多种作用。虽然已经知道干旱和 ABA 之间的联系，但它对 ABA 生物合成基因和代谢物的影响尚不清楚。本研究在抽穗期（移栽后 65 天），以不同胁迫水平下，研究了干旱对水稻品种（N22 和 IR64）中各种代谢物（β-胡萝卜素、玉米黄质、花药黄质、紫黄质、新黄质和 ABA 生物合成途径的候选基因，如玉米黄质环氧化酶（ZEP）和 9-顺式环氧类胡萝卜素双加氧酶（NCED）的影响。在胁迫下的植物中，玉米黄质显著增加（92%），而随着干旱胁迫的发展，β-胡萝卜素、花药黄质、紫黄质和新黄质的浓度降低。在两种基因型中，根中的代谢物浓度明显低于叶片中的浓度。在干旱胁迫下，根中的 ZEP 表达上调（8.24 倍）。在五个 NCED 同工型中，NCED3 在叶片和根组织中显著上调（7.29 倍）。随着胁迫的发展，NCED1 的表达显著下调，与 ABA 积累呈负相关。NCED2、NCED4 和 NCED5 的表达没有明显变化。施加干旱胁迫后，观察到水稻叶片的干燥和卷曲。研究结果表明，干旱胁迫显著影响候选基因的表达和 ABA 生物合成途径的代谢物浓度。与 IR64 相比，N22 叶片（47%）和根（30%）中 ABA 的积累显著增加。N22 是一种耐旱基因型，其中间产物浓度显著升高，并表现出 ZEP 和 NCED3 的表达增加，这可能有助于其对干旱的适应能力。
