Drought is the main constrain for crops worldwide, however, the effects of recurrent water deficit remains still hidden. We analysed two rice genotypes, 'BRS-Querência' (lowlands) and 'AN-Cambará' (uplands), after seven days of recurrent drought followed by 24 h of rehydration, hypothesizing that genotypes grown in regions with different water availabilities respond differently to water deficits, and that a previous exposure to stress could alter abscisic acid (ABA) metabolism. The results showed that both genotypes reduced stomatal conductance and increased ABA concentration. After rehydration, the ABA levels decreased, mainly in the plants of BRS-Querência subjected to recurrent stress. However, the levels of ABA were higher in plants in recurrent water deficit compared to non-recurrent stress plants in both genotypes. Remarkably in the lowland genotype, the ABA glucosyl-ester (ABA-GE) concentration increased after recovery in the plants under recurrent stress. Regarding of gene expression, the genes associated in ABA biosynthesis with the highest expression levels were NCED2, NCED3, NCED4 and AAO2. However, 'AN-Cambará' showed less transcriptional activation. Taking into account the genes involved in ABA catabolism, ABAH1 appears to play an important role related to the recurrent stress in upland plants. These results indicate that one of the factors that can promote greater tolerance for the upland genotype is the tradeoff between ABA and ABA-GE when plants are subjected to water deficits. In addition, they indicate that abscisic acid metabolism is altered due to the genotype (upland or lowland) and pre-exposure to stress can also modify adaptive responses in rice varieties (recurrent stress). This article is protected by copyright. All rights reserved.

中文翻译：

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两种不同的水稻基因型中脱落酸的代谢反复出现缺水

干旱是世界范围内农作物的主要制约因素，然而，经常性缺水的影响仍然隐藏。我们分析了两种水稻基因型，“BRS-Querência”（低地）和“AN-Cambará”（高地），经过 7 天的反复干旱和 24 小时的补水，假设生长在不同水资源可用性地区的基因型对缺水，并且先前暴露于压力可能会改变脱落酸（ABA）代谢。结果表明，两种基因型都降低了气孔导度并增加了 ABA 浓度。再水化后，ABA 水平下降，主要是在受到反复胁迫的 BRS-Querência 植物中。然而，与两种基因型的非反复胁迫植物相比，反复缺水植物的 ABA 水平更高。值得注意的是，在低地基因型中，植物在反复胁迫下恢复后 ABA 葡萄糖基酯 (ABA-GE) 浓度增加。在基因表达方面，与ABA生物合成相关的基因表达水平最高的是NCED2、NCED3、NCED4和AAO2。然而，“AN-Cambará”显示出较少的转录激活。考虑到参与 ABA 分解代谢的基因，ABAH1 似乎在与陆地植物的反复胁迫有关的重要作用。这些结果表明，当植物遭受水分亏缺时，可以促进对旱地基因型更大耐受性的因素之一是 ABA 和 ABA-GE 之间的权衡。此外，他们表明脱落酸代谢因基因型（高地或低地）而改变，预先暴露于胁迫也可以改变水稻品种的适应性反应（反复胁迫）。本文受版权保护。版权所有。