Metabolism of abscisic acid in two contrasting rice genotypes submitted to recurrent water deficit

Abstract

Drought is the main constrain for crops worldwide, however, the effects of recurrent water deficit remain still hidden. We analysed two rice genotypes, 'BRS-Querência' (lowlands) and 'AN-Cambará' (uplands), after 7 days of recurrent drought followed by 24 h of rehydration, hypothesising 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).

Differential Response of Two Tomato Genotypes, Wild Type cv. Ailsa Craig and Its ABA-Deficient Mutant flacca to Short-Termed Drought Cycles

“…Our result on the up-regulation of the NCED1 gene under water deprivation is in line with the observed ABA accumulation in tomato leaves (Figure 6). The up-regulation of NCEDs genes under drought has been demonstrated elsewhere [61,62,65,66]. We assume that the more pronounced expression of the NCED1 gene in WT observed in the 3rd drought cycle was mostly due to its de novo biosynthesis, while in the 1st and 2nd cycles the ABA was synthesized from its precursors and conjugates.…”

“…While the drought-induced ABA levels were restored during re-watering in WT in all cycles, in flacca a similar trend was observed only in the 2 nd drought episode. We suppose that some form of ABA conjugates could dominate at that particular stage as a backup for potential upcoming drought [61].…”

“…It has been recently shown that, under stress conditions, ROS are involved also in non-enzymatic conversion of ABA precursors to ABA, which might also contribute to the elevated ABA content in the ABA-deficient mutants [67,68]. However, ABA content and transcription intensity of the ABA-biosynthesis-related genes may not always be in correlation, as the level of ABA depends also on ABA's redistribution within the leaf and between root and shoot [61,69,70].…”

A Review on Kentucky Bluegrass Responses and Tolerance to Drought Stress

“…So far, the important physiological mechanism of plant adaptation to drought resistance is ABA (Abscisic acid) accumulation, the amount of the primary chemical of ABA can reach up to more than 50-fold in plants under drought conditions [46,47]. ABA is one of the most drastic changes observed hitherto in the concentration of a plant hormone responding to an environmental stimulus [37].…”

The role of priming and memory in rice environmental stress adaptation: Current knowledge and perspectives

“…(a) Physiological changes in rice leaf blade and root in response to abiotic stress priming. Drought stress‐primed leaf blade tissue (green panel) shows increased ABA signalling (Auler et al, 2021; Li et al, 2019; Rossatto et al, 2023) and greater stomatal conductance (Auler et al, 2021). Salt stress‐priming increases activity of the vacuolar Na + /H + exchanger 1 (OsNHX1) within the leaf blade (Sriskantharajah et al, 2020), which transports Na + from cytosol into vacuoles reducing the salt‐induced toxicity during future stress.…”