Abstract
Water deficit and rehydration frequently occur during wheat cultivation. Previous investigations focused on the water deficit and many drought-responsive genes have been identified in winter wheat. However, the hormone-related metabolic responses and de-peroxidative activities associated with rehydration are largely unknown. In this study, leaves of two winter wheat cultivars, “Hengguan35” (HG, drought-tolerant cultivar) and “Shinong086” (SN, drought-sensitive cultivar), were used to investigate water deficit and the post-rehydration process. Rehydration significantly promoted wheat growth and postponed spike development. Quantifications of antioxidant enzymes, osmotic stress-related substances, and phytohormones revealed that rehydration alleviated the peroxidation and osmotic stress caused by water deficit in both cultivars. The wheat cultivar HG showed a better rehydration-compensation phenotype than SN. Phytohormones, including abscisic acid, gibberellin (GA), jasmonic acid (JA), and salicylic acid (SA), were detected using high-performance liquid chromatography and shown to be responsible for the rehydration process. A transcriptome analysis showed that differentially expressed genes related to rehydration were enriched in hormone metabolism- and de-peroxidative stress-related pathways. Suppression of genes associated with abscisic acid signaling transduction were much stronger in HG than in SN upon rehydration treatment. HG also kept a more balanced expression of genes involved in reactive oxygen species pathway than SN. In conclusion, we clarified the hormonal changes and transcriptional profiles of drought-resistant and -sensitive winter wheat cultivars in response to drought and rehydration, and we provided insights into the molecular processes involved in rehydration compensation.
Highlights
Wheat is an important global staple crop vulnerable to climate conditions and its yield is associated with water supply during the cultivation season (Araya et al, 2019; Wang et al, 2021)
To investigate whether there is an association between rehydration compensation and drought tolerance, we compared the growth of drought-tolerant cultivar “HG” and the drought-sensitive cultivar “SN” under rehydration and drought-stress conditions (Figure 1)
Plant heights significantly increased after the rehydration treatment, and the drought-tolerant cultivar showed a pronounced faster growth than the drought-sensitive cultivar (Figure 2B)
Summary
Wheat is an important global staple crop vulnerable to climate conditions and its yield is associated with water supply during the cultivation season (Araya et al, 2019; Wang et al, 2021). Rehydration compensation is a common phenomenon during crop cultivation. In certain developmental periods of crops, water limited irrigation triggers a compensatory promotion of growth after release of the drought stress, which simultaneously improves water use efficiency, yield, and quality of crops (Araya et al, 2019). An efficient rehydration compensation is dependent on a good balancing between “self-protection” of crops upon drought stress and “compensation” after rehydration treatment (Zhao et al, 2020). It is crucial to clarify the physiological changes and molecular mechanisms associated with both water deficit and rehydration in wheat (Lopes et al, 2012; Song et al, 2017)
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