Abstract
BackgroundKernel development and starch formation are the primary determinants of maize yield and quality, which are considerably influenced by drought stress. To clarify the response of maize kernel to drought stress, we established well-watered (WW) and water-stressed (WS) conditions at 1–30 days after pollination (dap) on waxy maize (Zea mays L. sinensis Kulesh).ResultsKernel development, starch accumulation, and activities of starch biosynthetic enzymes were significantly reduced by drought stress. The morphology of starch granules changed, whereas the grain filling rate was accelerated. A comparative proteomics approach was applied to analyze the proteome change in kernels under two treatments at 10 dap and 25 dap. Under the WS conditions, 487 and 465 differentially accumulated proteins (DAPs) were identified at 10 dap and 25 dap, respectively. Drought induced the downregulation of proteins involved in the oxidation–reduction process and oxidoreductase, peroxidase, catalase, glutamine synthetase, abscisic acid stress ripening 1, and lipoxygenase, which might be an important reason for the effect of drought stress on kernel development. Notably, several proteins involved in waxy maize endosperm and starch biosynthesis were upregulated at early-kernel stage under WS conditions, which might have accelerated endosperm development and starch synthesis. Additionally, 17 and 11 common DAPs were sustained in the upregulated and downregulated DAP groups, respectively, at 10 dap and 25 dap. Among these 28 proteins, four maize homologs (i.e., A0A1D6H543, B4FTP0, B6SLJ0, and A0A1D6H5J5) were considered as candidate proteins that affected kernel development and drought stress response by comparing with the rice genome.ConclusionsThe proteomic changes caused by drought were highly correlated with kernel development and starch accumulation, which were closely related to the final yield and quality of waxy maize. Our results provided a foundation for the enhanced understanding of kernel development and starch formation in response to drought stress in waxy maize.
Highlights
Kernel development and starch formation are the primary determinants of maize yield and quality, which are considerably influenced by drought stress
Our results showed no difference in the starch content under two treatments at 10 dap, but the starch content under WS treatment was significantly higher than that under WW treatment at 15 dap (Fig. 1D)
Compared with WW, WS caused a significant decrease in starch accumulation from 20 to 30 dap (Fig. 1D)
Summary
Kernel development and starch formation are the primary determinants of maize yield and quality, which are considerably influenced by drought stress. Studies reported that DS during the grain-formation stage reduced the number of endosperm cells and starch granules, but increased the starch granule size [5, 12]. DS impedes starch synthesis by reducing the enzymatic activities related to starch biosynthesis, which leading to a decline in grain yield [15, 16]. These enzymes mainly include: (1) Sucrose phosphate synthase (SPS) is a key enzyme in the regulation of sucrose biosynthesis in source tissues [17]. Our understanding of drought response mechanisms during the grain-filling stage remains unclear
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