Osmolyte accumulation and antioxidant metabolism during germination of vigorous maize seeds subjected to water deficit

ABSTRACT. The objective of this work was to evaluate the alterations of antioxidant enzyme reserves and antioxidant enzymes during germination under water deficit in maize hybrids and to associate with seed vigor, determining the mechanisms related to tolerance for this stress. Two three-way maize hybrids were characterized by their vigor at different levels of water deficit induced by polyethylene glycol 6000. Next, the seeds were hydrated at different osmotic potentials (0.0, -0.3, and -0.9 MPa) and removed at different times to assess the levels of the total soluble protein, total soluble sugars, proline, starch, and antioxidant enzymes, such as superoxide dismutase, catalase and ascorbate peroxidase. The analysis of variance, Tukey test at 5% and principal component analysis (PCA) were used. The vigorous hybrid (HT1) was more efficient than the low vigor hybrid seeds (HT2) in mobilizing the total soluble protein during the initial stages of germination and the total soluble sugars before and after root protrusion under water deficit in addition to increasing the catalase activity at the different osmotic potentials that were assessed.

摘要。本研究旨在探究玉米杂交种在水分胁迫萌发阶段的抗氧化酶储备与抗氧化酶活性变化，将其与种子活力相关联，以明确该逆境胁迫下的耐受机制。本实验选取两个三交玉米杂交种，通过聚乙二醇6000（polyethylene glycol 6000）诱导生成不同梯度的水分胁迫，以种子活力为分级依据对其进行表征。随后，将种子置于不同渗透势（0.0、-0.3和-0.9 MPa）的溶液中进行水合处理，并于不同时间点取样，以检测总可溶性蛋白、总可溶性糖、脯氨酸、淀粉含量以及超氧化物歧化酶（superoxide dismutase）、过氧化氢酶（catalase）和抗坏血酸过氧化物酶（ascorbate peroxidase）等抗氧化酶的活性水平。本实验采用方差分析、5%显著性水平下的图基（Tukey）多重比较检验以及主成分分析（principal component analysis, PCA）进行数据统计分析。结果表明，在水分胁迫条件下，高活力杂交种（HT1）相较于低活力杂交种（HT2），在萌发初始阶段可更高效地动员总可溶性蛋白，且在根突出前后能更有效地调控总可溶性糖代谢；同时在各测试渗透势下，其过氧化氢酶活性均显著提升。