Field Crops Department/Faculty of Agriculture, Osmangazi University, Eskişehir, Turkey.
PeerJ. 2024 Aug 22;12:e17931. doi: 10.7717/peerj.17931. eCollection 2024.
Drought is the most significant factor limiting maize production, given that maize is a crop with a high water demand. Therefore, studies investigating the mechanisms underlying the drought tolerance of maize are of great importance. There are no studies comparing drought tolerance among economically important subspecies of maize. This study aimed to reveal the differences between the physio-biochemical, enzymatic, and molecular mechanisms of drought tolerance in dent (), popcorn (), and sugar () maize under control (no-stress), moderate, and severe drought stress.
Three distinct irrigation regimes were employed to assess the impact of varying levels of drought stress on maize plants at the V14 growth stage. These included normal irrigation (80% field capacity), moderate drought (50% field capacity), and severe drought (30% field capacity). All plants were grown under controlled conditions. The following parameters were analyzed: leaf relative water content (RWC), loss of turgidity (LOT), proline (PRO) and soluble protein (SPR) contents, membrane durability index (MDI), malondialdehyde (MDA), and hydrogen peroxide (HO) content, the antioxidant enzyme activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT). Additionally, the expression of heat shock proteins (HSPs) was examined at the transcriptional and translational levels.
The effects of severe drought were more pronounced in sugar maize, which had a relatively high loss of RWC and turgor, membrane damage, enzyme activities, and HSP90 gene expression. Dent maize, which is capable of maintaining its RWC and turgor in both moderate and severe droughts, and employs its defense mechanism effectively by maintaining antioxidant enzyme activities at a certain level despite less MDA and HO accumulation, exhibited relatively high drought tolerance. Despite the high levels of MDA and HO in popcorn maize, the up-regulation of antioxidant enzyme activities and HSP70 gene and protein expression indicated that the drought coping mechanism is activated. In particular, the positive correlation of HSP70 with PRO and HSP90 with enzyme activities is a significant result for studies examining the relationships between HSPs and other stress response systems. The discrepancies between the transcriptional and translational findings provide an opportunity for more comprehensive investigations into the role of HSPs in stress conditions.
由于玉米是一种高耗水作物，干旱是限制玉米产量的最重要因素。因此，研究玉米耐旱性的机制非常重要。目前还没有研究比较玉米经济重要亚种之间的耐旱性。本研究旨在揭示马齿型（）、爆裂型（）和甜质型（）玉米在对照（无胁迫）、中度和重度干旱胁迫下的生理生化、酶和分子耐旱机制之间的差异。
在 V14 生长阶段，采用三种不同的灌溉制度来评估不同程度干旱胁迫对玉米植株的影响。这些制度包括正常灌溉（田间持水量的 80%）、中度干旱（田间持水量的 50%）和重度干旱（田间持水量的 30%）。所有植物均在受控条件下生长。分析了以下参数：叶片相对水含量（RWC）、膨压丧失（LOT）、脯氨酸（PRO）和可溶性蛋白（SPR）含量、膜耐久性指数（MDI）、丙二醛（MDA）和过氧化氢（HO）含量、超氧化物歧化酶（SOD）、抗坏血酸过氧化物酶（APX）和过氧化氢酶（CAT）的抗氧化酶活性。此外，还检测了热休克蛋白（HSPs）在转录和翻译水平的表达。
重度干旱对甜质玉米的影响更为明显，其 RWC 和膨压丧失较高，膜损伤、酶活性和 HSP90 基因表达较高。马齿型玉米在中度和重度干旱下均能维持其 RWC 和膨压，通过维持抗氧化酶活性在一定水平，有效利用其防御机制，尽管 MDA 和 HO 积累较少，表现出较高的耐旱性。尽管爆裂玉米的 MDA 和 HO 水平较高，但抗氧化酶活性和 HSP70 基因和蛋白表达的上调表明干旱应对机制被激活。特别是 HSP70 与 PRO 和 HSP90 与酶活性的正相关是研究 HSPs 与其他应激反应系统之间关系的重要结果。转录和翻译结果之间的差异为更全面地研究 HSPs 在应激条件下的作用提供了机会。
