Agricultural College of Guangxi University, Nanning, 530005, China.
State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Nanning, 530005, China.
Sci Rep. 2020 Apr 24;10(1):6968. doi: 10.1038/s41598-020-63809-8.
The antioxidant mechanism is crucial for resisting oxidative damage induced by drought stress in plants. Different antioxidant mechanisms may contribute to the tolerance of cassava to drought stress, but for a specific genotype, the response is still unknown. The objective of this study was to investigate antioxidant response and physiological changes of four cassava genotypes under water stress conditions, by keeping the soil moisture content as 80% (control), 50% (medium), 20% (severe) of field capacity for a week. Genotypes RS01 and SC124 were keeping higher relative water content (RWC) and relative chlorophyll content (SPAD value) and less affected by oxidative stress than SC205 and GR4 under drought stress. RS01 just showed slight membrane damage and oxidative stress even under severe drought conditions. A principal component analysis showed that cassava plant water status was closely related to the antioxidant mechanism. Antioxidant response in genotypes RS01 and SC124 under drought stress might attribute to the increased accumulation of ascorbate (AsA) and glutathione (GSH) content and higher superoxide dismutase (SOD) and catalase (CAT) activities, which explained by the up-regulation of Mn-SOD and CAT genes. However, Genotypes SC205 and GR4 mainly depended on the accumulation of total phenolics (TP) and increased glutathione reductase (GR) activity, which attribute to the up-regulation of the GR gene. Our findings could provide vital knowledge for refining the tactics of cultivation and molecular breeding with drought avoidance in cassava.
抗氧化机制对于植物抵抗干旱胁迫引起的氧化损伤至关重要。不同的抗氧化机制可能有助于木薯耐受干旱胁迫，但对于特定基因型，其响应仍不清楚。本研究旨在通过将土壤含水量保持在田间持水量的 80%（对照）、50%（中度）和 20%（重度），持续一周，研究四个木薯基因型在水分胁迫条件下的抗氧化响应和生理变化。在干旱胁迫下，基因型 RS01 和 SC124 保持较高的相对水含量（RWC）和相对叶绿素含量（SPAD 值），受氧化应激的影响较小，而 SC205 和 GR4 则较小。RS01 甚至在严重干旱条件下仅表现出轻微的膜损伤和氧化应激。主成分分析表明，木薯植物的水分状况与抗氧化机制密切相关。干旱胁迫下基因型 RS01 和 SC124 的抗氧化响应可能归因于抗坏血酸（AsA）和谷胱甘肽（GSH）含量的增加以及超氧化物歧化酶（SOD）和过氧化氢酶（CAT）活性的提高，这可以通过 Mn-SOD 和 CAT 基因的上调来解释。然而，基因型 SC205 和 GR4 主要依赖于总酚（TP）的积累和谷胱甘肽还原酶（GR）活性的增加，这归因于 GR 基因的上调。我们的研究结果可为木薯栽培和分子育种策略的制定提供重要知识，以实现抗旱性。
