Trichoderma harzianum Enhances Antioxidant Defense of Tomato Seedlings and Resistance to Water Deficit
Trichoderma harzianum Enhances Antioxidant Defense of Tomato Seedlings and Resistance to Water Deficit
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DOI：
10.1094/mpmi-09-11-0240
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发表时间：
2012-09-01
影响因子：
3.5
通讯作者：
Harman, Gary E.
中科院分区：
文献类型：
--
作者：
Mastouri, Fatemeh;Bjoerkman, Thomas;Harman, Gary E.
木霉属的一些植物共生菌株定殖于根部并诱导植物基因表达的深刻变化，从而导致生长增强，特别是在生物和非生物胁迫下。在这项研究中，我们验证了T。哈茨菌T22定殖是抗氧化防御机制。在确定菌株T22调节编码抗氧化酶的基因的表达后，研究了番茄幼苗对T22定殖和水分亏缺的抗氧化防御状态。总抗坏血酸或谷胱甘肽水平不受任何刺激，但在水分亏缺，抗氧化剂池变得更加氧化（还原氧化形式的比例较低），而殖民植物保持氧化还原状态高或高于未受压力和未处理的植物。增强的氧化还原状态的殖民植物可以解释其较高的抗坏血酸和谷胱甘肽回收酶的活性，超氧化物歧化酶，过氧化氢酶，抗坏血酸过氧化物酶的活性较高，在整个实验中的根和地上部。类似的酶诱导在非殖民化的植物响应水分亏缺胁迫，但在较低的程度上相比，殖民化的植物。这种协调的增强活性的活性氧（ROS）清除途径在殖民地植物响应压力支持的假设，增强抗性的殖民地植物水分亏缺至少部分是由于更高的能力，以清除ROS和再循环氧化抗坏血酸和谷胱甘肽，一种机制，预计将提高耐受性非生物和生物胁迫。
Some plant-symbiotic strains of the genus Trichoderma colonize roots and induce profound changes in plant gene expression that lead to enhanced growth, especially under biotic and abiotic stresses. In this study, we tested the hypothesis that one of the protective mechanisms enhanced by T. harzianum T22 colonization is the antioxidant defense mechanism. Having established that strain T22 modulates the expression of the genes encoding antioxidant enzymes, the status of antioxidant defense of tomato seedlings in response to colonization by T22 and water deficit was investigated. Total ascorbate or glutathione levels were not affected by either stimuli, but under water deficit, antioxidant pools became more oxidized (lower ratios of reduced to oxidized forms), whereas colonized plants maintained redox state as high as or higher than unstressed and untreated plants. The enhanced redox state of colonized plants could be explained by their higher activity of ascorbate and glutathione-recycling enzymes, higher activity of superoxide dismutase, catalase, and ascorbate peroxidase, in both root and shoot throughout the experiment. Similar enzymes were induced in uncolonized plants in response to water-deficit stress but to a lower extent when compared with colonized plants. This orchestrated enhancement in activity of reactive oxygen species (ROS)-scavenging pathways in colonized plants in response to stress supports the hypothesis that enhanced resistance of colonized plants to water deficit is at least partly due to higher capacity to scavenge ROS and recycle oxidized ascorbate and glutathione, a mechanism that is expected to enhance tolerance to abiotic and biotic stresses.