College of Grassland Science, Nanjing Agricultural University, Nanjing, 210095, China.
State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangdong Engineering Research Center for Grassland Science, College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China.
Plant Cell Rep. 2020 Jul;39(7):851-860. doi: 10.1007/s00299-020-02534-y. Epub 2020 Apr 2.
MfLEA3 is involved in protection of catalase activity and confers multiple abiotic stress tolerance. Late embryogenesis abundant (LEA) proteins are involved in plant growth, development and abiotic stress tolerance. A member of group 3 LEA proteins from Medicago sativa subsp. falcata (L.) Arcang, MfLEA3, was investigated in the study. MfLEA3 transcript was induced in response to cold, dehydration, and abscisic acid (ABA), while the cold-induced transcript of MfLEA3 was blocked by pretreatment with inhibitor of ABA synthesis. Constitutive expression of MfLEA3 led to enhanced tolerance to cold, drought, and high-light stress in transgenic tobacco plants. Compared to accumulated reactive oxygen species (ROS) in the wild-type in response to treatments with low temperature, drought, and high light, ROS were not accumulated in transgenic plants. Superoxide dismutase, catalase (CAT), and ascorbate-peroxidase activities were increased in all plants after treatments with the above stresses, while higher CAT activity was maintained in transgenic plants compared with wild-type. However, transcript level of CAT-encoding genes including CAT1, CAT2, and CAT3 showed no significant difference between transgenic plants and wild-type, indicating that the higher CAT activity was not associated with its gene expression. ABA sensitivity and transcripts of several ABA and stress-responsive genes showed no difference between transgenic plant and wild-type, indicating that ABA signaling was not affected by constitutive expression of MfLEA3. The results suggest that MfLEA3 may be involved in the protection of CAT activity and confers multiple abiotic stress tolerance.
MfLEA3 参与保护过氧化氢酶活性并赋予多种非生物胁迫耐受性。晚期胚胎丰富（LEA）蛋白参与植物生长、发育和非生物胁迫耐受性。研究中调查了来自 Medicago sativa subsp. falcata (L.) Arcang 的第 3 组 LEA 蛋白的一个成员 MfLEA3。MfLEA3 转录物响应冷、脱水和脱落酸（ABA）诱导，而 MfLEA3 的冷诱导转录物被 ABA 合成抑制剂预处理所阻断。MfLEA3 的组成型表达导致转基因烟草植物对冷、干旱和高光胁迫的耐受性增强。与野生型在低温、干旱和高光处理下积累的活性氧（ROS）相比，转基因植物中没有积累 ROS。超氧化物歧化酶、过氧化氢酶（CAT）和抗坏血酸过氧化物酶活性在所有处理后均增加，而与野生型相比，转基因植物中维持更高的 CAT 活性。然而，CAT 编码基因（包括 CAT1、CAT2 和 CAT3）的转录本在转基因植物和野生型之间没有显著差异，表明更高的 CAT 活性与其基因表达无关。ABA 敏感性和几种 ABA 和应激响应基因的转录本在转基因植物和野生型之间没有差异，表明 ABA 信号不受 MfLEA3 的组成型表达影响。结果表明，MfLEA3 可能参与保护 CAT 活性并赋予多种非生物胁迫耐受性。
