College of Life Sciences, Henan Agricultural University, No. 63, Nongye Rd., Zhengzhou, 450002, Henan Province, China.
College of Science, China Agricultural University, Beijing, 100193, China.
BMC Plant Biol. 2020 Mar 4;20(1):96. doi: 10.1186/s12870-020-2297-6.
The perturbance of chloroplast proteins is a major cause of photosynthesis inhibition under drought stress. The exogenous application of 5-aminolevulinic acid (ALA) mitigates the damage caused by drought stress, protecting plant growth and development, but the regulatory mechanism behind this process remains obscure.
Wheat seedlings were drought treated, and the iTRAQ-based proteomic approach was employed to assess the difference in chloroplast protein content caused by exogenous ALA. A total of 9499 peptides, which could be classified into 2442 protein groups, were identified with ≤0.01 FDR. Moreover, the contents of 87 chloroplast proteins was changed by drought stress alone compared to that of the drought-free control, while the contents of 469 was changed by exogenous ALA application under drought stress compared to that of drought stress alone. The Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis results suggested that the ALA pretreatment adjusted some biological pathways, such as metabolic pathways and pathways involved in photosynthesis and ribosomes, to enhance the drought resistance of chloroplasts. Furthermore, the drought-promoted HO accumulation and O production in chloroplasts were alleviated by the exogenous pretreatment of ALA, while peroxidase (POD) and glutathione peroxidase (GPX) activities were upregulated, which agreed with the chloroplast proteomic data. We suggested that ALA promoted reactive oxygen species (ROS) scavenging in chloroplasts by regulating enzymatic processes.
Our results from chloroplast proteomics extend the understanding of the mechanisms employed by exogenous ALA to defend against drought stress in wheat.
叶绿体蛋白的扰动是干旱胁迫下光合作用抑制的主要原因。外源 5-氨基乙酰丙酸（ALA）的应用减轻了干旱胁迫造成的损害，保护了植物的生长和发育，但这一过程的调节机制尚不清楚。
对小麦幼苗进行干旱处理，采用基于 iTRAQ 的蛋白质组学方法评估外源 ALA 引起的叶绿体蛋白含量差异。共鉴定到 9499 个肽段，可分为 2442 个蛋白质组，其 FDR 值均≤0.01。此外，与无干旱对照相比，干旱胁迫单独处理会改变 87 种叶绿体蛋白的含量，而与干旱胁迫单独处理相比，外源 ALA 处理会改变 469 种叶绿体蛋白的含量。GO 注释和京都基因与基因组百科全书（KEGG）分析结果表明，ALA 预处理调整了一些生物途径，如代谢途径以及光合作用和核糖体相关途径，以增强叶绿体的抗旱性。此外，外源 ALA 预处理减轻了干旱促进的叶绿体中 HO 的积累和 O 的产生，同时上调了过氧化物酶（POD）和谷胱甘肽过氧化物酶（GPX）的活性，这与叶绿体蛋白质组学数据一致。我们认为，ALA 通过调节酶促过程促进了叶绿体中活性氧（ROS）的清除。
我们从叶绿体蛋白质组学得到的结果扩展了对外源 ALA 抵御小麦干旱胁迫机制的理解。
