Abstract
BackgroundsThe 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.ResultsWheat 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 H2O2 accumulation and O2− 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.ConclusionsOur results from chloroplast proteomics extend the understanding of the mechanisms employed by exogenous ALA to defend against drought stress in wheat.
Highlights
IntroductionWheat plants often suffer from drought stress throughout the whole growth stage, which causes serious physiological and biochemical damage, and as a result, the yield is reduced [1]
Wheat (Triticum aestivum L.) is one of the most important crops worldwide
When exogenous aminolevulinic acid (ALA) was pre-treated on wheat leaves, the osmotic potential decreased by 21% compared to that under drought stress alone, while the relative water content (RWC) and chlorophyll contents increased by 24 and 25%, respectively
Summary
Wheat plants often suffer from drought stress throughout the whole growth stage, which causes serious physiological and biochemical damage, and as a result, the yield is reduced [1]. Plant chloroplasts are one of the most sensitive components to drought stress. Wheat plants cannot sustain a normal performance to provide sufficient photosynthetic products to the plant unless the photosynthetic functions are adequately protected [3]. Sustaining plant chloroplast photosynthetic function under drought stress requires the regulation of chloroplast proteins. In reports from past decades, some proteins that sustain plant chloroplast photosynthetic function under drought stress have been characterized. Limited reports have shown that the translation, phosphorylation, and translocation of chloroplast protein play an important role in the sustainment of photosynthetic function under drought conditions
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