蛋白质组学分析揭示水稻地上部对缺铁和高铁胁迫的响应

Proteomic Dissection of the Rice Shoots in Response to Iron Deficiency and Excess

铁在矿质土壤中含量丰富,但在中性和碱性土壤中大多以不易被植物吸收利用的氧化物或氢氧化物形式存在;稻田土壤在淹水条件时氧化还原电位较低,大量铁以易被植物吸收利用的亚铁形式存在。土壤中铁的生物有效性过低或过高均会导致植物的生长发育受阻。本研究对缺铁(0μmol·L^(-1))、铁充足(40μmol·L^(-1))和高铁(350和500μmol·L^(-1))条件生长的水稻地上部进行了非标记蛋白质组学分析。结果显示,与铁充足条件相比,缺铁和两种浓度的高铁胁迫水稻中分别有130、157和118个蛋白质的丰度发生显著变化。基因本体富集分析显示,缺铁和高铁胁迫下的差异蛋白在初级代谢过程、有机氮化合物代谢过程、蛋白质代谢过程和细胞成分组织或生物发生等生物学过程均显著富集;差异蛋白还参与核糖体、光合作用和氧化磷酸化等代谢途径。缺铁胁迫显著影响参与苯丙烷类物质和辅助因子生物合成的蛋白质丰度,而高铁胁迫则引起氨基酸生物合成过程的蛋白质丰度发生显著变化。本研究发掘到一系列可用于水稻铁高效育种工作的候选蛋白,还发现了一些功能未知的差异蛋白可作为后续水稻铁胁迫响应的研究目标,同时为理解植物应对铁胁迫的完整响应网络提供了补充信息。

【Objective】In calcareous soils,iron(Fe)generally exists in the form of oxides or hydroxides,which is not conducive to plant absorption and utilization,thus frequently causing Fe deficiency in plants.In flooded acidic soils,such as paddy soil,due to conditions of irrigation and drainage and alternate cultivation of water and drought,the redox potential of the soil is low and ferric Fe is reduced to be ferrous.The ferrous Fe is readily absorbed and utilized,resulting in excessive Fe absorption by plants.Fe deficiency and excess are limiting factors affecting rice yield and quality.Fe deficiency leads to chlorosis and reduces plant growth while Fe overload is toxic for plants,with a typical symptom of leaf bronzing.Several transcriptome analyses have been performed to investigate the responses under Fe stress.However,a comprehensive dissection of the entire Fe-responsive profile at the protein level is still lacking.It is necessary to analyze the rice responses under Fe deficiency and Fe excess using proteomic analysis.【Method】In this study,a label-free proteomic analysis was performed on rice shoots grown in Fe-deficient(0μmol·L^(-1)),Fe-sufficient(40μmol·L^(-1)),and Fe-excess(350 and 500μmol·L^(-1))conditions.【Result】Results showed that 130,157 and 118 differentially accumulated proteins(DAPs)were identified under Fe deficiency and two concentrations of Fe excess stresses,respectively,compared with Fe sufficient conditions.Gene ontology enrichment analysis of the DAPs revealed that primary metabolic process,organonitrogen compound metabolic process,response to stimulus,and oxidative stress responses were significantly enriched under both Fe deficiency and excess stresses.Kyoto Encyclopedia of Genes and Genomes(KEGG)enrichment analysis showed that DAPs under Fe deficiency and Fe excess were commonly enriched in metabolic processes like the ribosome,photosynthesis,and oxidative phosphorylation.Notably,the abundance of proteins involved in phenylpropanoid biosynthesis and biosynthesis of cofactors was mainly affected by Fe deficiency,while the abundance of proteins involved in the biosynthesis of amino acids was mainly influenced by Fe excess.Under Fe excess stress,the abundance of enzymes involved in amino acid metabolism was decreased,indicating a reduction in the content of plant-synthesized amino acids.However,the increased abundance of transketolase involved in photosynthesis and secondary metabolism probably reduced the inhibitory effect induced by Fe stress.Ribosomal proteins S16,Os03g0798600 and RPL17 may play important roles in response to Fe deficiency and Fe excess stresses,but the exact functions of these proteins under Fe stress are still unknown.Several novel proteins which may play potential roles in rice Fe homeostasis were also predicted in this study.【Conclusion】Overall,these results indicate both Fe deficiency and Fe excess stresses affected photosynthesis and ribosomal metabolism.The synthesis of phenylpropane was mainly affected by Fe deficiency,while amino acid metabolism was mainly affected by Fe excess in the shoots of rice.The findings will provide some information for the exploration of key factors for the efficient absorption and utilization of Fe.