Hu Xiuli, Yang Yanfang, Gong Fangping, Zhang Dayong, Zhang Li, Wu Liuji, Li Chaohao, Wang Wei
State Key Laboratory of Wheat & Maize Crop Science, College of Life Science, College of Agronomy, Henan Agricultural University, Zhengzhou 450002, China.
Provincial Key Laboratory of Agrobiology, Jiangsu Academy of Agricultural Sciences, Institute of Biotechnology, Nanjing 210094, China.
J Proteomics. 2015 Feb 6;115:81-92. doi: 10.1016/j.jprot.2014.12.009. Epub 2014 Dec 23.
We recently demonstrated that chloroplast small HSP26 (sHSP26) is abundant in maize leaves under heat stress and potentially involved in maize heat tolerance. However, it largely remains unclear how sHSP26 functions in maize under heat stress. Here, 2-DE-based proteomics, RNA interference (RNAi), co-immunoprecipitation (Co-IP) and yeast two-hybrid (Y2H) were used to reveal chloroplast proteins interacting with sHSP26 and how sHSP26 functions under heat stress. After the silencing of sHSP26, a total of 45 protein spots from isolated protoplasts were greatly changed in abundance, of which 33 spots are chloroplastic. Co-IP revealed that nine proteins possibly associated with sHSP26. Y2H demonstrated that six chloroplast proteins interact with sHSP26 under heat stress. In particular, four proteins, including ATP synthase subunit β, chlorophyll a-b binding protein, oxygen-evolving enhancer protein 1 and photosystem I reaction center subunit IV, strongly interacted with sHSP26 and their abundance greatly declined after RNAi of sHSP26 under heat stress. In addition, H2O2 accumulation in the chloroplasts significantly increased the expression of sHSP26, and the suppression of sHSP26 expression significantly reduced the O2 evolution rate of photosystem II under heat stress. Overall, these findings demonstrate the relevance of sHSP26 in protecting maize chloroplasts under heat stress.
Maize is one of the most important crops worldwide. Frequent heat stress reduces significantly the yield and quality of maize. Our results demonstrated that sHSP26 improved maize chloroplast performance under heat stress by interacting with specific proteins. These findings are useful for understanding the mechanism of heat stress response and heat-tolerant molecular breeding in maize.
我们最近证明，叶绿体小热激蛋白26（sHSP26）在热胁迫下的玉米叶片中含量丰富，并可能参与玉米的耐热性。然而，在热胁迫下sHSP26在玉米中如何发挥作用在很大程度上仍不清楚。在此，基于双向电泳的蛋白质组学、RNA干扰（RNAi）、免疫共沉淀（Co-IP）和酵母双杂交（Y2H）被用于揭示与sHSP26相互作用的叶绿体蛋白以及sHSP26在热胁迫下如何发挥作用。在sHSP26沉默后，分离的原生质体中共有45个蛋白点的丰度发生了显著变化，其中33个点是叶绿体的。免疫共沉淀显示有9种蛋白质可能与sHSP26相关。酵母双杂交表明在热胁迫下有6种叶绿体蛋白与sHSP26相互作用。特别地，包括ATP合酶β亚基、叶绿素a-b结合蛋白、放氧增强蛋白1和光系统I反应中心亚基IV在内的4种蛋白质与sHSP26强烈相互作用，并且在热胁迫下sHSP26进行RNA干扰后它们的丰度大幅下降。此外，叶绿体中过氧化氢的积累显著增加了sHSP26的表达，而sHSP26表达的抑制显著降低了热胁迫下光系统II的放氧速率。总体而言，这些发现证明了sHSP26在热胁迫下保护玉米叶绿体的相关性。
玉米是全球最重要的作物之一。频繁的热胁迫显著降低了玉米的产量和品质。我们的结果表明，sHSP26通过与特定蛋白质相互作用改善了热胁迫下玉米叶绿体的性能。这些发现有助于理解玉米热胁迫响应机制和耐热分子育种。
