Abstract

Photosynthesis, an indispensable biological process of plants, produces organic substances for plant growth, during which photorespiration occurs to oxidize carbohydrates to achieve homeostasis. Although the molecular mechanism underlying photosynthesis and photorespiration has been widely explored, the crosstalk between the two processes remains largely unknown. In this study, we isolated and characterized a T-DNA insertion mutant of tomato (Solanum lycopersicum) named yellow leaf (yl) with yellowish leaves, retarded growth, and chloroplast collapse that hampered both photosynthesis and photorespiration. Genetic and expression analyses demonstrated that the phenotype of yl was caused by a loss-of-function mutation resulting from a single-copy T-DNA insertion in chaperonin 60α1 (SlCPN60α1). SlCPN60α1 showed high expression levels in leaves and was located in both chloroplasts and mitochondria. Silencing of SlCPN60α1using virus-induced gene silencing and RNA interference mimicked the phenotype of yl. Results of two-dimensional electrophoresis and yeast two-hybrid assays suggest that SlCPN60α1 potentially interacts with proteins that are involved in chlorophyll synthesis, photosynthetic electron transport, and the Calvin cycle, and further affect photosynthesis. Moreover, SlCPN60α1 directly interacted with serine hydroxymethyltransferase (SlSHMT1) in mitochondria, thereby regulating photorespiration in tomato. This study outlines the importance of SlCPN60α1 for both photosynthesis and photorespiration, and provides molecular insights towards plant genetic improvement.

中文翻译：

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伴侣蛋白60蛋白SlCpn60α1调节番茄的光合作用和光呼吸。

摘要

光合作用是植物不可或缺的生物过程，会产生用于植物生长的有机物质，在此过程中，发生光呼吸作用以氧化碳水化合物以实现体内平衡。尽管已经广泛探索了光合作用和光呼吸的潜在分子机制，但这两个过程之间的串扰仍然未知。在这项研究中，我们分离并鉴定了番茄的T-DNA插入突变体（Solanum lycopersicum），该突变体名为黄叶（yl），叶片微黄，生长缓慢，叶绿体塌陷，阻碍了光合作用和光呼吸作用。遗传和表达分析表明，yl的表型这是由于伴侣蛋白60α1（S1CPN60α1）中单拷贝T-DNA插入导致的功能丧失突变引起的。S1CPN60α1在叶中显示高表达水平，并且位于叶绿体和线粒体中。使用病毒诱导的基因沉默和RNA干扰沉默SlCPN60α1模仿yl的表型。二维电泳和酵母双杂交检测结果表明，SlCPN60α1可能与参与叶绿素合成，光合电子传递和卡尔文循环的蛋白质相互作用，并进一步影响光合作用。此外，SlCPN60α1与线粒体中的丝氨酸羟甲基转移酶（SlSHMT1）直接相互作用，从而调节番茄的光呼吸。这项研究概述了SlCPN60α1对于光合作用和光呼吸的重要性，并提供了对植物遗传改良的分子见解。