The extra-ribosomal functions of ribosomal proteins RPL6 and RPL23a in stress-responsiveness have emanated from our previous studies on activation tagged mutants of rice screened for water-use efficiency (Moin et al., 2016a). In the present study, we functionally validated the RPL6, a Ribosomal Protein Large subunit member for salt stress tolerance in rice. The overexpression of RPL6 resulted in tolerance to moderate (150 mM) to high (200 mM) levels of salt (NaCl) in rice. The transgenic rice plants expressing RPL6 constitutively showed better phenotypic and physiological responses with high quantum efficiency, accumulation of more chlorophyll and proline contents, and an overall increase in seed yield compared with the wild type in salt stress treatments. An iTRAQ-based comparative proteomic analysis revealed the high expression of about 333 proteins among the 4,378 DEPs in a selected overexpression line of RPL6 treated with 200 mM of NaCl. The functional analysis showed that these highly expressed proteins (HEPs) are involved in photosynthesis, ribosome and chloroplast biogenesis, ion transportation, transcription and translation regulation, phytohormone and secondary metabolite signal transduction. An in silico network analysis of HEPs predicted that RPL6 binds with translation-related proteins and helicases, which coordinately affects the activities of a comprehensive signaling network, thereby inducing tolerance and promoting growth and yield in response to salt stress. Our overall findings identified a novel candidate, RPL6 whose characterization contributed to the existing knowledge on the complexity of salt tolerance mechanism in plants.

中文翻译：

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核糖体蛋白大亚基RPL6调节水稻的耐盐性

核糖体蛋白RPL6和RPL23a在胁迫响应中的核糖体外功能源于我们先前对筛选的水稻水分利用效率活化标签突变体的研究（Moin等人，2016a）。在本研究中，我们在功能上验证了RPL6（核糖体蛋白大亚基成员）对水稻盐胁迫的耐受性。RPL6的过表达导致水稻对中等水平（150 mM）到高水平（200 mM）盐（NaCl）的耐受性。组成型表达RPL6的转基因水稻植株在盐胁迫处理中表现出更好的表型和生理学响应，具有较高的量子效率，积累了更多的叶绿素和脯氨酸含量，种子产量总体上比野生型提高。基于iTRAQ的比较蛋白质组学分析显示，在200mM NaCl处理的RPL6选定过表达系中，在4378个DEP中约333个蛋白质高表达。功能分析表明，这些高表达蛋白（HEP）参与光合作用，核糖体和叶绿体的生物发生，离子转运，转录和翻译调节，植物激素和次级代谢产物信号转导。对HEP进行的计算机网络分析预测，RPL6与翻译相关的蛋白质和解旋酶结合，从而协调地影响综合信号网络的活动，从而诱导耐受性并促进盐胁迫下的生长和产量。我们的整体发现确定了一个新颖的候选人，