Roy Ansuman, Sahoo Dinabandhu, Tripathy Baishnab C
School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India.
Department of Botany, University of Delhi, New Delhi, India.
Protoplasma. 2016 Mar;253(2):393-402. doi: 10.1007/s00709-015-0818-1. Epub 2015 Apr 24.
Red light perceived by the shoot bottom suppresses photomorphogenesis in rice seedlings mediated by phytochrome A. Shoots of these seedlings grown in red light having their shoot bottom exposed were deficient in chlorophyll and accumulated high concentration of trans-zeatin riboside. However, reduced presence of isopentynyl adenosine, dihydrozeatin riboside was observed in shoots of red-light-grown non-green seedlings in comparison to green seedling. The message abundance of cytokinin receptor (OsHK5), transporters (OsENT1, OsENT2), and response regulators (OsRR4, OsRR10) was downregulated in these red-light-grown non-green seedlings. Attenuation of greening process was reversed by application of exogenous cytokinin analogue, benzyladenine, or supplementing red light with blue light. In the same vein, the suppression of gene expression of cytokinin receptor, transporters, and type-A response regulators was reversed in red-light-grown seedlings treated with benzyladenine suggesting that the disarrayed cytokinin (CK) signaling cascade is responsible for non-greening of seedlings grown in red light. The reversal of red-light-induced suppression of photomorphogenesis by blue light and benzyladenine demonstrates the interaction of light and cytokinin signaling cascades in the regulation of photomorphogenesis. Partial reversal of greening process by exogenous application of benzyladenine suggests, apart from CKs perception, transportation and responsiveness, other factors are also involved in modulation of suppression of photomorphogenesis by red light.
茎基部感知的红光通过光敏色素A介导抑制水稻幼苗的光形态建成。这些茎基部暴露在红光下生长的幼苗，其茎中叶绿素含量不足，反式玉米素核苷积累浓度高。然而，与绿色幼苗相比，在红光下生长的非绿色幼苗的茎中，异戊烯基腺苷、二氢玉米素核苷的含量降低。在这些红光下生长的非绿色幼苗中，细胞分裂素受体（OsHK5）、转运蛋白（OsENT1、OsENT2）和响应调节因子（OsRR4、OsRR10）的信使丰度下调。外源细胞分裂素类似物苄基腺嘌呤的应用，或用蓝光补充红光，可逆转绿化过程的减弱。同样，在用苄基腺嘌呤处理的红光下生长的幼苗中，细胞分裂素受体、转运蛋白和A型响应调节因子的基因表达抑制也被逆转，这表明紊乱的细胞分裂素（CK）信号级联反应是红光下生长的幼苗非绿化的原因。蓝光和苄基腺嘌呤对红光诱导的光形态建成抑制的逆转，证明了光信号和细胞分裂素信号级联反应在光形态建成调节中的相互作用。外源施用苄基腺嘌呤对绿化过程的部分逆转表明，除了CKs的感知、运输和反应外，其他因素也参与了对红光抑制光形态建成的调节。
