Arabidopsis SAURs are critical for differential light regulation of the development of various organs
Arabidopsis SAURs are critical for differential light regulation of the development of various organs
复制标题
拟南芥 SAUR 对于各种器官发育的差异光调节至关重要
DOI：
10.1073/pnas.1604782113
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发表时间：
2016-05-24
影响因子：
11.1
通讯作者：
Chen, Haodong
中科院分区：
文献类型：
--
作者：
Sun, Ning;Wang, Jiajun;Chen, Haodong
Significance Various plant organs respond differentially to environmental signals so that plants can adapt to dynamic environments without movement. Light is a key environmental factor mediating multiple plant developmental processes. For example, it induces cotyledon expansion but inhibits hypocotyl elongation when plants emerge from soil. Although this opposite regulation is crucial for plant survival and has been described for decades, the underlying mechanism is still elusive. In this study, we demonstrated that temporal–spatial expression of a group of Small Auxin Up RNAs (SAURs) is regulated by light through auxin and phytochrome-interacting factors, and these SAURs further mediate the differential growth of cotyledons and hypocotyls. Thus, this study provides a molecular mechanism explaining how light differentially regulates the growth of various plant organs. During deetiolation of Arabidopsis seedlings, light promotes the expansion of cotyledons but inhibits the elongation of hypocotyls. The mechanism of this differential regulation of cell enlargement is unclear. Our organ-specific transcriptomic analysis identified 32 Small Auxin Up RNA (SAUR) genes whose transcripts were light-induced in cotyledons and/or repressed in hypocotyls. We therefore named these SAURs as lirSAURs. Both overexpression and mutation analyses demonstrated that lirSAURs could promote cotyledon expansion and opening and enhance hypocotyl elongation, possibly by inhibiting phosphatase activity of D-clade type 2C protein phosphatases (PP2C-Ds). Light reduced auxin levels to down-regulate the expression of lirSAURs in hypocotyls. Further, phytochrome-interacting factors (PIFs) were shown to directly bind the genes encoding these SAURs and differentially regulate their expression in cotyledons and hypocotyls. Together, our study demonstrates that light mediates auxin levels and PIF stability to differentially regulate the expression of lirSAURs in cotyledons and hypocotyls, and these lirSAURs further mediate the differential growth of these two organs.
