Arabidopsis SAURs Are Critical for Differential Light Regulation of the Development of Various Organs. Arabidopsis thaliana

During de-etiolation 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 PP2C-Ds. Light reduced auxin levels to down-regulate the expression of lirSAURs in hypocotyls. Further, phytochrome-interacting factors (PIFs) were shown Overall design: Totally eighteen wild type samples, three treatments and two organs, and each has three replicates. Totally six pifq samples, two organs, and each has three replicates.

在拟南芥幼苗的去黄化（de-etiolation）过程中，光信号可促进子叶扩展，但抑制下胚轴伸长，目前这种细胞增大的差异化调控机制仍不明确。本研究通过器官特异性转录组分析，鉴定出32个生长素上调小RNA（Small Auxin Up RNA, SAUR）基因，其转录本在子叶中受光诱导，或在下胚轴中受光抑制，因此将此类SAUR基因命名为光响应SAUR（lirSAURs）。过表达与基因突变分析均证实，lirSAURs能够促进子叶扩展与开张，并增强下胚轴伸长，其潜在调控机制可能为抑制PP2C-D家族蛋白磷酸酶的活性。光信号可通过降低生长素水平，下调下胚轴中lirSAURs的表达。进一步研究表明，光敏色素互作因子（phytochrome-interacting factors, PIFs）。整体实验设计如下：共包含18份野生型样本，涵盖3种处理、2种器官，每组均设置3次生物学重复；另包含6份pifq样本，涵盖2种器官，每组均设置3次生物学重复。