Mesocotyl elongation is an important trait influencing seedling emergence and establishment in rice direct-seeding cultivation and is immediately inhibited after light exposure. Detailed researches on the molecular basis and biological processes underlying light repression of mesocotyl growth could probably provide useful information for key factors controlling this trait. Here we monitored the transcriptome and endogenous phytohormone changes specifically in the elongating mesocotyl in response to light exposure with a time-course. It was revealed that 974 transcripts were significantly differentially expressed (FDR < 0.05, |log₂ (L/D) | ≥2) after light exposure. Most of the differential expression genes associated with the responses to hormone. Metabolic pathway analysis using the KEGG system suggested plant hormone signal transduction, α-linolenic acid metabolism and diterpenoid biosynthesis were critical processes of mesocotyl growth inhibited by light. Consistent with DEGs, the endogenous IAA, tZ and GA₃ content was significantly reduced while JA level was dramatically increased, which indicated that light inhibited rice mesocotyl growth through decreasing IAA, tZ and GA₃ content and/or increasing JA level. The present results enriched our knowledge about the genes and phytohormones regulating mesocotyl elongation in rice, which may help improve future studies on associated genes and develop new varieties tolerance to deep sowing.

中文翻译：

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水稻幼苗中胚轴中光照时间的动态转录组和植物激素谱。

中胚轴伸长率是影响水稻直播播种中出苗和定植的重要特征，光照后会立即受到抑制。对中胚轴生长进行光抑制的分子基础和生物学过程的详细研究可能会为控制该性状的关键因素提供有用的信息。在这里，我们监测了转录组和内源性植物激素的变化，特别是在延长的中胚轴中，随着时间的流逝而发生了光响应。揭示了974个转录本的显着差异表达（FDR <0.05，| log ₂（长/短）| ≥2）曝光后。大多数差异表达基因与对激素的反应有关。使用KEGG系统的代谢途径分析表明，植物激素信号转导，α-亚麻酸代谢和二萜类生物合成是光抑制中胚轴生长的关键过程。与DEG一致，内源IAA，tZ和GA ₃含量显着降低，而JA水平显着提高，这表明光通过降低IAA，tZ和GA ₃抑制水稻中胚轴生长。内容和/或提高JA水平。目前的结果丰富了我们对调节水稻中胚轴伸长的基因和植物激素的了解，这可能有助于改进对相关基因的未来研究，并开发出对深播的新品种耐受性。