ABSTRACT

Plant response to light is a complex and diverse phenomenon. Several studies have elucidated the mechanisms via which light and hormones regulate hypocotyl growth. However, the hormone-dependent ultraviolet-B (UV-B) response in plants remains obscure. Involvement of gibberellins (GAs) in UV-B-induced hypocotyl inhibition and its mechanisms in Arabidopsis thaliana were investigated in the present research. UV-B exposure remarkably decreased the endogenous GA₃ content through the UV RESISTANCE LOCUS 8 (UVR8) receptor pathway, and exogenous GA₃ partially restored the hypocotyl growth. UV-B irradiation affected the expression levels of GA metabolism-related genes (GA20ox1, GA2ox1 and GA3ox1) in the hy5-215 mutant, resulting in increased GA content.ELONGATED HYPOCOTYL 5 (HY5) promoted the accumulation of DELLA proteins under UV-B radiation; HY5 appeared to regulate the abundance of DELLAs at the transcriptional level under UV-B. As a result, the GA₃ content decreased, which eventually led to the shortening of the hypocotyl. To conclude, the present study provides new insight into the regulation of plant photomorphogenesis under UV-B.

摘要

植物对光的反应是一种复杂而多样的现象。几项研究已经阐明了光和激素调节下胚轴生长的机制。然而，植物中依赖于激素的紫外线-B (UV-B) 反应仍然不清楚。本研究研究了赤霉素 (GAs) 在 UV-B 诱导的拟南芥下胚轴抑制中的作用及其机制。UV-B 暴露通过UV RESISTANCE LOCUS 8 (UVR8) 受体途径显着降低了内源性GA _{3含量，并且外源性GA 3}部分恢复了下胚轴生长。UV-B 照射影响 GA 代谢相关基因 ( GA20ox1、GA2ox1和GA3ox1 ) 的表达水平) 在hy5-215突变体中，导致 GA 含量增加。 ELONGATED HYPOCOTYL 5 (HY5) 在 UV-B 辐射下促进 DELLA 蛋白的积累；HY5 似乎在 UV-B 下在转录水平上调节 DELLA 的丰度。结果，GA ₃含量降低，最终导致下胚轴缩短。总之，本研究为 UV-B 下植物光形态发生的调控提供了新的见解。