Instituto de Biología Molecular y Celular de Plantas, Ciudad Politécnica de la Innovación, Ingeniero Fausto Elio s/n, Valencia, Spain.
Plant Cell Environ. 2010 Jan;33(1):11-22. doi: 10.1111/j.1365-3040.2009.02045.x. Epub 2009 Sep 23.
Salicylic acid (SA) has been characterized as an activator of pathogen-triggered resistance of plants. SA also regulates developmental processes such as thermogenesis in floral organs and stress-induced flowering. To deepen our knowledge of the mechanism underlying SA regulation of flowering time in Arabidopsis, we compared the transcriptomes of SA-deficient late flowering genotypes with wild-type plants. Down- or up-regulated genes in SA-deficient plants were screened for responsiveness to ultraviolet (UV)-C light, which accelerates flowering in Arabidopsis. Among them, only Pathogen and Circadian Controlled 1 (PCC1) was up-regulated by UV-C light through a SA-dependent process. Moreover, UV-C light-activated expression of PCC1 was also dependent on the flowering activator CONSTANS (CO). PCC1 gene has a circadian-regulated developmental pattern of expression with low transcript levels after germination that increased abruptly by day 10. RNAi plants with very low expression of PCC1 gene were late flowering, defective in UV-C light acceleration of flowering and contained FLOWERING LOCUS T (FT) transcript levels below 5% of that detected in wild-type plants. Although PCC1 seems to function between CO and FT in the photoperiod-dependent flowering pathway, transgenic plants overexpressing a Glucocorticoid Receptor (GR)-fused version of CO strongly activated FT but not PCC1 after dexamethasone treatment.
水杨酸（SA）被认为是植物病原体触发抗性的激活剂。SA 还调节发育过程，如花器官的热生成和应激诱导开花。为了深入了解 SA 调控拟南芥开花时间的机制，我们比较了 SA 缺乏的晚花基因型与野生型植物的转录组。筛选了 SA 缺乏植物中下调或上调的基因对紫外线（UV）-C 光的反应性，UV-C 光可加速拟南芥开花。其中，只有通过依赖 SA 的过程，UV-C 光才上调病原体和昼夜节律控制 1（PCC1）。此外，UV-C 光激活 PCC1 的表达也依赖于开花激活因子 CONSTANS（CO）。PCC1 基因的表达具有昼夜节律调节的发育模式，在萌发后转录本水平较低，在第 10 天突然增加。PCC1 基因表达水平非常低的 RNAi 植物开花晚，UV-C 光加速开花的能力受损，并且 FT 转录本水平低于野生型植物的 5%。尽管 PCC1 似乎在光周期依赖的开花途径中 CO 和 FT 之间发挥作用，但过表达 Glucocorticoid Receptor（GR）融合 CO 的转基因植物在经过地塞米松处理后强烈激活 FT，但不激活 PCC1。
