UGT85A53 promotes flowering via mediating abscisic acid glucosylation and FLC transcription in Camellia sinensis
UGT85A53 promotes flowering via mediating abscisic acid glucosylation and FLC transcription in Camellia sinensis
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DOI：
10.1093/jxb/eraa373
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发表时间：
2020-12-31
影响因子：
6.9
通讯作者：
Song, Chuankui
中科院分区：
文献类型：
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作者：
Jing, Tingting;Zhang, Na;Song, Chuankui
尿苷二磷酸（UDP）依赖性糖基转移酶催化小分子糖基化，在维持细胞稳态和调节植物发育中起重要作用。糖基转移酶广泛分布，但其在调节植物生长发育中的具体作用在很大程度上是未知的。在本研究中，我们从茶树中鉴定了一种udp -糖基转移酶UGT85A53，该酶的表达受多种非生物胁迫因素的强烈诱导，其蛋白产物分布在细胞质和细胞核中。CsUGT85A53在拟南芥中异位过表达导致长、短日照条件下的早花表型。与野生型植物相比，转基因拟南芥开花抑制基因FLC和ABI5 （aba调控开花信号中FLC的激活因子）的转录积累量均显著降低。在csugt85a53过表达（OE）的植物中，FLC表达水平的降低可能与DNA甲基化水平的升高有关。生化分析表明，CsUGT85A53在体外和植物体内均能葡萄糖化ABA形成无活性ABA糖苷。CsUGT85A53在拟南芥中过表达导致游离ABA浓度降低，ABA-糖苷浓度升高。应用ABA恢复了CsUGT85A53-OE转基因系的早花表型。此外，CsUGT85A53-OE植株在低浓度外源ABA存在下表现出ABA不敏感表型，与对照相比萌发率更高。我们的研究结果首次在茶树中发现了一种UGT，它可以催化ABA糖基化，并作为一种积极的调节剂促进开花转变。
Uridine diphosphate (UDP)-dependent glycosyltransferases catalyse the glycosylation of small molecules and play important roles in maintaining cell homeostasis and regulating plant development. Glycosyltransferases are widely distributed, but their detailed roles in regulating plant growth and development are largely unknown. In this study, we identified a UDP-glycosyltransferase, UGT85A53, from Camellia sinensis, the expression of which was strongly induced by various abiotic stress factors and its protein product was distributed in both the cytoplasm and nucleus. Ectopic overexpression of CsUGT85A53 in Arabidopsis resulted in an early-flowering phenotype under both long- and short-day conditions. The transcript accumulation of the flowering repressor genes FLC and ABI5, an activator of FLC in ABA-regulated flowering signaling, were both significantly decreased in transgenic Arabidopsis compared with wild-type plants. The decreased expression level of FLC might be associated with an increased level of DNA methylation that was observed in CsUGT85A53-overexpressing (OE) plants. Biochemical analyses showed that CsUGT85A53 could glucosylate ABA to form inactive ABA-glycoside in vitro and in planta. Overexpression of CsUGT85A53 in Arabidopsis resulted in a decreased concentration of free ABA and increased concentration of ABA-glucoside. The early-flowering phenotype in the CsUGT85A53-OE transgenic lines was restored by ABA application. Furthermore, CsUGT85A53-OE plants displayed an ABA-insensitive phenotype with higher germination rates compared with controls in the presence of low concentrations of exogenous ABA. Our findings are the first to identify a UGT in tea plants that catalyses ABA glucosylation and enhance flowering transition as a positive regulator.