植物激素水杨酸(SA)在植物先天免疫中起着至关重要的作用。确定了几种SA衍生物和相关的修饰,而SA相关代谢物的范围和作用方式仍然难以捉摸。这里,该研究发现2,4-二羟基苯甲酸(2,4-DHBA)及其糖基化形式在植物中作为天然SA衍生物,其积累主要由SA施用和Ps诱导。山茶花(Pcs)感染。CsSH1,一种4/5-羟化酶,催化SA羟化为2,4-DHBA,UDP-葡萄糖基转移酶UGT95B17催化2,4-DHBA葡糖苷的形成。下调降低了2,4-DHBA葡糖苷的积累,并增强了茶树对Pcs的敏感性。相反,UGT95B17的过表达增加了植物的抗病性。2,4-DHBA和2,5-DHBA的外源施用,以及DHBA的积累和植物抗性的比较,表明2,4-DHBA作为潜在的生物活性分子起作用,并且主要作为葡萄糖缀合物在茶树中储存,与拟南芥中描述的机制不同。当2,4-DHBA外源施用时,UGT95B17沉默的茶树比SA积累更多的2,4-DHBA,并显示出对Pcs感染的诱导抗性。这些结果表明,2,4-DHBA糖基化正调节抗病性,并突出了2,4-DHBA作为潜在生物活性分子在茶树基础抗性建立中的作用。
The plant hormone salicylic acid (SA) plays critical roles in plant innate immunity. Several SA derivatives and associated modification are identified, whereas the range and modes of action of SA-related metabolites remain elusive. Here, the study discovered 2,4-dihydroxybenzoic acid (2,4-DHBA) and its glycosylated form as native SA derivatives in plants whose accumulation is largely induced by SA application and Ps. camelliae-sinensis (Pcs) infection. CsSH1, a 4/5-hydroxylase, catalyzes the hydroxylation of SA to 2,4-DHBA, and UDP-glucosyltransferase UGT95B17 catalyzes the formation of 2,4-DHBA glucoside. Down-regulation reduced the accumulation of 2,4-DHBA glucosides and enhanced the sensitivity of tea plants to Pcs. Conversely, overexpression of UGT95B17 increased plant disease resistance. The exogenous application of 2,4-DHBA and 2,5-DHBA, as well as the accumulation of DHBA and plant resistance comparison, indicate that 2,4-DHBA functions as a potentially bioactive molecule and is stored mainly as a glucose conjugate in tea plants, differs from the mechanism described in Arabidopsis. When 2,4-DHBA is applied exogenously, UGT95B17-silenced tea plants accumulated more 2,4-DHBA than SA and showed induced resistance to Pcs infection. These results indicate that 2,4-DHBA glucosylation positively regulates disease resistance and highlight the role of 2,4-DHBA as potentially bioactive molecule in the establishment of basal resistance in tea plants.