Research Core for Interdisciplinary Sciences, Okayama University, Okayama, Japan.
Plant Signal Behav. 2012 Dec;7(12):1715-7. doi: 10.4161/psb.22368. Epub 2012 Oct 16.
Plant activators are agrochemicals that protect plants from a broad range of pathogens by activating the plant immune system. Unlike pesticides, they do not target pathogens; therefore, plant activators provide durable effects that are not overcome by pathogenic microbes. Although certain plant activators have been applied to paddy fields for more than 30 years, the molecular basis of the underlying immune induction are unclear. From the screening of 10,000 diverse chemicals by a high-throughput screening procedure to identify compounds that specifically enhance pathogen-induced cell death in Arabidopsis cultured cells, we identified 7 compounds, which we designated as immune priming chemicals (Imprimatins). These compounds increased disease resistance against pathogenic Pseudomonas bacteria in Arabidopsis plants. Pretreatments increased the accumulation of endogenous salicylic acid (SA) but reduced its metabolite, SA-O-β-D-glucoside (SAG). Imprimatins inhibited the enzymatic activities of 2 SA glucosyltransferases (SAGTs) in vitro at concentrations effective for immune priming. Single and double knockout Arabidopsis plants for both SAGTs consistently exhibited enhanced disease resistance and SA accumulation. Our results demonstrate that the control of the free SA pool through SA-inactivating enzymes can be a useful methodology to confer disease resistance in plants. SAGTs can pave the way for target-based discovery of novel crop protectants.
植物激活剂是通过激活植物免疫系统来保护植物免受多种病原体侵害的农用化学品。与杀虫剂不同，它们不是针对病原体的；因此，植物激活剂提供持久的效果，不会被病原微生物克服。尽管某些植物激活剂已经在稻田中使用了 30 多年，但潜在免疫诱导的分子基础尚不清楚。我们通过高通量筛选程序筛选了 10000 种不同的化学物质，以鉴定专门增强拟南芥培养细胞中病原体诱导细胞死亡的化合物，我们鉴定出了 7 种化合物，将其命名为免疫启动化学物质（Imprimatins）。这些化合物提高了拟南芥植物对致病假单胞菌的抗病性。预处理增加了内源性水杨酸（SA）的积累，但降低了其代谢物 SA-O-β-D-葡萄糖苷（SAG）的含量。Imprimatins 在有效免疫启动的浓度下，体外抑制了 2 种 SA 葡糖苷酶（SAGTs）的酶活性。SAGTs 的单敲除和双敲除拟南芥植物均表现出增强的抗病性和 SA 积累。我们的结果表明，通过 SA 失活酶控制游离 SA 池可以成为赋予植物抗病性的一种有用方法。SAGTs 可以为基于靶标的新型作物保护剂的发现铺平道路。
