Plant-Microbe Interactions Research Unit, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, 305-8602 Japan.
Plant Cell Physiol. 2012 Aug;53(8):1432-44. doi: 10.1093/pcp/pcs085. Epub 2012 Jun 7.
The soil-borne bacterial pathogen Ralstonia solanacearum invades a broad range of plants through their roots, resulting in wilting of the plant, but no effective protection against this disease has been developed. Two bacterial wilt disease-inhibiting compounds were biochemically isolated from tobacco and identified as sclareol and cis-abienol, labdane-type diterpenes. When exogenously applied to their roots, sclareol and cis-abienol inhibited wilt disease in tobacco, tomato and Arabidopsis plants without exhibiting any antibacterial activity. Microarray analysis identified many sclareol-responsive genes in Arabidopsis roots, including genes encoding or with a role in ATP-binding cassette (ABC) transporters, and biosynthesis and signaling of defense-related molecules and mitogen-activated protein kinase (MAPK) cascade components. Inhibition of wilt disease by sclareol was attenuated in Arabidopsis mutants defective in the ABC transporter AtPDR12, the MAPK MPK3, and ethylene and abscisic acid signaling pathways, and also in transgenic tobacco plants with reduced expression of NtPDR1, a tobacco homolog of AtPDR12. These results suggest that multiple host factors are involved in the inhibition of bacterial wilt disease by sclareol-related compounds.
土壤细菌病原体青枯菌通过根部侵袭广泛的植物，导致植物萎蔫，但目前尚未开发出有效的防治方法。从烟草中生化分离出两种抑制细菌枯萎病的化合物，鉴定为喇叭茶醇和顺式异贝壳杉烯醇，它们是贝壳杉烷型二萜。当外施于根部时，喇叭茶醇和顺式异贝壳杉烯醇抑制烟草、番茄和拟南芥植物的萎蔫病，而没有表现出任何抗菌活性。微阵列分析鉴定了拟南芥根部许多对喇叭茶醇有反应的基因，包括编码或参与 ABC 转运体、防御相关分子生物合成和信号转导以及丝裂原活化蛋白激酶 (MAPK) 级联成分的基因。在 ABC 转运体 AtPDR12 缺陷、MAPK MPK3 和乙烯及脱落酸信号通路缺陷的拟南芥突变体中，以及在 NtPDR1 表达降低的转基因烟草植物中，喇叭茶醇抑制萎蔫病的作用减弱，NtPDR1 是 AtPDR12 的烟草同源物。这些结果表明，多种宿主因子参与了喇叭茶醇相关化合物抑制细菌枯萎病的过程。
