Department of Forest Resources, College of Forest and Environmental Sciences, Kangwon National University, Chuncheon 200-701, Republic of Korea.
Tree Physiol. 2021 Oct 4;41(10):1972-1987. doi: 10.1093/treephys/tpab053.
Pine wood nematodes (PWNs; Bursaphelenchus xylophilus) infect pine trees and cause serious pine wilt disease. Eastern white pine (Pinus strobus) has resistance to PWN. However, the detailed defense mechanisms of P. strobus against PWN are not well known. When P. strobus plants were infected with PWNs, the accumulation of stilbenoids, dihydropinosylvin monomethyl ether (DPME) and pinosylvin monomethyl ether (PME) was increased remarkably. Both DPME and PME had high nematicidal activity. The nematicidal activity of the two compounds was resulted in a developmental stage-dependent manner. Pinosylvin monomethyl ether was more toxic to adult PWNs than juveniles, whereas DPME was found more toxic to juvenile PWNs than the adults. The genes involved in PME and DPME biosynthesis such as phenylalanine ammonia-lyase (PAL), 4-coumarate-CoA ligase (4CL), pinosylvin synthase (STS) and pinosylvin O-methyltransferase (PMT) were isolated using de novo sequencing of the transcriptome in P. strobus. In addition, transcription factors (TFs; bHLH, MYB and WRKY) related to stilbene biosynthesis were isolated. qPCR analyses of the selected genes (PAL, 4CL, STS and PMT) including TFs (bHLH, MYB and WRKY) revealed that the expression level of the selected genes highly enhanced after PWN infection. Our results suggest that pinosylvin-type stilbenoid biosynthesis is highly responsive to PWN infection and plays an important role in PWN resistance of P. strobus trees.
松材线虫（Bursaphelenchus xylophilus）感染松树并引起严重的松萎病。东方白松（Pinus strobus）对松材线虫具有抗性。然而，东方白松抵御松材线虫的详细防御机制尚不清楚。当东方白松植株感染松材线虫时，芪类物质、二氢松柏醇甲醚（DPME）和松柏醇甲醚（PME）的积累显著增加。DPME 和 PME 均具有很高的杀线虫活性。两种化合物的杀线虫活性呈发育阶段依赖性。松柏醇甲醚对成虫松材线虫的毒性大于幼体，而 DPME 对幼体松材线虫的毒性大于成虫。使用东方白松转录组从头测序分离了与 PME 和 DPME 生物合成相关的基因，如苯丙氨酸解氨酶（PAL）、4-香豆酸辅酶 A 连接酶（4CL）、松柏醇合酶（STS）和松柏醇 O-甲基转移酶（PMT）。此外，还分离了与芪类生物合成相关的转录因子（TF；bHLH、MYB 和 WRKY）。对选定基因（PAL、4CL、STS 和 PMT）包括 TF（bHLH、MYB 和 WRKY）的 qPCR 分析表明，选定基因的表达水平在 PWN 感染后显著增强。我们的结果表明，松柏醇型芪类物质生物合成对 PWN 感染高度敏感，在东方白松抵御 PWN 方面发挥重要作用。
