无菌松材线虫对华北落叶松、油松和马尾松的致病性

Pathogenicity of Aseptic Bursaphelenchus xylophilus on Larix principis-rupprechtii,Pinus tabuliformis and Pinus massoniana

为了探讨松材线虫在松材线虫病中的作用,采用质量分数30%H_(2)O_(2)对华北落叶松、油松和马尾松的成熟种子进行灭菌处理,获得无菌实生苗;于无菌条件下,采用截顶法对4月龄无菌苗进行无菌松材线虫(500条/株)接种,观察松苗萎蔫情况,并于接种25 d后对植株取样进行线虫再分离,统计不同植株体内的线虫种群数量。结果表明:30%H_(2)O_(2)处理20 min,华北落叶松、油松和马尾松成熟种子无菌萌发率平均分别为60.1%、47.5%和67.7%。无菌松材线虫接种可导致3种无菌松苗发病,其症状与松材线虫病野外症状相似;接种25 d后,华北落叶松、油松和马尾松苗的萎蔫率分别为53.3%、78.3%和89.2%,对照植株无任何发病症状。线虫再分离结果表明:3个松种萎蔫植株体内均能再分离到松材线虫,马尾松和油松苗体内松材线虫数量高于华北落叶松,马尾松、油松和华北落叶松植株内再分离线虫数量分别为(2 628±3 322)、(2 627±2 287)和(1 144±608)条/株,经LB液体培养基检验,再分离线虫中未发现有任何细菌生长。无菌化处理未使松材线虫丧失其对3种松苗的致病性,松材线虫为引起松苗萎蔫的直接因素。

To explore the roles of Bursaphelenchus xylophilus(pine wood nematode,PWN) in pine wilt disease(PWD),the matured seeds of L.principis-rupprechtii,P.tabuliformis and P.massoniana were treated with 30% H_(2)O_(2),and aseptic seedlings were obtained.Under aseptic conditions,4-month-old healthy aseptic seedlings were artificially inoculated with aseptic PWNs(500 nematodes/plant) using the top-truncated method,followed by observation of seedling wilting.The PWNs were recovered from wilting seedlings for 25 d after inoculation and the nematode populations in different plants were counted.The aseptic germination rate of seeds of L.principis-rupprechtii,P.tabuliformis and P.massoniana were 60.1%,47.5% and 67.7%,respectively.Aseptic PWNs wilted 4-month-old seedlings of L.principis-rupprechtii,P.tabuliformis and P.massoniana,which showed similar symptom.The 53.3%,78.3% and 89.2% of seedlings of L.principis-rupprechtii,P.tabuliformis and P.massoniana were wilted for 25 d after inoculation,while all seedlings in control group remained healthy.The PWNs were recovered from wilted seedlings.The average number of nematodes was 2 628±3 322 ind./seedling(4 00-9 267),2 627±2 287 ind./seedling(133-6 800) and 1 144±608 ind./seedling(433-1 900),respectively.Asepsis did not make PWNs lose their pathogenicity on three species of pine seedlings.PWN is the direct cause of pine wilting.