【作者】 李涛；

【导师】 王克荣；

【作者基本信息】 南京农业大学 ， 植物病理学， 2008， 硕士

【摘要】 栗疫病(Chestnut blight)是栗属(Castanea)植物上最常见、最重要的病害,也是世界著名的森林病害之一。本文对栗疫病菌的群体结构进行了研究。本文对栗疫菌(Cryphonectria parasitica)的交配型的分子测定和杂交进行了研究。结果表明,测定16个菌株其中8个菌株是MAT-1,另外8个菌株为MAT-2;杂交共获得6种新基因型菌株,每种基因型菌株通过1种杂交组合或者2种杂交组合所获得,前者杂交结果具有相同的遗传背景,后者结果具有不同的遗传背景。新基因型菌株的获得对研究弱毒性病毒的水平传递具有重要意义。对栗疫病菌(Cryphonectria parasitica)菌株间单个营养体不亲和性(vegetativeincompatibility,vic)基因差异对弱毒性病毒传递的影响进行了研究。将含病毒菌株与具单个vic基因座位差异的野生型菌株配对培养,10天后调查菌株间的病毒传递率。结果表明,相同vic基因型菌株间的病毒传递率为100%;在1个vic座位上的基因不同通常会降低病毒的传递率,在vic-C基因座位上有差异的菌株间的病毒平均传递率为87.00%,而在vic-D座位上的基因不同,菌株间病毒的平均传递率仅为8.79%,在vic-A、vic-B座位上基因不同的菌株间病毒平均传递率分别为44.12%、48.93%。vic-B座位上基因不同的菌株间的病毒正反向传递率相差非常大,由vic-b菌株向vic-B菌株的平均病毒传递率为83.13%,而从vic-B菌株向vic-b菌株的平均病毒传递率只有23.15%;其他3个vic基因不同的菌株间的病毒传递率也具有不明显的方向性。对栗疫病菌(Cryphonectria parasitica)菌株间营养体不亲和性(vegetaiveincompatibility,vic)基因差异对弱毒性病毒传递的影响进行了研究。把供体菌株与受体菌株配对培养,10天后调查菌株间的病毒传递率。结果表明,栗疫病菌的营养体不亲和是弱毒性病毒传递的重要障碍,但不是绝对障碍;相同vic基因型菌株间的病毒传递率为100%,相差1-4个vic基因,病毒的传递率分别为44.31%、26.92%、6.85%、0.59%;相差1个vic基因病毒的传递率有很大的变化,传递率从88.46%下降到9.01%;具有相同的vic基因差异且病毒传递方向一致,配对菌株间的弱毒性病毒传递有一定的方向性。通过回归模型,相差2个vic基因6菌株间配对有4对是显著上位效应,相差3个vic位点菌株间配对没有上位效应。说明不同vic位点、非对称性、上位效应对病毒传递有显著影响,但是寄主的遗传背景、供体菌和受体菌的具体基因型对病毒传递也存在显著影响。说明单独的vic基因并不能完全解释病毒传递的变化。对利用弱毒力菌株防治栗疫病(病原:Cryphonectria parasitica)进行了研究。把弱毒力菌株通过不同的方法接种,每年秋天调查病毒的传递率、田间病毒的动态检测及防治效果。结果表明,湖山乡试验田的36个菌株中有33个VCGS(vegetativecompatibility group,VCG),平均1个VCG只有1.09个菌株,具有同一VCG的菌株都是来自同一小区。在大柘镇的试验田中,营养体亲和群也比较复杂,平均1个VCG最多含有1.25个菌株。4个(vegetative incompatibility,vic)位点差异的菌株间配对在田间接种半年后,弱毒性病毒发生传递率为0。处理病斑半年后仅有两个小区病毒发生传递且发生传递的病毒都为280,分别为15%、10%。说明了含有280的弱毒力菌株在田间更容易传播。接种1年半后,病毒在田间没有发生传播。更多还原

【Abstract】 Chestnut blight epidemic is associated with devastation of Castanea,Chestnut blight also one of an important disease in the forests.The population diversity of Cryphonectria parasitica was studied in this thesis.Molecular detection of mating type and crossing were tested in Cryphonectria parasitica.The results show that eight strains were MAT-1 in tested sixteen strains and others were MAT-2. Six kinds of isolates of new genotype were obtained through one or two sexsual crossing group between isolates which have known genotypes.The former crossing results had the same genetic background and the latter crossing results had different genetic background. Obtained new genotype isolates was important to study horizontal virus transmission.Effect of heteroallelism at each vic locus on transmission of hypovirus in Cryphonectria parasitica was characterized.The 16 isolates of different genotype at 4 vegetative incompatibility(vic) loci were obtained through sexsual crossing between isolates which have known genotypes.Virus transmission was assayed by growing donor and recipient isolates together.Virus transmission occured with 100%frequency when donor and recipient isolates had the same vic genotypes but heteroallelism at one of these loci generally reduced virus transmission.Transmission occurred in 87.00%of pairings that were heteroallelic at vic-C while only in 8.79%of pairings that were heteroallelic at vic-D. The average vires transmission rates were 44.12%and 48.93%respectively when vic-A and vic-B were heteroallelic.Virus transmission was asymmetric,at the extremes,pairs that were heteroallelic at vic-B showed strong asymmetry:transmission rate was 83.13%when virus transfer from vic-b isolate to vic-B but occurred only 23.15%when virus transfer from vic-B isolate to vic-b,and in other vic loci this asymmetry were also observed though not significantly.Effect of different vic genes on transmission of hypovirus in Cryphonectria parasitica was characterized in this report.After ten days,virus transmission was assayed by growing donor and recipient isolates together.The results showed that vegetative incompatibility in Cryphonectria parasitica has reduced the transmission of viruses between individuals,but the barrier to transmission is incomplete.Virus transmission occured with 100%frequency when donor and recipient isolates had the same vic genotype.Frequencies of transmission were 44.31%,26.92%,6.85%and 0.59%with different genes from one to four,and were decreased from 88.46 to 9.01%at one difference of four loci.Virus transmission had directed in the pairing of isolates which had difference of the same vic genes and the same transmission direction.Through logistic regression model,four groups of isolates of heteroallelism at two vic loci had statistically significant interactions(epistasis),but effects of heteroallelism at three vic loci were not epistasis.This test showed that Heteroallelism at vic loci,asymmetry,and epistasis were the dominant factors controlling transmission,but host genetic background and genotype of donor and recipient isolates also were statistically signiticant effects,indicating that vic genes alone cannot explain all the variations in virus transmission.This report gives a survey on biological control of chestnut blight with hypovirulence. Hypovirulent isolates were inoculated with different methods,and the investigations were done in every autumn for the virus transmission rate,virus dynamic detection in the field and the control effect.The results show that experimental field of 36 strains were divided into 33 VCGs in Hushan town,every VCG only had 1.09 strain and strains of the same VCG were from the same district.In the experimental field of Dazhe town,VCGs were more complex and every VCG had no more than 1.25 strains on average.Heteroallelism at four vic loci between the pairings in the fields six months after the inoculation,did not happen hypovirus transmission.Half a year after dealing with canks,only two districts had virus transmission and occurred as 280,the rate was 15%and 10%respectively.It means that the strains containing virus 280 were more easily spread in the fields.One and a half years after the inoculation,the virus did not transmit in the fields.更多还原