【作者】 杨明秀；

【导师】 文景芝；

【作者基本信息】 东北农业大学 ， 植物病理学， 2005， 硕士

【摘要】 在某些大豆生产区,由大豆疫霉菌引起的大豆根茎腐烂病是一种普遍流行的、极具破坏性的病害,病原真菌以卵孢子在土壤中越冬,在条件适宜时导致下一年大豆发生根茎腐烂。卵孢子通常休眠一段时间后才萌发,这阻碍了大豆疫霉菌有性生殖后代毒性的遗传和变异研究。本文测定了不同培养基、水量、农作物根渗出液、温度、光照对大豆疫霉菌卵孢子萌发影响,比较了大豆疫霉菌株间卵孢子萌发的差异,筛选出萌发率较高的菌株和适于卵孢子萌发的条什组合;通过继代单卵孢株分离培养和毒性鉴定,建立了大豆疫霉菌单卵孢株毒性纯系,并分析了单卵孢株毒性纯系后代群体ISSR分子指纹,结果如下: 1.不同培养基上卵孢子的萌发率存在很大差异,CA和S+L培养基上的卵孢子均不萌发。当平皿中存在3mL水时,卵孢子萌发率最高,为80.9%。大豆感病品种sloan的根渗出液能明显促进卵孢子的萌发,而用大豆抗病品种绥农11和小麦品种龙麦29的根渗出液处理后的卵孢子萌发率与清水对照无差异:与清水对照相比,玉米品种本育9的根渗出液对卵孢子萌发有明显的抑制作用。不同大豆疫霉菌株萌发率存在显著差异,以Ps-597-3萌发率最高,达到80.0%。26℃对卵孢子萌发最合适,萌发率高达83.5%。持续黑暗、12h光照12h黑暗交替以及连续光照3种光照处理间无明显差异,说明光照对大豆疫霉菌卵孢子萌发没有影响。 2.将大豆疫霉菌供试菌株Ps-H₂（生理小种1号）每代挑取30个单卵孢株,进行生理小种鉴定,随机挑选1株1号生理小种的单卵孢株继续进行单卵孢株分离和毒性鉴定,连续两代试验结果表明大豆疫霉菌原始菌株并朱出现毒性分化,表明原始菌株即为1号生理小种的毒性纯系。 3.用7个ISSR引物对18个1号生理小种的单卵孢株毒性纯系进行DNA指纹分析,聚类分析结果表明,ISSR在引物选用恰当的情况下,能够将参试的大豆疫霉菌1号生理小种的大多数菌株分为一类。更多还原

【Abstract】 Phytophthora root and stem rot, caused by Phytophthora sojae, is a prevalent and destructive disease in some soybean-growing regions. The causal fungus overwinters with oospores in soil and causes soybean root and stem rot next year. The oospores often remain dormant for a period of time to germinate, which comfines the research of inheritance and variation behavior of the oospores. Culture medium, water volume, root exudates of different crops, temperature, illumination affecting germination conditions of oospores of Phytophthora sojae studied in this reasch and compared the difference of germination of oospores of different race of Phytophthora sojae, filtrated the higher germination rate of strain and suitbable conditions combination of germination of oospores; The pure-line(Race 1) in virulence was obtained through isolation and culture and virulence identify of the second generation. The pure-line was analyzed by molecule method of ISSR. The results were summarized as follows:There was quite difference of germination rate of oospores on different culture medium. The oospores of Phytophthora sojae can germinated on water culture medium and did not germinated on CA and S+L culture midium. The germination rate of Phytophthora sojae reached up to 80.9% when the DDW was 3ml. Root exudates of soybean susceptible variety sloan promoted the germination of oospores in evidence. But there is no difference between root exudates of soybean resist variety Suinong 11 , corn variety Benyu 9 and water check.. Whereas there is inhibition to germination of oospores dealed with root exudates of corn variety Benyu 9. The optimum temperature is 26℃ for germination of oospores, the rate of germination reached up to 83.5%. There is no difference among treatments of persistence of dark, alternation between 12 hours dark and 12 hours illumination, continue illumination. The illumination is of no effect on the germination rate of oospores of Phytophthora sojae.30 single-oospore isolates obtained from the test strain of Phytophthora sojae Ps-H2 (Race 1 ) were evaluated using hypocotyl-inoculation method for race phenotype on soybean cultivars. One clone phenotype ( race 1 )was selected randomly for further isolation and virulence identify . The result indicatd that virulence differentiation did not happened in the original strain of Phytophthora sojae, that the original strain of Phytophthora sojae was the pure-line of in virulence of race 1after the second generation .18 pure-line of in virulence of single-oospore isolates of race 1 was carry through DNA fingerprint analysis, cluster analysis showed that most race 1 of P.sojae were the same kind by ISSR with the right primers.更多还原