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通过离体子叶冷冻法、离体叶片冷冻法和10%二甲基亚砜+5%脱脂乳冷冻法等3种方法来保藏大白菜霜霉病菌寄生霜霉,并采用离体子叶接种法测定孢子囊的致病力,以筛选出一种较好的保藏方法。结果表明,保藏6个月后,离体子叶冷冻法和离体叶片冷冻法保藏的孢子囊的萌发率、发病率和病情指数均较高;而10%二甲基亚砜+5%脱脂乳冷冻法保藏6个月后仅有2.16%的孢子囊能够萌发,菌株致病力丧失,发病率和病情指数均为0。保藏12个月后,离体子叶冷冻法保藏效果最好,孢子囊萌发率达到62.22%,发病率为90%,病情指数为48.89;离体叶片冷冻法保藏的孢子囊的致病力较弱;10%二甲基亚砜+5%脱脂乳冷冻法保藏12个月的孢子囊全部失活。此外,采用离体子叶冷冻法保藏12个月的32株寄生霜霉复壮成功率达到了93.75%。离体子叶冷冻法适用于寄生霜霉的保藏,其孢子囊可长时间保持较高的萌发率。
Parasitism of the Chinese cabbage downy mildew was deposited by in vitro cotyledon freezing, detached leaf freezing and 10% dimethyl sulfoxide + 5% skim milk freezing, and the in vitro cotyledon inoculation method was used to determine Sporangia virulence to filter out a better method of preservation. The results showed that the germination rate, morbidity and disease index of sporangia stored in vitro cotyledon freezing and in vitro leaf freezing were all higher after 6 months of storage, while 10% dimethyl sulfoxide + 5% skim milk After 6 months of cryopreservation, only 2.16% of the sporangia germinated and the pathogenicity of the strain was lost. The incidence and disease index were both 0. After 12 months of storage, the cotyledon cryopreservation method was the best, the germination rate of sporocysts reached 62.22%, the incidence rate was 90% and the disease index was 48.89. The pathogenicity of the sporangia preserved by the detached leaf freezing method was weak ; 10% dimethyl sulfoxide + 5% skim milk frozen 12-month sporozoites were all inactivated. In addition, the survival rate of 32 parasitized offspring recovered with 12 months’ in vitro cotyledon freezing method reached 93.75%. In vitro cotyledon freezing method is suitable for the preservation of parasitic downy mildew, the sporocysts can maintain a high germination rate for a long time.