大白菜霜霉病菌寄生霜霉孢子囊的保藏方法

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。

The preservation methods for sporangia of Chinese cabbage downy mildew pathogen Peronospora parasitica

Three methods (cotyledon in vitro refrigeration, leaf in vitro refrigeration and 10% dimethyl sulfoxide plus 5% skimmed milk refrigeration) were used to preserve sporangia of Peronospora parasitica, the pathogen of Chinese cabbage downy mildew. Cotyledon in vitro inoculation method was adopted to measure the pathogenicity of sporangia of P. parasitica for screening a better preservation method. The experimental results indicated that the sporangia preserved in 6 months by use of cotyledon in vitro refrigeration method and leaf in vitro refrigeration method had higher germination rate, incidence and disease index, on the contrary, when the sporangia were preserved by use of 10% dimethy sulfoxide plus 5% skimmed milk refrigeration method, germination rate, incidence and disease index have decreased to 2.16%, 0 and 0 respectively. Cotyledon in vitro refrigeration method showed best preservation effect. After being preserved for 12 months, germination rate, incidence and disease index of the pathogen were 62.22%, 90% and 48.89 respectively. The sporangia preserved by use of leaf in vitro refrigeration method showed weak pathogenicity, and the sporangia lost their vitality when they were preserved by use of 10% dimethy sulfoxide plus 5% skimmed milk refrigeration method. Thirty-two isolates of the pathogen were successfully rejuvenated by 93.75% when they were preserved by use of cotyledon in vitro refrigeration method in 12 months. It is concluded that cotyledon in vitro refrigeration is a good method for long period preservation of P. parasitica with higher germination rate.