相同立地条件下向日葵核盘菌、小核盘菌生物学特性及致病力的比较

Comparison on the biological characteristics and pathogenicity between Sclerotinia sclerotiorum and Sclerotinia minor from the same sunflower field

以同一地块中采集的向日葵核盘菌和小核盘菌各10株菌株作为供试材料,对其生物学特性及致病力进行了比较研究。结果表明:23℃培养3 d后,核盘菌平均直径达到8.34 cm,而小核盘菌的平均直径仅为5.38 cm。草酸含量和PG酶活力的测定结果表明:核盘菌草酸含量的平均值为27.67μg/mg,PG酶活力平均值为26.87 U/mg,而小核盘菌上述两个指标的平均值分别为18.91μg/mg和21.58 U/mg。在菌核形成方面,小核盘菌不仅菌核形成速度明显快于核盘菌,而且其形成菌核颗粒的数量明显多于核盘菌。致病力的测定结果表明:接种2 d后,核盘菌在向日葵离体叶片上形成病斑的平均直径为3.11 cm,在0.05水平上显著高于接种相同时间点小核盘菌形成的病斑直径的平均值1.71 cm。因此,除了菌核的形成时间和数量外,同一地块中向日葵核盘菌菌株生物学特性各项指标以及致病力均高于小核盘菌菌株。

In this study, twenty isolates were randomly chosen from the population of Sclerotinia sclerotiorum（S. sclerotiorum）（n=10） and Sclerotinia minor（S. minor）（n=10）. They were collected from the same sunflower field in Inner Mongolia region and compared for the difference in biological characteristics and pathogenicity. Our data indicated that after incubation on PDA at 23 ℃ for 3 days, the average diameters of S. sclerotiorum and S. minor colonies were 8.3 cm and 5.3 cm, respectively. The average yield of oxalic acid（OA） and polygalactourase（PG） activity of S. sclerotiorum isolates were 27.67 μg/mg mycelia and26.87 U/mg mycelia, respectively; for S. minor, those were 18.91 μg/mg mycelia and 21.58 U/mg mycelia, respectively. The sclerotial initiation and number of sclerotial of S. minor were much earlier and higher than that of S. sclerotiorum. The pathogenicity was also compared by using detached leaf assay. Our results indicated that the average lesion size at 2 days post inoculation of S. sclerotiorum was 3.11 cm which was significantly larger than that of S. minor（1.71 cm） at 0.05 significance level. In conclusion, except for the sclerotial formation, the S. sclerotiorum isolates showed higher growth speed,PG enzymes activity and pathogenicity compared with S. minor collected from the same sunflower field.