恶疫霉有性杂交后代在土壤中的生长和激动孢子萌发研究

将恶疫霉突变株及其有性杂交后代的菌丝块 ( 2mm× 2mm)和游动孢子接种于灭菌土或自然土中 ,对它们的生长状况和游动孢子萌发率进行研究。结果显示 ,接种于灭菌土中的 7株杂交个体中 ,有 2株杂交个体的生长速率较快 ,其菌落半径分别为 8.0mm和 7.2mm( 3d) ,显著大于两亲本的菌落半径 (亲本AP1 4M-1 -52菌落半径为 3 .0mm ,另一亲本PK9Cn -2 -2 4生长较弱 ,不形成明显的菌落 ) ,其它杂交个体生长较弱 ,不形成明显的菌落 ;选择 3株杂交个体的游动孢子接种于灭菌土中 ,其中有两株杂交个体的游动孢子萌发率 (分别为 77.3 %和 71 .3 % )介于两亲本 (分别为 85.0 %和 67.7% )之间 ,但无显著性差异 (P =0 .0 5) ;另一杂交个体游动孢子萌发率 ( 59.7% )显著低于亲本AP1 4M -1 -52游动孢子萌发率 (P <0 .0 5)。而接种于自然土中的 7株杂交个体中 ,有 5株杂交个体长出少量菌丝和孢子囊 ,另 2株不生长 ;亲本菌株AP1 4M -1 -52有少量菌丝扩展和产生孢子囊 ,另一亲本菌株PK9Cn -2 -2 4无菌丝扩展 ;恶疫霉有性杂交个体及其亲本的游动孢子在自然中均不能萌发。结果表明恶疫霉有性杂交后代营养体和游动孢子在土壤中的生活能力与亲本相似。

A Study on the Soma Growth and Zoospore Germination of Hybrids of Phytophthora cactorum in Soil

Hyphae blocks and zoospore from hybrids and their parents of Phytophthora cactorum were inoculated in autoclaved soil and natural soil to culture for 2～3d. The result showed that, in autoclaved soil, colonial radii of two hybrids of seven tested hybrids were 8.0mm and 7.2mm (3d), respectively, larger than those of their parents (colonial radius of parental isolate AP14M－1－52 was 3.0mm, and another parental isolate PK9Cn－2－24 grew weakly and did not form obvious colony), other hybrids grew weakly and did not form obvious colonies; in natural soil, five hybrids grew very weakly, 2 hybrids did not grow. Zoospore germination rates of two hybrids of three tested hybrids were 77.3% and 71.3%, respectively, but not significantly different from those of their parents (zoospore germination rates of their parents were 85.0% and 67.7%, respectively); zoospore germination rate of one hybrid (APK－24) was significantly lower than that of its parent AP14M－1－52, but not significantly different from that of the parent PK9Cn－2－24. Of seven hybrids inoculated in natural soil, five hybrids produced mycelia and zoosporangia, two hybrids could not grow; parental isolate AP14M－1－52 produced few mycelia and zoosporangia, another parental isolate did not produce mycelia; zoospores of hybrids and their parents of Phytophthora cactorum could not germinate in natural soil. The result showed that ability of vegetation and zoospors of hybrids was the same as that of their parents.