草酸青霉菌果胶酶诱导黄瓜抗黑星病研究

 本文就草酸青霉菌(Penicillium oxalicum)的固态发酵提取产物--果胶酶粗酶液诱导黄瓜对黑星病(Cladosporium cucumerinum)的抗性进行了研究。以果胶酶粗酶液喷雾处理4个感黑星病黄瓜品种的黄化苗,48 h后挑战接种黑星病菌孢子悬液,其中"中农5号"黄瓜品种表现的诱导抗病效果最好,诱抗效果达62.51%。不同浓度果胶酶诱导处理黄瓜,发现果胶酶浓度在20 U/mL时,可导致黄瓜发病略高于对照;在40~200 U/mL浓度范围内,诱导效果较为明显。通过研究果胶酶诱导抗病的时效性,表明诱导处理前接种病菌或诱导处理后0、6 h接种的各处理病情指数与对照间没有差别,而诱导处理12~72 h后接种病菌的,果胶酶的诱导抗病效果均很明显,诱抗效果达29.64%~60.02%。实验还表明,随着挑战接种压力的增大,果胶酶的诱导抗病效果降低。果胶酶不能抑制黑星病菌孢子萌发,相反可以促进孢子萌发和芽管生长。

Induced resistance to Cladosporium cucumerinum in cucumber by pectinases extract of Penicillium oxalicum

The induced resistance to C. cucumerinum in etiolated cucumber seedlings was elicited by crude pectinases extract (PE) from the solid-state fermentation with P. oxalicum BZ-2002. Etiolated cucumber seedlings of 4 susceptible cultivars inoculated with C. cucumerinum at 48 h after spraying treatment with PE exhibited different degrees of increased resistance to the disease. Cucumber seedlings of cv. Zhongnong No. 5 expressed the highest resistance with inducing efficiency of 62. 51%. Different concentrations ranging from 20 to 300 U/mL of crude PE were tested for their effect on induced resistance to cucumber scab. The results indicated that the plants treated with PE at the concentration of 20 U/mL resulted in a little higher disease index than control plants, induced resistance of the plants was enhanced at the PE concentrations between 40 U/mL and 200 U/mL. Spraying cucumber seedlings with PE 12-72 h before inoculation provided significant control of the disease compared with control and the reduction rates of disease index were 29. 64%-60. 02 %. No protection was observed in seedlings treated with PE 0-6 h before inoculation or 0-48 h after inoculation. With the increase of inoculum, the efficiency of induced resistance caused by PE was reduced. No inhibitory activity was observed on conidial germination and germ-tube growth of C. cucumerinum at various concentrations of PE (20-200 U/mL). On the contrary, they had stimulative effect on conidial germination and germ-tube growth.