草酸青霉菌果胶酶诱导黄瓜抗黑星病研究

Induced resistance to Cladosporium cucumerinum in cucumber by pectinases extract of Peni- cillium oxalicum

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(Cladosporiumcucumerinum)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。

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.