线虫共生菌对水稻纹枯病和稻瘟病的抑菌活性

Inhibitory Activity of Xenorhabdus spp. Against Rhizoctonia solani and Pyricularia grisea

用菌块移植法初步测定了38株昆虫病原线虫共生细菌对水稻纹枯病菌和稻瘟病菌的抑菌活性,从中选出9株对纹枯病菌,7株对稻瘟病菌有较强抑菌作用的菌株,再用稀释平板法分别测定了这2组菌株的发酵液对纹枯病菌和稻瘟病菌菌丝生长、菌核或分生孢子萌发的抑制活性,筛选出对纹枯病菌和稻瘟病菌都有较强抑菌活性的YNa111和YNd173等菌株。YNa111菌株的发酵液对纹枯病菌的生长有强烈的抑菌活性,稀释40倍的发酵液24h的抑菌率为100%,160倍时为82%。菌株YNd173的发酵液对稻瘟病菌的生长有较强的抑菌活性,稀释5倍和10倍时的抑制率分别为88%和76%。

Inhibitory activity of the by-products of thirty eight strains of Xenorhabdus, the symbiotic bacteria of entomopathogenic nematodes, against the rice pathogenic fungi, Rhizoctonia solani and Pyricularia grisea was tested preliminarily using the agar plate protocol. Effects on mycelial growth, sclerotium and spore germination of the culture filtrate of Xenorhabdus strains that showed high inhibitory activities against the tested pathogens were examined further using plate dilution method. Cultural filtrate of YNa111 and YNd173 strains showed strong inhibitory activity against the growth of both pathogens in vitro. The relative inhibitory rate of YNa111 against R. solani was 100% and 82% for 40× and 160× diluted filtrate, respectively; while that of YNd173 against P. grisea was 88% and 76% for 5× and 10× diluted filtrate, respectively.