苹果内生细菌动态分布及其对斑点落叶病的拮抗作用

采用常规分离法对不同生长季节苹果树的不同部位进行了内生细菌分离．结果表明，内生细菌的分离几率和数量不同．通过平板对峙培养和发酵液抑菌活性测定，在所分离的118个菌株中，筛选出7株对苹果斑点落叶病菌（Alternaria alternata f．sp．Mali）具有较强拮抗作用的菌株，其中菌株B86和B91的发酵滤液在活体上对苹果斑点落叶病的防治效果显著，分别为73．72％和75．32％．两菌株培养滤液对病菌分生孢子萌发具有抑制作用，并造成芽管畸形膨大，呈泡囊状，泡囊消解破裂；两菌株产生的抑菌物质具有热稳定性．表明B86和B91菌株具有一定的生防潜力．

Dynamic distribution of endophytic bacteria in apple and their antagonism to the apple spot leaf drop

One hundred and eighteen strains of apple during the growing season through the endophytic bacteria were isolated from various organs of conventional separation method. The results indicated that the separation probability and the quantity of endophytic bacteria varied with seasons and organs. Strains B86 and B91 with strong antagonistic effect on Alternaria alternata f, sp, mali were screened out through dual-culture and inhibitory activity bioassay. Their fermentation filtrates had significant inhibitory effects upon the pathogen, with the inhibitory rates as 73.72 % and 75.32 %, respectively. Fermentation filtrates of B86 and B91 in medium had strong inhibition to the spore germination of the pathogen, The deformation and disintegration of the spore germ tubes were observed in the treatment of filtrates, The antifungal compounds of two strains were stable to the heat treatment, indicating that the strains B86 and B91 have the potential biological control function.