Abstract:

Five hundred and eighty-seven bacterial isolates were obtained from different habitats（rhizosphere，endorhiza，surface and interior of stems，phyllosphere and endosphere）of field-grown cucumber plants and bulk soil. An assessment system was established to evaluate their biocontrol potential of 157 isolates strains according to in vitro activities of their extracellular metabolite（protease，chitinase，cellulase，glucanase and siderophores）. ARDRA analysis was performed to examine the genetic diversity of 157 isolates，of which 47 exhibiting relatively abundant genetic diversity was investigated for their biocontrol efficacy against CGMMV under greenhouse conditions. Nine bacterial isolates achieved positive biocontrol efficacy more than 40% at 30 days post pathogen inoculation（dpi）and HW2 strain can get at 57.02%. Among the 9 strains，one is from Stenotrophomonas maltophilia，others are from Bacillus sp. The conventional correlation efficient was 0.83 between the biocontrol efficacy of 47 isolates and their assessed biocontrol potential，indicating that the established assessment system was effective and can evaluate their biocontrol potential according to in vitro activities of their extracellular metabolites.

Key words: 黄瓜, 黄瓜绿斑驳花叶病毒, 菌株筛选, 酶活性测定, 聚类分析