[Isolation, identification and field control efficacy of an endophytic strain against tobacco bacterial wilt (Ralstonia solanacarum)].

In this paper, an endophytic strain B-001 against tobacco bacterial wilt (Ralstonia solanacarum) was isolated from the stem of healthy tobacco in R. solanacarum-infected fields, which had a stronger inhibitory effect on some kinds of gram-positive bacteria, gram-negative bacteria, and pathogenic fungi. This strain belonged to Bacillus, and its 16S rDNA after PCR and sequencing had an accession of GenBank being DQ444283. The 16S rDNA phylogenetic tree was constructed with MEGA3, and compared with the published 16S rDNA sequences of relative bacteria species. B-001 had a 99.2% sequence similarity with Bacillus subtilis (DQ415893). According to the morphological, physiological and biochemical characteristics, and based on phylogenetic analysis, B-001 was identified as a strain of B. subtilis. Field experiments in Guiyang and Ningxiang counties of Hunan Province showed that in 2005 and 2006, the control efficacy of B-001 on R. solanacarum ranged from 40.03% to 78. 14%, better than that of Streptomycini.