Abstract:

The study aims to determine the species of blueberry crown gall pathogenic bacteria currently occurring in the main blueberry producing areas of Yunnan Province and screen the field control agents. Collecting blueberry crown gall disease samples from the main blueberry production areas in Yunnan, the symptoms of the disease, colony morphology, pathogenicity test, Biolog analysis and 16S rDNA sequence analysis were carried out for systematic identification. The agent screening test was conducted at the blueberry base with serious disease, and eight kinds of pesticides such as thiazinone and shenzemycin were used for field control experiments. The strain L-11 isolated and purified from blueberry crown gall disease samples could infect sunflower, tomato and blueberry plants, and the symptoms were similar to those in field. The strain with identical morphology was obtained by re-isolation. 16S rDNA sequence analysis and phylogenetic tree analysis showed that the sequence of L-11 strain and Agrobacterium tumefaciens strain Ell-7 (accession number: FJ613554.1) homology was up to 97.65%, and L-11 was on the same branch as A. tumefaciens. The specific fragment of 155 bp was amplified by the ipt specific primer AtP3F/AtP3R in L-11, which further confirmed that blueberry crown gall disease was caused by A. tumefaciens. The field efficacy test results showed that 1.5% thiazinone emulsion in water had a better control effect on blueberry crown gall disease, with a relative control effect of 52%. This is the first report of blueberry crown gall disease caused by A. tumefaciens in Yunnan.

Key words: blueberry crown gall disease, pathogenic bacteria, isolation, identification, Agrobacterium tumefaciens, pharmacy screening