Characterization of a bacterial strain T132 and its effect on postharvest citrus anthracnose

Abstract:

[Objective] Citrus (Citri) is an economically important fruit crop in the world. The anthracnose caused by Colletotrichum gloeosporioides (Penz.) Sacc. is one of the main diseases in citrus production. For exploring of an effective biocontrol measure against citrus postharvest anthracnose, a bacterial biocontrol strain T132 isolated from the rhizosphere soil of citrus was identified and characterized. The efficacy of the biocontrol strain against citrus postharvest anthracnose disease was evaluated. [Methods] Identification of strain T132 was carried out by using 16S rDNA sequence homology comparison as well as morphological, physiological and biochemical characteristics. The antagonistic stability of the strain T132 was determined by continuously transferring it on artificial media for 8 generations. The efficacy of strain T132 in controlling citrus postharvest anthracnose was performed by stab inoculation and naturally infected methods. The use of specific primers detect the strain T132 of the pathogenic factor of Burkholderia cepacia as a potential human pathogens. [Results] Strain T132 was identified as Burkholderia vietnamiensis based on its morphological traits, phyiological and biochemical characters as well as 16S rDNA sequence analysis. Less change in the suppressive ability of antagonizing against growth of C. gloeosporioides was observed during 8 generations of transfers on artificial media. The strain T132 had significant efficacy in controlling citrus anthracnose disease causing by C. gloeosporioides. The average efficacies of the strain T132 in controlling the disease were 88.2% in artificial inoculation test and 54.9% in natural infection test 20 d and 60 d after of the antangonist applications, respectively. It was no virulence gene of Burkholderia cepacia epidemic strain marker (BCESM) existed. [Conclusion] This is the first report of B. vietnamiensis as a biocontrol agent against citrus postharvest anthracnose disease and the relative safety of biocontrol strains on human.