不适温度条件诱导西瓜嗜酸菌进入VBNC状态的研究

由西瓜嗜酸菌(Acidovoraxcitrulli)引起的瓜类果斑病,是危害西瓜和甜瓜等葫芦科作物的一种典型的种传细菌性病害.已有文章报道西瓜嗜酸菌在铜离子诱导下可进入"有活力但不可培养"(viable but non-culturable,VBNC)状态,并在适当条件下复苏,成为生产中潜在的病害初侵染来源.本文结合实...

Study on induction of VBNC state in Acidovorax citrulli by unfavorable temperatures

Bacterial Fruit Blotch (BFB), caused by Acidovorax citrulli, is a typical seed-borne bacterial di-sease on cucurbitaceae crops, including watermelon and melon. It has been reported that A. citrulli can enter into the viable but non-culturable (VBNC) state induced by copper and resuscitate under appropriate conditions, which acted as a potential primary inoculum source in the field. In this study, bacterial cells of A. citrulli strain AAC00-1 was treated at 50℃, 55℃ and 4℃, respectively, which artificially stimulated the temperatures of hot water treatment and seed storage in production. The viability and culturability of A. citrulli cells were determined by flow cytometry (FCM) and agar plating, respectively. It showed that AAC00-1 can enter into VBNC state by unfavorable temperatures. All viable cells of AAC00-1 entered into the VBNC state after treated at 55℃ for 20 min and 30 min. The treated bacterial suspensions of AAC00-1 were injected into the cotyledon of watermelon seedlings for pathogenicity test. The inoculated plants showed no symptoms of BFB, and no culturable cells can be isolated from the inoculated seedlings. This indicates that VBNC cells of AAC00-1 can not be resuscitated in vivo in watermelon seedling. This study analyzed the ability of A. citrulli to enter into the VBNC state under unfavorable temperature conditions, and provided a theoretical basis for primary inoculum of BFB in the field, which has important significance for controlling of BFB in cucurbits production.