Studies On The Isolation Of Burkholderia Glumae And The Relationship Between Rice Varieties' Endogenous Hormone And Resistance

Rice disease caused by Burkholderia glumae is an increasingly important disease in global rice production.B.glumae could cause both seedling and panicle disease of rice,called bacterial seedling rot of rice(BSRR)and bacterial panicle blight of rice(BPBR),respectively,which are seriously threating the high and stable-yield production of rice.In this paper,the pathogens from BPBR-like rice samples,collected from Guangxi,Guangdong,Fujian,and Zhejiang provinces,were isolated and identified.Meanwhile,the rice resistance of rice to BPBR at seedling stage was preliminarily tested.On the basis of the selected resistance rice varieties,the relationship between endogenous hormones and rice seedling resistance was determined.The effect of exogenous salicylic acid on seedling resistance was also verified.The main results were as follows:1.B.glumae was easely isolated from infecting r:ice by inoculating in NA medium contained ampicillin(50 ?g/mL)and cultivating at 37? for 24 h.2.By using the optimized isolation method,61 strains were isolated from 43 BPBR-like rice samples.3.The results of the test for rice resistant varieties at seedling stage by using seed treatment,dipping seedling root and spraying seedling with B.glumae strain LMG2196 showed that Zhendao11,Xiushui09,Nipponbare,Xiushui134 were resistant to BPBR,and Zhongjiazao17,Xiangzaoxian,C64-7,C98,BL-7 were susceptible to BPBR.4.Ten varieties,which showed resistant,middle-resistant and susceptible to BPBR at seedling stage,were used to test their resistance at booting stage.Results showed that the resistance in the most of varieties was consistent with the result at seedling stage and booting stage.However,it was more resistant to BPBR at seedling stage than booting stage in the some variety.5.The susceptible cultivar Zhongjiazao17 and resistant cultivar Zhendaol 1 were treated by injecting B.glumae suspension at seedling stage,and determined the contents of endogenous hormones.The changes of endogenous hormone contents in the two cultivars were significant compared with the corresponding controls,respectively.The result showed that the contents of JA and SA were significantly up-regulated,and the increase of ZT was relatively insignificant.The contents of GA3,ABA and IAA were reduced in the initial stage after inoculation,and changed of a fluctuating in the later stage.The content of BR was also reduced.There was a difference in the variation trend among different resistance varieties,and the change is more significant in the resistance varieties than that in susceptible.6.The rice seedlings after spraying with exogenous SA could significantly reduce the severity of BPBR,and its effect was related to inducing the defense enzyme activity of rice seedlings.The activity and contents of CAT,POD and SOD in rice seedlings treated with SA increased obviously and rapidly,and could reach a higher level in a short time.