Pathogen Identification Of Bacterial Speck Of Tomato And Screening Of Endophytic Bacteria

Tomato bacterial speck caused by Pseudomonas syringae pv.tomato(PST)is an important disease which could infact the production and quality of tomato.The disease could damage tomato leaves,stems,flowers,fruits and petiole.A similar bacterial disease in tomato was first found in Minqing,Fujian in 2006.15 strains were isolated from diseased stems and leaves of tomato.Following Kock's postulates,these strains could produce the same symptoms on the inloculated tomato plants.The similar bacterial strains were also isolated.All 15 isolates were identified as Pseudomonas syringae pv.tomato(Okabe)Young,Dye & Wilkie according to the pathogenicity,physiological and biochemical characterizations and 16S rRNA gene sequence analysis.For the growth of the strain,the minimum,maximum and optimum temperature range were 10,35,24-30℃,respectively.The lethal temperature was 49℃for 10 minutes.The optimum pH was 7.0.The result of biocontrol research showed that(1)28 strains were screened out from plant which obviously antagonized against the growth of Pseudomonas syringae pv.tomato.Among them the strain Fq7 was the best;(2)The strain Fq7 was identified as Bacillus subtilis by morphology and 16S rRNA gene sequence.(3)The strain Fq7 was used to control the disease indoor and the results showed that the control efficacy was 46.12%,57.30%and 62.71% when the tomato plants were inoculated with the strain for 4d,5d and 7d respectively.(4)The strain Fq7 was proved to be able to colonize inside of tomato when the bacterial suspention was innoculated by daubing leaves and pouring roots,the results also showed that the strain could transfer in plant tissue quickly.