Studies On Bacterial Spot Of Tomato Leaves In Gansu Province

Bacterial spot of tomato leaves(Pseudomonas syringae), was widely dispersed in hexi Gansu, which brought about enormous economic losing to the peasants. Based on investigation in Zhangye Gansu province from 2006 and 2007, it was found that the similar disease developed seriously .The investigation indicated that the incidence of the similar disease was over 40%, more seriously 100%, which led to the decreasing of the production and quality of the processed tomato. So pathogenic bacteria were isolated and purified from disease leaves for further study in 2006 and 2007. Molecular biology 16SrDNA was used to identify pathogen and pathonenicity and host range were also examined in this paper. In additional, the resistance was investigated on 64 tomato cultivars. The data were given on the production of the processed tomato. The results were as following:1 Test of pathonenicity and host range of Bacterial Spot of Tomato LeavesThe typical pathogenic strain YB1,YB2,YB10,YB11 was selected from 15 bacterial strains isolated from tomatoes in Hexi Gansu province. Through Pathogenicity test , the result indicated that tomato was infected by the strain YB1,YB2,YB10,YB11. and through host range test , the result indicated that not only tomato,pepper,eggplant, solanaceae plants,but also cucumber,watermelon,wax-gourd,muskmelon,gourd plants and bean,cowpea,cabbage,downspout,cruciferae plants were infected by strain YB1,YB2.2 16SrDNA Identification of Pathogen of Bacterial Spot of Tomato LeavesDNA of pathogenic bacteria YB1,YB2,YB10,YB11was extracted for PCR amplification. By comparing the sequence with known sequence in GenBank, it indicated that the gene sequence of the YB1,YB2 were homogeneous at the rate of 99% to the members of Pseudomonas syringe. Therefore, the position of strainYB1,YB2 in bacterial phylogeny were preliminarily established , and it was identified that Pseudomonas syringae (Van Hall) was pathogen of local Bacterial Spot of Tomato Leaves. The gene sequence of the YB10 was homogeneous at the rate of 99% to the members of Pseudomonas fulva. it was identified that Pseudomonas fulva. The gene sequence of the YB11 was homogeneous at the rate of 99% to the members of Curtobacterium flaccumfaciens pv flaccumifaciens, it was identified that Curtobacterium flaccumfaciens pv flaccumifaciens.3 Investigation on the resistance of Pathogen of Bacterial Spot of Tomato LeavesBy comparing the infection index of Bacterial spot of tomato leaves of 64 tomato cultivars,it was found that there was the significantly different resistance among the tomato cultivars. The infection index of Bacterial spot of tomato leaves of the tomato cultivars of high resistant to diseases is in 0-5.The repsentative cultivars are ZOO-73,06-2,06-4,06-1,Q018.The infection index of Bacterial spot of tomato leaves of the tomato cultivars of middle resistant to diseases is in 5-10.The repsentative cultivars are 87-5,170,3155,T05-8,153,06-8. The infection index of Bacterial spot of tomato leaves of the tomato cultivars of middle susceptible to diseases is in 10—15. The repsentative cultivars are TOM608R,Q022,SM07,06-12,SH5. The infection index of Bacterial spot of tomato leaves of the tomato cultivars of high susceptible to diseases is in 10—15. The repsentative cultivars are HONGBAOSHI,SHIHONG7,KANGJIA2,QUPIDAGUO,99,SHIHONG4。4 Investigation on the occurrence course of Pathogen of Bacterial Spot of Tomato LeavesBy investigation on the occurrence course of pathogen of Bacterial spot of tomato leaves, the result showed that the incidence and the infection index were increased widely, from 13.3% to 45% and from 4.3 to 10 respectively,in 24th July-2th August. The incidence and the infection index were stable in 2th -5th August.The incidence was appromixely 45%, the infection index was appromixely 10.After it happened,it enlarged from nether leaves to upper leaves,which make leaves wilt.The disease happened seriously in rainfall days,which resulted in the disease prevail.