Chemotaxis Detection And Functional Analysis Of CheA And CheY Gene In Chemotaxis System Of Acidovorax Citrulli

Bacterical Fruit Blotch(BFB) is a worldwide quarantine disease, mainly infecting watermelon, melon, and other cucurbitaceae crops, causing significant economic loss. BFB is caused by Acidovorax citrulli, seeds with bacteria are the mainly source of infection. Pathogenic bacteria’s colonization in host is much close with pathogenicity, and chemotaxis is a key factor to the colonization of Acidovorax citrulli. This paper is mainly about chemotaxis detection and functional analysis of che A and che Y3 gene in chemotaxis system of Acidovorax citrulli. The results are as following:1. Preliminary detection of Chemotaxis of Acidovorax citrulliCapilary method was used to study the effect of carbon, amino acids, organic acid, and so on, on the chemotixis of Acidovorax citrulli. The results showed that among the carbon resourses, maltose, glucose, lactose, sucrose, galactose significantly promoted; among the amino acids, L-tryptophan, L-isoleucine, L-leucine, L-valine, L-proline and L-alanine significantly promoted, while L-methionine significantly inhibited; among the organic acid, citric acid and malic acid significantly promoted its chemotaxis; other substance such as Nacl and Mg SO4 had no significant influence on its chemotaxis.2. Bioinformatics analysis of che A and che Y gene in chemotaxis system of Acidovorax citrulliWe found some information about che A and che Y gene at NCBI.database. che A and che Y geencodes Che A and Che Y respectively. Che A and Che Y both has many hydrophobic amino acids. Che A has transmembrane domains at site of 600-700 amino acid, Che Y has no transmembrane domain, receiving signal of Che A. Che A of Acidovorax citrulli is closest to Che A of Ralstonia solanacearum, and farthest to Che A of Pseudomonas flurescens.3. the function of che A and che Y3 in chemotaxis system of Acidovorax citrulliConstructed mutant strains Δche A, Δche Y3 and complementary strain Cche A, and tested their phenotype. We found that compared with wide type Ac-5, the chemotaxis and motility, the colonization on the seeds of the mutant strains Δche A and Δche Y3 both reduced; The disease index of diseased leaf first reduced, then increased to the level of the wide type Ac-5; the formation of biofilm increased; all caused hypersensitive response.4. Expression of related genes because of the lack of che AUsing q PCR, we analyzed the influence of the lack of che A. The results showed that their was no expression of che A, hrc N and hrp E of type III secretion system, toxic gene trb C and vir B, the synthetic gene mot A and dynein gene fli M of flagellar, the signal reception gene che Y1, all increased.