Mechanisms Of Chitosan Solution On Acidovorax Avenae Subsp. Citrulli And Differential Expression Of Membrane Proteins Of Acidovorax Avenae Subsp. Avenae Under Multi-conditions

The in vitro antibacterial effect of chitosan and its ability in protection of watermelon seedlings from bacterial fruit blotch were evaluated. Results showed that three types of chitosan, in particular, chitosan A significantly inhibited the growth of Acidovorax citrulli. The antibacterial activity of chitosan was affected by deacetylation degree, chitosan concentration and incubation time. The disease index in soil and the death rate in perlite were significantly reduced by chitosan A compared to the pathogen control. Moreover, fresh and dry weight of watermelon seedlings planted in soil was increased by chitosan seed treatment, but not by chitosan leaf spraying. The integrity of the cell membrane and transmission electron microscopic observation were conducted. Results showed that chitosan played a strong role in the destruction of the cell membrane. In addition, chitosan had no significant effect on the activities of defense enzymes in seedling inoculated pathogens compared to the control. The control mechanisms of chitosan may be attributed to the direct antibacterial activity, membrane lysis then bacterial death.Differential expressions of membrane proteins of RS-1strain under in vitro, in vivo and coculture with R456were conducted, and comparative analysis with genome wide predicted T6SS proteins as well. Results showed that some proteins like surface anchored protein F, ATP-dependent Clp and OmpA/MotB only presented under in vivo. In particular, OmpA/MotB was T6SS core components, demonstrating that T6SS may be involved in the survival and pathogenicity of A. avenae subsp. avenae strain RS-1in host plants. Under coculture condition, the secretions of R456could interfere with the protein expression of RS-1significantly, stimulating secretion of some proteins which associated with metabolism, identification and so on.