Pathogenic Regulation Of L-glutamic Acid In Host Plants Against R.solanacearum GMI1000

Ralstonia solanacearum is a soil-borne phytopathogenic bacterium that can cause bacterial wilt in hundreds of plants,including potatoes,tomatoes,eggplant,peppers,tobacco and bananas by using a variety of complex strategies.Early studies have revealed that R.solanacearum could regulate its own motility in response to some exogenous organic acids or amino acids.However,whether R.solanacearum can utilize these compounds to enhance its own infection has not been clearly reported.This study consists of five parts: 1.The effect of tomato extract on the virulence factors of R.solanacearum GMI1000;2.Extraction,isolation and identification of the active substances in tomato extract and influences of active substances in virulence factors;3.Exploration of the components of signal transduction pathway in GMI1000;4.RNA-Seq and q RT-PCR analysis further analyzed the effect of the active ingredient on the expression levels of the related gene in R.solanacearum;5.Analysis of growth rate and pathogenicity in R.solanacearum in the absence and presence of active compound.The main results are listed as following:1.Tomato extract induces the production of virulence factors related to R.solanacearum GMI1000,including EPS production,cellulase activity,motility and biofilm formation.2.L-glutamic acid is an active component from the tomato extract and induces the production of virulence factors in R.solanacearum.3.A hybrid sensor histidine kinase/response regulator is involved in the signaling pathway activated by L-glutamic acid and it's an important component of the signaling pathway.4.Exogenous addition of L-glutamic acid affects the expression levels of a wide range of genes in GMI1000.In addition,RNA-Seq indicated that RS01577 also affects the expression levels of various genes related to extracellular polysaccharide secretion,motility,and virulence.5.Exogenous addition of tomato extract or L-glutamic acid enhances R.solanacearum virulence toward tomato plants.Moreover,addition of neither tomato extract nor L-glutamic acid could obviously enhance infection by the RS01577 deletion mutant,suggesting an important role of RS01577 in both the pathogenesis of R.solanacearum and the transduction of L-glutamic acid in the R.solanacearum wild-type strain.In conclusion,our results have established a new interaction mechanism between R.solanacearum and host plants,which highlights the complexity of the virulence regulation mechanism and may provide new insight into disease control.