Gene expression profile of <italic>Ralstonia Solanacearum</italic> for the rhizosphere ecological niche of <italic>Solanum tuberosum</italic>.

Abstract: Plant root secretion can be regarded as signal molecules, which exerts impact on microorganisms in the rhizosphere ecological niche. We obtained gene expression profile of <italic>Ralstonia solanacearum</italic>PO41 under the root secretions environment of <italic>Solanum tuberosum</italic> at the time points of 8 hrs, 16 hrs and 24 hrs, respectively, after infection with RNA microarray technology. Bioinformatics tools of differential genes expression analysis, GO functional analysis, cluster analysis and pathway analysis were conducted to find out the pathogenic genes and other related genes. We found that the virulence factors of <italic>R. solanacearum</italic> mainly focused on the output pathways of toxic protein (Sec pathway, Tat pathway and type III secretion system (T3SS)), the aggregation and transfer of exopolysaccharides and the chemotactic movement and adhesion of flagellum in the potato root secretion ecological niche, while the virulence factors in the atypical output pathway mainly distributed in Sec (<italic>secB</italic>,<italic> secDF</italic>,<italic> yidc</italic>) and Tat (<italic>tatA</italic>,<italic> tatC</italic>) pathways to promote the output of folded and unfolded toxic proteins. The <italic>fli</italic><italic>I</italic>ATPase was obviously upregulated 8 hrs postinoculation, suggesting that type III secretion system was only active at the early stage of PO41 infection. The upregulated expression of phosphoglucomutase and epimerase showed that the virulence factor of exopolysaccharides (EPS) was synthesized at the early stage of <italic>R. solanacearum</italic> infection. Chemotactic receptor and motor protein were obviously upregulated within 24 hrs postinoculation. Our study revealed that <italic>R. solanacearum</italic>PO41 had already colonized to the roots within 24 hrs with the stimulating of root secretion. Some pathogenic genes were upregulated during this period. [ABSTRACT FROM AUTHOR]