Strategies utilized by plants to defend against Ralstonia solanacearum

Xue Dexing^1,2,3Wu Weifeng^1,2,4Kong Danyu^1,5,6*

• ¹Lushan Botanical Garden (CAS), Jiujiang, Jiangxi Province, China
• ²research assistant, Jiujiang, China
• ³xuedexing1986@163.com, Jiujiang, China
• ⁴wuwf@lsbg.cn, Jiujiang, China
• ⁵Associate Professor, Jiujiang, China
• ⁶kongdy@lsbg.cn, Jiujiang, China

Ralstonia solanacearum, the causal agent of bacterial wilt, is recognized as one of the most destructive vascular pathogens. The plant defense responses are gradually developed through long-term interactions with R. solanacearum.The plant cell wall integrity (CWI) system has evolved to initiate defense responses via a diverse array of plasma membrane-resident sensors. These defense responses result primarily from physical and chemical actions that counteract R. solanacearum infection. The plant cell wall serves as a defensive barrier against the pathogen including cellulose, hemicellulose, pectin, lignin and suberin. Various modifications to the cell wall and multiple changes in its composition are adopted by plants resistant to R. solanacearum.Physical confinement vertically or horizontally induced in xylem tissues are the most effective way to defend against R. solanacearum. The timely formation of tyloses and gels within the vessel lumen contribute to the suppression of R. solanacearum. Additionally, the deposition of callose at infected sites reinforce the cell wall, thereby preventing the further spread of R. solanacearum.Morphological modifications, such as the thickening of pit membranes and the increased number of larger xylem vessels play crucial roles in conferring resistance to R. solanacearum. Secondary metabolites act as phytoalexins used by plants against R. solanacearum. In this review, we discuss the strategies deployed by plants resistant to R. solanacearum. In particular, we outline physical and chemical restrictions as well as tissue constraints against the vascular pathogen.