title: Overexpression of the HspL Promotes Agrobacterium tumefaciens Virulence in Arabidopsis Under Heat Shock Conditions.
abstract: Agrobacterium tumefaciens transfers a specific DNA fragment from the resident tumor-inducing (Ti) plasmid and effector virulence (Vir) proteins to plant cells during infection. A. tumefaciens VirB1-11 and VirD4 proteins assemble as the type IV secretion system (T4SS), which mediates transfer of the T-DNA and effector Vir protein into plant cells, thus resulting in crown gall disease in plants. Previous studies revealed that an α-crystallin-type, small heat-shock protein (HspL) is a more effective VirB8 chaperone than three other small heat-shock proteins (HspC, HspAT1, and HspAT2). Additionally, HspL contributes to efficient T4SS-mediated DNA transfer and tumorigenesis under room-temperature growth. In this study, we aimed to characterize the impact of HspL on Agrobacterium-mediated transformation efficiency under heat-shock treatment. During heat shock, transient transformation efficiency and VirB8 protein accumulation were lower in the hspL deletion mutant than in the wild type. Overexpression of HspL in A. tumefaciens enhanced the transient transformation efficiency in root explants of both susceptible and recalcitrant Arabidopsis ecotypes. In addition, the reduced transient transformation efficiency during heat stress was recovered by overexpression of HspL in A. tumefaciens. HspL may help maintain VirB8 homeostasis and elevate Agrobacterium-mediated transformation efficiency under both heat-shock and nonheat-shock growth.
authors.forename: Hau-Hsuan
authors.initials: HH
authors.lastname: Hwang
authors.forename: Yin-Tzu
authors.initials: YT
authors.lastname: Liu
authors.forename: Si-Chi
authors.initials: SC
authors.lastname: Huang
authors.forename: Chin-Yi
authors.initials: CY
authors.lastname: Tung
authors.forename: Fan-Chen
authors.initials: FC
authors.lastname: Huang
authors.forename: Yun-Long
authors.initials: YL
authors.lastname: Tsai
authors.forename: Tun-Fang
authors.initials: TF
authors.lastname: Cheng
authors.forename: Erh-Min
authors.initials: EM
authors.lastname: Lai
mesh_terms: D016960:Agrobacterium tumefaciens / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology; D017360:Arabidopsis / Q000382:microbiology*; D001426:Bacterial Proteins / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D006360:Heat-Shock Proteins / Q000235:genetics*; D006358:Hot Temperature; D010935:Plant Diseases / Q000382:microbiology*; D018517:Plant Roots / Q000382:microbiology; D010941:Plant Tumors; D010957:Plasmids / Q000235:genetics; D013312:Stress, Physiological; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D006360:Heat-Shock Proteins; C036483:T-DNA; D037521:Virulence Factors