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CORESTA Congress, Kunming, 2018, Agronomy/Phytopathology Groups, AP 48

The NSm of tomato spotted wilt virus is an elicitor of RTSW-mediated virus resistance in tobacco and its ability in HR induction is dissociated of movement function

HUANG Changjun; LIU Yong; YUAN Cheng; ZENG Jianmin; YU Haiqin; GAO Yulonng; XIAO Bingguang
Yunnan Academy of Tobacco Agricultural Sciences of CNTC, Kunming City, Yunnan Province, P.R. China

Tomato spotted wilt virus (TSWV, order Bunyavirales, family Tospoviridae and genus Orthotospovirus) is one of the most destructive viral pathogens of plants. Recently, a single dominant gene conferring complete resistance to TSWV (RTSW) was found in a wild tobacco, Nicotiana alata, and has been introgressed into cultivar tobacco. However, whether there is a TSWV avirulence (Avr) factor against RTSW remains obscure. To identify the Avr factor corresponding to RTSW in TSWV, Agrobacterium-mediated transient expression of TSWV open reading frames (ORFs) in TSWV-resistant (RTSW) and -susceptible (rtsw) tobacco plants was conducted. Hypersensitive response (HR)-type cell death was observed only when NSm of TSWV was expressed in RTSW-bearing tobacco leaves in a genotype-specific manner. To clarify whether the movement function of NSm is coupled with its function in HR elicitation, a series of movement-defective mutants were generated. Amino acids (aa) substitution mutagenesis indicated that the NSm mutants defective in targeting plasmodesmata and cell-to-cell movement were still capable of inducing RTSW-mediated HR. Collectively, our results clearly demonstrated that RTSW-mediated resistance is triggered by the TSWV movement protein but is independent of its movement function.