Location: Plant, Soil and Nutrition ResearchTitle: The tomato UV-damaged DNA-binding protein-1 (DDB1) is implicated in pathogenesis-related (PR) gene expression and resistance to Agrobacterium tumefaciens ) Author
Submitted to: Molecular Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/7/2012
Publication Date: 12/17/2012
Citation: Lui, J., Li, H., Miao, M., Tang, X., Giovannoni, J.J., Xiao, F., Liu, Y. 2012. The tomato UV-damaged DNA-binding protein-1 (DDB1) is implicated in pathogenesis-related (PR) gene expression and resistance to Agrobacterium tumefaciens. Molecular Plant Pathology. 13:123-134. Interpretive Summary: Plants are constantly exposed to potential pathogens, but are resistant to the majority of them. This is largely because plants use a complex of immune systems to defend themselves against pathogen invasion. Here we show that tomato plants deficient in a gene, DDB1, which we previously showed to be important for fruit quality, nutritional content and light responses, are also altered in their susceptibility to infection by Agrobacterium tumefaciens. These results demonstrate that DDB1 is a critical gene for multiple aspects of plant development, fruit quality and pathogen response.
Technical Abstract: Plants defend themselves against potential pathogens via the recognition of pathogen-associated molecular patterns (PAMPs). However, the molecular mechanisms underlying this PAMP triggered immunity (PTI) are largely unknown. In this study, we show that tomato HP1/DDB1, coding for a key component of the CUL4-based ubiquitin E3 ligase complex, is required for resistance to Agrobacterium tumefaciens. We found that the DDB1-deficient mutant (high pigment-1, hp1) is susceptible to nontumorigenic A. tumefaciens. The efficiency of callus generation from the hp1 cotyledons was extremely low as a result of the necrosis caused by Agrobacterium infection. On infiltration of nontumorigenic A. tumefaciens into leaves, the hp1 mutant moderately supported Agrobacterium growth and developed disease symptoms, but the expression of the pathogenesis-related gene SlPR1a1 and several PTI marker genes was compromised at different levels. Moreover, exogenous application of salicylic acid (SA) triggered SlPR1a1 gene expression and enhanced resistance to A. tumefaciens in wild-type tomato plants, whereas these SA-regulated defence responses were abolished in hp1 mutant plants. Thus, HP1/DDB1 may function through interaction with the SA-regulated PTI pathway in resistance against Agrobacterium infection.