To investigate the role of SlWRKY15 in tomato basal defense responses
Date Issued
2012
Date
2012
Author(s)
Hu, Pei-Wen
Abstract
WRKY transcription factors (WRKYs) are encoded by large gene families in all higher plants. They are known to play pivotal roles in plant-specific processes, including plant responses to biotic and abiotic stresses. While analyzing tomato genes which are differentially expressed in response to infection by Phytophthora parasitica, we found a gene that is up-regulated and encodes a putative WRKY transcription factor, herein named SlWRKY15. The predicted amino acid sequence of SlWRKY15 contains a WRKY domain, a zinc-finger motif, nuclear localization signal, and a calmodulin binding domain. Analysis by semi-quantitative reverse transcriptase polymerase chain reaction indicated that SlWRKY15 is expressed in all parts of the tomato plant, with the messages in the flowers and stems being more abundant than those in other parts. Furthermore, expression of SlWRKY15 is induced following treatment of the plants with salicylic acid and ethylene. As well, expression of the homologs of SlWRKY15 in tobacco is induced by PAMPs from Phytophthora, including parA1 and pep13. To investigate its function, SlWRKY15 overexpressing plants were conducted by agroinfection and then inoculated the plants with P. parasitica and Ralstonia solnacearum. The results indicated that disease symptoms caused by either P. parasitica or R. solnacearum on plants overexpressing SlWRKY15 were less severe than those on the control plants. In contrast, down regulation of SlWRKY15 by virus-induced gene silencing enhanced the plant susceptibility s to these two pathogens. In plant overexpressing SlWRKY15, the expression of defense related genes (ACO1, PAL5, and PIN2) was down regulated. These results suggest a potential role of SlWRKY15 in the plant basal defense response, but how is it involved in the regulation of defense response awaits further investigation.
Subjects
Agroinfection,
PAMP-triggered immunity
Phytophthora
plant basal defense
Ralstonia solanacearum
tomato
virus-induced gene silencing
WRKY transcription factor
Type
thesis
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