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Identification and Characterization of Suppressor Mutants of spl11-Mediated Cell Death in Rice

June 2014 , Volume 27 , Number  6
Pages  528 - 536

Gautam S. Shirsekar,1 Miguel E. Vega-Sanchez,1 Alicia Bordeos,2 Marietta Baraoidan,2 Andrew Swisshelm,1 Jiangbo Fan,1,3 Chan Ho Park,1 Hei Leung,2 and Guo-Liang Wang1,3

1Department of Plant Pathology, Plant Molecular Biology and Biotechnology Program, The Ohio State University, Columbus, OH 43210, U.S.A.; 2International Rice Research Institute (IRRI), DAPO Box 7777, Metro Manila, Philippines 3State Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China

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Accepted 20 January 2014.

Lesion mimic mutants have been used to dissect programmed cell death (PCD) and defense-related pathways in plants. The rice lesion-mimic mutant spl11 exhibits race nonspecific resistance to the bacterial pathogen Xanthomonas oryzae pv. oryzae and the fungal pathogen Magnaporthe oryzae. Spl11 encodes an E3 ubiquitin ligase and is a negative regulator of PCD in rice. To study the regulation of Spl11-mediated PCD, we performed a genetic screen and identified three spl11 cell-death suppressor (sds) mutants. These suppressors were characterized for their resistance to X. oryzae pv. oryzae and M. oryzae and for their expression of defense-related genes. The suppression of the cell-death phenotypes was generally correlated with reduced expression of defense-related genes. When rice was challenged with avirulent isolates of M. oryzae, the disease phenotype was unaffected in the sds mutants, indicating that the suppression might be Spl11-mediated pathway specific and may only be involved in basal defense. In addition, we mapped one of the suppressor mutations to a 140-kb interval on the long arm of rice chromosome 1. Identification and characterization of these sds mutants should facilitate our efforts to elucidate the Spl11-mediated PCD pathway.

© 2014 The American Phytopathological Society