The wound response of tomato (Solanum lycopersicum) provides an attractive model to understand the signal transduction events leading from localized injury to the systemic expression of defense-related genes. A wealth of evidence indicates that the peptide signal systemin and the phytohormone jasmonic acid (JA) work together in the same signaling pathway to activate the expression of PIs and other defense-related genes. The systemin/JA signaling pathway provides a unique opportunity to investigate, in a single experimental system, the mechanism by which peptide and oxylipin signals interact to coordinate plant systemic immunity.

 

Scientists in Dr. Chuanyou Li’s group from the Institute of Genetics and Development Biology, the Chinese Academy of Sciences, described the characterization of the tomato suppressor of prosystemin-mediated responses8 (spr8) mutant, which was isolated as a suppressor of (pro)systemin-mediated signaling. spr8 plants exhibit a series of JA-dependent immune deficiencies, including the inability to express wound-responsive genes, abnormal development of glandular trichomes, and severely compromised resistance to cotton bollworm (Helicoverpa armigera) and Botrytis cinerea. Map-based cloning studies demonstrate that the spr8 mutant phenotype results from a point mutation in the catalytic domain of TomLoxD, a chloroplast-localized lipoxygenase involved in JA biosynthesis. The wound-induced expression of TomLoxD is directly regulated by the transcription factor SlMYC2. They also provided evidence that overexpression of TomLoxD enhanced resistance to insect herbivory attack and necrotrophic pathogen infection, but had no side effect on general plant growth. These results highlight the application potential of TomLoxD for crop protection against insects and pathogens.

 

This work with Ph.D. Student Liuhua Yan, Dr. Qingzhe Zhai and Dr. Jianing Wei (Institute of Zoology, Chinese Academy of Sciences) as the co-first authors has been published in PLoS Genetics (DOI: 10.1371/journal.pgen.1003964). This research was supported by grants from the Ministry of Agriculture of China, the Ministry of Science and Technology of China and the Beijing Natural Science Foundation.

 

AUTHOR CONTACT:

Chuanyou Li, Group Leader

Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.

E-mail: cyli@genetics.ac.cn