Poster: Plant-pathogen interactions

Abs # 564: Molecular and Functional Characterization of a Jasmonic Acid-Inducible

Presenter:	Reyna, Nathan S, nreyna@uark.edu
Authors	Reyna, Nathan S (A)   Yang, Yinong  (A)
Affiliations:	(A): University of Arkansas, Plant Pathology Dept

Plant mitogen-activated protein kinases (MAPKs) are involved in a plethora of signaling pathways associated with both abiotic and biotic stresses and likely act as a converging point for different external stimuli. To date, most of the plant MAPKs that have been characterized are from dicotyledonous model species. In this study we characterized a novel jasmonic acid (JA) inducible rice MAPK gene (OsMPK6) that contains the TDY activation motif. The OsMPK6 cDNA is 2384 bp long and encodes a 599 -amino acid than control plants protein. The expression of OsMPK6 was very low in leaves, but relatively high in the sheath and culm of rice plants. Interestingly, OsMPK6 transcript levels, protein accumulation and kinase activity were specifically induced by JA, but not other defense signal molecules such as salicylic acid, benzothiadiazole, abscisic acid or ethylene. The rice blast fungus (Magnaporthe grisea) or its cell wall elicitor also rapidly (within 4 hrs) activated the expression of OsMPK6 in rice leaves or cell suspension cultures, respectively. To determine the biological function of OsMPK6, we have generated transgenic rice lines with overexpression (using an estradiol inducible promoter) or suppression (using RNA interference) of OsMPK6. Preliminary analysis indicates that the OsMPK6 overexpression lines appear to be hypersensitive to methyl JA as they show greater inhibition of coleoptile growth, as well as root length and number, than control plants. Pathological studies with the overexpression and suppression lines are being conducted and will be presented.