Mitogen activated protein kinases function as a cohort during a plant defense response

ABSTRACT Mitogen activated protein kinases (MAPKs) play important signal transduction roles. However, little is known regarding whether MAPKs influence the gene expression of other family members and the relationship that expression has to a biological process. Transcriptomic studies have identified MAPK gene expression occurring within root cells undergoing a defense response to a pathogenic event in the allotetraploid Glycine max . Furthermore, functional analyses are presented for its 32 MAPKs revealing 9 of the 32 MAPKs have a defense role, including homologs of Arabidopsis thaliana MAPK (MPK) MPK2, MPK3, MPK4, MPK5, MPK6, MPK13, MPK16 and MPK20. Defense signal transduction processes occurring through pathogen activated molecular pattern (PAMP) triggered immunity (PTI) and effector triggered immunity (ETI) have been determined in relation to these MAPKs. PTI has been analyzed by examining BOTRYTIS INDUCED KINASE1 ( BIK1 ), ENHANCED DISEASE SUSCEPTIBILITY1 ( EDS1 ) and LESION SIMULATING DISEASE1 ( LSD1 ). ETI has been analyzed by examining the role of the bacterial effector protein harpin and the downstream cell membrane receptor NON-RACE SPECIFIC DISEASE RESISTANCE1 ( NDR1 ). Experiments have identified 5 different types of gene expression relating to MAPK expression. The MAPKs are shown to influence PTI and ETI gene expression and a panel of proven defense genes including an ABC-G type transporter, 20S membrane fusion particle components, glycoside biosynthesis, carbon metabolism, hemicellulose modification, transcription and PATHOGENESIS RELATED 1 ( PR1 ). The experiments show MAPKs broadly influence the expression of other defense MAPKs, including the co-regulation of parologous MAPKs and reveal its relationship to proven defense genes.