UC San Diego

In a place teeming with pathogens, maintaining a defense mechanism against pathogen attacks is critical for survival especially when other stress factors such as drought can also endanger plant life, a staple of our agriculture. The phytohormone abscisic acid (ABA) regulates major abiotic stress responses, while the hormones salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) all participate in plant defense against pathogen invasions. Previous research has provided evidence for the antagonistic relationship between ABA signaling and pathogen resistance. To determine the range at which ABA signaling affects plant defense signaling, stomatal responses of pathogenic mutants were examined under treatments of ABA and C23, a synthetic chemical that inhibits ABA signaling and induces expression of defense genes. Results reveal that the convergence points between ABA and defense signaling occur upstream of SA synthesis and signaling. To identify a new mutant that is interconnected between the two pathways, mutant screening and genetic cloning of N277 is performed, a mutant line shown to exhibit insensitivity to ABA and to the C23 pathogen-induced inhibition of ABA signaling. This study aims to understand the mechanism at which ABA signaling interacts with pathogen defense signaling to enhance plant protection from pathogen invasions without decreasing crop yield