The circadian clock component LUX ARRHYTHMO regulates Arabidopsis defense through salicylic acid
H. LU (1), C. Zhang (1), N. Seitz (2), W. Angel (1), D. Lin (1), A. Hallworth (1) (1) University of Maryland Baltimore County, U.S.A.; (2) University of Maryland Baltimore County, Canada

Recent studies showed that two morning clock genes regulate Arabidopsis defense independently of the key defense signaling mediated by salicylic acid (SA). To further understand the defense role of the circadian clock, we tested a mutant impaired in the evening clock gene LUX ARRHYTHMO in defense responses. We found that the lux-1 mutant was compromised to both basal and R-gene mediated defense against Pseudomonas syringae . We also found that lux-1 had transiently reduced SA accumulation after infection with a virulent P. syringae strain. Consistent with these results, the double mutant acd6-1lux-1 displayed suppression on dwarfism, cell death, and constitutive defense phenotypes, compared with acd6-1, which has been used as a convenient genetic tool in gauging the change of defense levels. We further found that two downstream targets of LUX also modulated resistance to P. syringae via the SA pathway. Together our results showed that LUX regulates Arabidopsis defense, possibly through affecting SA signaling. These data further support crosstalk between the circadian clock and plant innate immunity and also reveal different molecular mechanisms underlying clock-defense crosstalk.

Abstract Number: P18-683
Session Type: Poster