Circadian Clock-Mediated Resistance to Green Peach Aphids

This study uncovered the involvement of CIRCADIAN CLOCK-ASSOCIATED1 (CCA1) in plant defense against aphids. Wild-type plants, coentrained with aphids in the same light/dark cycles, exhibited greater resistance than those preentrained in the opposite cycle, indicating the circadian clock's defensive role. Surprisingly, the arrhythmic CCA1 overexpression line (CCA1-OX) displayed enhanced resistance despite its loss of circadian regulation, underscoring CCA1's influence on both clock-dependent and -independent defense mechanisms. CCA1-mediated resistance was largely attributed to indole glucosinolates. Aphid feeding induced alternatively spliced CCA1a/b transcripts but not the fully spliced CCA1 transcripts, maximizing circadian-mediated defense while ensuring normal plant development.