Plant Defense against Insect Herbivory is Mediated by the Circadian Clock
Master of Arts
Organisms on earth evolved a circadian clock that matches the planet's 24-hour rotation. The plant clock controls many behaviors and proper entrainment of the clock to the environment leads to a competitive overall growth advantage. Despite the finding that many wound-inducible genes are also circadian regulated, it was uncertain whether this regulation is important for plant defense against herbivorous insects. We found that plants entrained to light-dark cycles 12 hours out of phase with the predator, Trichoplusia ni (cabbage loopers), were more susceptible to T. ni herbivory than plants entrained in phase with T ni . In contrast, arrhythmic clock and jasmonate-deficient mutants were equally susceptible to T. ni herbivory whether entrained in the same or reciprocal 12-hour light-dark cycles. These results suggest that the circadian rhythms, acting through jasmonate signals and the clock, add selective advantage to plants through enhanced anticipation of and defense against herbivory.
Biological sciences; Plant biology