Dance of plants with circadian clock

Abstract

Endogenous oscillator called circadian clock controls many physiological aspects. Since the identification of LATE ELONGATED HYPOCOTYL (LHY) and CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) genes as the 1st candidates for clock components in plants, many clock-associated genes have been identified in Arabidopsis and other plant species. The 1st negative feedback model composed of LHY, CCA1 and TIMING OF CAB EXPRESSION 1 (TOC1) has recently been modified based on possible functions of new players. Photoperiodic flowering is controlled by clock and our knowledge on molecular mechanisms underlying the clock-controlled process has much advanced in this decade. Recently, we have started to understand how the clock regulates organ movements and elongations in a model plant, Arabidopsis. In this short review, i) a history of construction of models on circadian rhythms in Arabidopsis, ii) modified models on circadian system in Arabidopsis, iii) recent progress on understanding molecular mechanisms underlying organ movements controlled by a circadian clock and iv) advantages of using tomato as a model system for chronobiology are summarized and discussed.