CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) and the circadian control of stomatal aperture

Corresponding author: Rachel M. Green

The endogenous circadian (~24 hour) system allows plants to anticipate (预测) and adapt to daily environmental changes. Stomatal aperture (气孔孔径) is one of the many processes under circadian control; stomatal opening and closing occurs under constant conditions, even in the absence of environmental cues. To understand the significance of circadian mediated anticipation (预测) in stomatal opening, we have generated "SGC" Arabidopsis plants in which the oscillator gene (振荡基因) CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) was over-expressed under the control of the guard cell (保卫细胞) specific promoter, GC1. The SGC plants showed a loss of ability to open stomata in anticipation of daily dark to light changes and of circadian mediated stomatal opening in constant light (恒定光照). We observed that under fully-watered and mild drought (轻度干旱) conditions, SGC plants outperform (胜过) WT with larger leaf area and biomass. To investigate the molecular basis for circadian control of guard cell aperture, we used large scale qRT-PCR to compare circadian oscillator gene expression in guard cells compared with the "average" whole leaf oscillator and examined gene expression and stomatal aperture in several lines of plants with mis-expressed CCA1. Our results show that the guard cell oscillator is different from the "average" plant oscillator. Moreover, the differences in guard cell oscillator function may be important for the correct regulation of photoperiod pathway genes (光周期通路基因) that have previously been reported to control stomatal aperture. We conclude by showing that CONSTANS (CO) and FLOWERING LOCUS T (FT), components of the photoperiod pathway that regulate flowering time. also control stomatal aperture in a day-length dependent manner.

doi: https://doi.org/10.1104/pp.17.01214