Table of Contents
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ON THE COVER
Crassulacean acid metabolism (CAM) is a highly water-use-efficient metabolic adaptation of photosynthetic CO2 fixation that is under strict temporal control mediated by the endogenous circadian clock. Boxall et al. (pages 2519–2536) investigated the importance of a key circadian clock-controlled protein kinase, phosphoenolpyruvate carboxylase kinase (PPCK), for optimized primary nocturnal CO2 fixation during CAM. The CAM-associated PPCK1 gene was silenced using an RNAi approach in the model CAM species Kalancho fedtschenkoi. Two-thirds of nocturnal CO2 fixation was lost in the absence of PPCK1, and this led to feedback misregulation of key genes within the core circadian oscillator. The cover image shows the succulent, CAM-performing leaves of K. fedtschenkoi plants, a species that is endemic to Madagascar. The leaves in the center display characteristic adventitious leaf margin plantlets, a valuable trait for rapid clonal propagation of stable transgenic lines.