514 / 2019-03-01 12:48:09

Young leaves of Arabidopsis thaliana provide a model system to investigate carotenogenesis and chloroplast development

carotenoid,,chloroplast,Arabidopsis thaliana,photosynthesis,chlorophyll

全体主题 > Metabolism

How chloroplasts orchestrate developmental and environmental cues to maintain carotenogenesis in leaves can be confounded by changes in cell division and expansion during leaf maturation. We revealed that the young leaves of Arabidopsis accumulate higher carotenoid levels compared to mature leaves. The changes in foliar carotenoid content were not linked to leaf phase identity or enzymatic oxidation. Neither the loss of function or overexpression of enzymes catalysing carotenoid biosynthesis affected the age-related decline in foliar pigment levels. However, the carotenoid isomerase (crtiso) mutant reduced total carotenoid and chlorophyll accumulation in younger, but not older leaves. The incubation of Arabidopsis rosettes in norflurazon caused a reduction in foliar pigments while accumulated 2- to 6-fold higher phytoene in young leaves compared to that in old leaves. Exposure to a non-freezing cold temperature or darkness also reduced pigment levels in young leaves mimicking the norflurazon effect. We reason that retrograde signals induced by crtiso, NFZ, cold and darkness can affect chloroplast development in rapidly dividing and/or expanding cells in young leaves. We propose that the higher level of carotenoids in younger leaves may be caused by a greater cell density and hence higher plastid capacity. Young leaves can, thus, provide an in-planta model system to decipher how developmental and environmental signals can affect chloroplast development and carotenogenesis.