Abstract
Chlorophyll b reductase catalyzes the conversion of chlorophyll b to chlorophyll a. In this study, we investigated the functions of two chlorophyll b reductase isoforms, namely, AtNYC1 and AtNOL, in Arabidopsis thaliana. The AtNYC1 gene was predominantly expressed during leaf senescence, while the AtNOL gene was constitutively expressed in leaves. An AtNYC1 knock-out mutant showed the stay-green phenotype during leaf senescence. Degradation of chlorophyll b, carotenoids, and LHCII was markedly retarded in the mutant. In contrast, the AtNOL knock-out mutant didn't show an obvious stay-green phenotype. These results indicate that AtNYC1 and AtNOL have distinct and independent physiological functions in Arabidopsis thaliana. Furthermore, we examined the in-vivo activity of AtNOL and found that the enzyme was able to convert the chlorophyll b molecules bound to LHCII.
