Modulation of chlorophyll b biosynthesis and photosynthesis by overexpression of chlorophyllide a oxygenase (CAO) in tobacco

Abstract

Chlorophyll (Chl) b is synthesized by oxidation of a methyl group on the B ring of the porphyrin molecule to a formyl group by chlorophyllide (Chlide) a oxygenase (CAO). The overexpression of Arabidopsis thaliana full length CAO (AtCAO) in tobacco (Nicotiana tabacum) resulted in an increased Chl synthesis and a decreased Chl a/b ratio in low-light-grown (LL) as well as in high-light-grown (HL) tobacco plants, where the effect was more pronounced. In HL-plants, increased [Chl b] resulted in efficient capture of solar energy and enhanced (40%–80%) electron transport rates at both limiting and saturating light intensities.