title: Light-dependent regulation of chlorophyll b biosynthesis in chlorophyllide a oxygenase overexpressing tobacco plants.
abstract: Chlorophyllide a oxygenase (CAO) that converts chlorophyllide a to chlorophyllide b was overexpressed in tobacco to increase chlorophyll (Chl) b biosynthesis and alter the Chl a/b ratio. Transgenic plants along with their wild-type cultivars were grown in low and high light intensities. In low light there was 20% increase in chlorophyll b contents in transgenic plants, which resulted in 16% reduction in the Chl a/b ratio. In high light, total Chl contents were 31% higher in transgenic plants than those of wild type. The increase in Chl a was 19% and that of Chl b was 72% leading to 31% decline of Chl a/b ratio. The increase in Chl b contents was accompanied by enhanced CAO expression that was highly pronounced in low light. As compared to low light, in high light Lhcb1 and Chl a/b transcripts abundance was significantly increased in transgenic plants suggesting a close relationship between Chl b synthesis and cab gene expression. However, there was a small increase in expression of LHCII proteins, which did not correspond to 72% increase in Chl b content in transgenic line, implying that LHCPII has the ability to bind more Chl b molecules.
authors.affiliation: School of Life Sciences, Jawaharlal Nehru University, New Delhi 11067, India.
authors.forename: Gopal K
authors.initials: GK
authors.lastname: Pattanayak
authors.forename: Ajaya K
authors.initials: AK
authors.lastname: Biswal
authors.forename: Vanga S
authors.initials: VS
authors.lastname: Reddy
authors.forename: Baishnab C
authors.initials: BC
authors.lastname: Tripathy
mesh_terms: D017360:Arabidopsis / Q000235:genetics; D015152:Blotting, Northern; D015153:Blotting, Western; D002734:Chlorophyll / Q000096:biosynthesis*; D000077194:Chlorophyll A; D015870:Gene Expression; D005822:Genetic Vectors / Q000235:genetics; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism; D010105:Oxygenases / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D014026:Nicotiana / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism* / Q000528:radiation effects; D014170:Transformation, Genetic
chemical_list: D045342:Light-Harvesting Protein Complexes; D018749:RNA, Plant; D002734:Chlorophyll; C037184:chlorophyll b; D010105:Oxygenases; C115272:chlorophyll a oxygenase; D000077194:Chlorophyll A