title: CHRD, a plant member of the evolutionarily conserved YjgF family, influences photosynthesis and chromoplastogenesis.
abstract: Studies on the carotenoid-overaccumulating structures in chromoplasts have led to the characterization of proteins termed plastid lipid-associated proteins (PAPs), involved in the sequestration of hydrophobic compounds. Here we characterize the PAP CHRD, which, based on sequence homology, belongs to a highly conserved group of proteins, YER057c/YjgF/UK114, involved in the regulation of basic and vital cellular processes in bacteria, yeast and animals. Two nuclear genes were characterized in tomato plants: one (LeChrDc) is constitutively expressed in various tissues and the other (LeChrDi) is induced by stress in leaves and is upregulated by developmental cues in floral tissues. Using RNAi and antisense approaches, we show their involvement in biologically significant processes such as photosynthesis. The quantum yield of photosynthetic electron flow in transgenic tomato leaves with suppressed LeChrDi/c expression was 30-50% of their control, non-transgenic counterparts and was ascribed to lower PSI activity. Transgenic flowers with suppressed LeChrDi/c also accumulated up to 30% less carotenoids per unit protein as compared to control plants, indicating an interrelationship between PAPs and floral-specific carotenoid accumulation in chromoplasts. We suggest that CHRD's role in the angiosperm reproductive unit may be a rather recent evolutionary development; its original function may have been to protect the plant under stress conditions by preserving plastid functionality.
authors.affiliation: The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100, Israel.
authors.forename: Yael
authors.initials: Y
authors.lastname: Leitner-Dagan
authors.forename: Marianna
authors.initials: M
authors.lastname: Ovadis
authors.forename: Amir
authors.initials: A
authors.lastname: Zuker
authors.forename: Elena
authors.initials: E
authors.lastname: Shklarman
authors.forename: Itzhak
authors.initials: I
authors.lastname: Ohad
authors.forename: Tzvi
authors.initials: T
authors.lastname: Tzfira
authors.forename: Alexander
authors.initials: A
authors.lastname: Vainstein
mesh_terms: D000595:Amino Acid Sequence; D002338:Carotenoids / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism; D018553:Cucumis sativus / Q000235:genetics / Q000378:metabolism; D035264:Flowers / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D018551:Solanum lycopersicum / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010788:Photosynthesis / Q000235:genetics / Q000502:physiology*; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D018087:Plastids / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D020798:Two-Hybrid System Techniques
chemical_list: D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D002338:Carotenoids