title: Suppression of a key gene involved in chlorophyll biosynthesis by means of virus-inducing gene silencing.
abstract: The ChlH gene coding the H subunit of magnesium chelatase, an enzyme involved in chlorophyll biosynthesis, was silenced in Nicotiana benthamiana plants by infection with tobacco mosaic virus vectors (pTMV-30b) containing 67,214 or 549 nt long ChlH inserts. Silencing of the nuclear ChlH gene induced a chimeric phenotype with green and yellow/white leaves associated with alterations of chloroplast shape and ultrastructure. The symptoms became first evident around veins of young leaves, and only later in the mesophyll tissues. The efficiency of gene silencing was not dependent on the insert orientation, but was strongly correlated with the size of the ChlH insert, providing a flexible method to modulate the level of gene suppression. Silencing efficiency seemed to be strongly dependent on endogenous ChlH mRNA level of the target tissue. Silencing of the ChlH gene with the longest fragment of 549 nt also lowered the accumulation of ChlD and chlorophyll synthetase mRNAs, i.e. other genes involved in chlorophyll biosynthesis.
authors.affiliation: Department of Biology, University of Turku, Finland. hiriart@utu.fi
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Hiriart
authors.forename: Kirsi
authors.initials: K
authors.lastname: Lehto
authors.forename: Esa
authors.initials: E
authors.lastname: Tyystjärvi
authors.forename: Teemu
authors.initials: T
authors.lastname: Junttila
authors.forename: Eva-Mari
authors.initials: EM
authors.lastname: Aro
mesh_terms: D019729:Carbon-Oxygen Ligases / Q000235:genetics / Q000378:metabolism; D002734:Chlorophyll / Q000096:biosynthesis* / Q000378:metabolism; D000077194:Chlorophyll A; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D008190:Lyases / Q000235:genetics* / Q000378:metabolism; D008854:Microscopy, Electron; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D044925:Oxidoreductases Acting on CH-CH Group Donors; D010641:Phenotype; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics / Q000821:virology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D021122:Protein Subunits; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012367:RNA, Viral / Q000235:genetics; D014026:Nicotiana / Q000201:enzymology / Q000235:genetics* / Q000821:virology; D014027:Tobacco Mosaic Virus / Q000235:genetics / Q000502:physiology*
chemical_list: D010940:Plant Proteins; D021122:Protein Subunits; D012333:RNA, Messenger; D012367:RNA, Viral; D002734:Chlorophyll; C037184:chlorophyll b; D010088:Oxidoreductases; D044925:Oxidoreductases Acting on CH-CH Group Donors; C023886:protochlorophyllide reductase; D008190:Lyases; C086788:magnesium chelatase; D019729:Carbon-Oxygen Ligases; C026901:chlorophyll synthetase; D000077194:Chlorophyll A