title: Altered levels of the Taraxacum kok-saghyz (Russian dandelion) small rubber particle protein, TkSRPP3, result in qualitative and quantitative changes in rubber metabolism.
abstract: Several proteins have been identified and implicated in natural rubber biosynthesis, one of which, the small rubber particle protein (SRPP), was originally identified in Hevea brasiliensis as an abundant protein associated with cytosolic vesicles known as rubber particles. While previous in vitro studies suggest that SRPP plays a role in rubber biosynthesis, in vivo evidence is lacking to support this hypothesis. To address this issue, a transgene approach was taken in Taraxacum kok-saghyz (Russian dandelion or Tk) to determine if altered SRPP levels would influence rubber biosynthesis. Three dandelion SRPPs were found to be highly abundant on dandelion rubber particles. The most abundant particle associated SRPP, TkSRPP3, showed temporal and spatial patterns of expression consistent with patterns of natural rubber accumulation in dandelion. To confirm its role in rubber biosynthesis, TkSRPP3 expression was altered in Russian dandelion using over-expression and RNAi methods. While TkSRPP3 over-expressing lines had slightly higher levels of rubber in their roots, relative to the control, TkSRPP3 RNAi lines showed significant decreases in root rubber content and produced dramatically lower molecular weight rubber than the control line. Not only do results here provide in vivo evidence of TkSRPP proteins affecting the amount of rubber in dandelion root, but they also suggest a function in regulating the molecular weight of the cis-1, 4-polyisoprene polymer.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Nevada, Reno, NV 89557, USA.
authors.forename: Jillian
authors.initials: J
authors.lastname: Collins-Silva
authors.forename: Aise Taban
authors.initials: AT
authors.lastname: Nural
authors.forename: Amanda
authors.initials: A
authors.lastname: Skaggs
authors.forename: Deborah
authors.initials: D
authors.lastname: Scott
authors.forename: Upul
authors.initials: U
authors.lastname: Hathwaik
authors.forename: Rebekah
authors.initials: R
authors.lastname: Woolsey
authors.forename: Kathleen
authors.initials: K
authors.lastname: Schegg
authors.forename: Colleen
authors.initials: C
authors.lastname: McMahan
authors.forename: Maureen
authors.initials: M
authors.lastname: Whalen
authors.forename: Katrina
authors.initials: K
authors.lastname: Cornish
authors.forename: David
authors.initials: D
authors.lastname: Shintani
mesh_terms: D018506:Gene Expression Regulation, Plant; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012408:Rubber / Q000378:metabolism*; D031205:Taraxacum / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors
chemical_list: D010940:Plant Proteins; D012333:RNA, Messenger; D012408:Rubber