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Uncovering mechanisms of rubber biosynthesis in Taraxacum koksaghyz – role of cis‐ prenyltransferase‐like 1 protein
Author(s) -
Niephaus Eva,
Müller Boje,
Deenen Nicole,
Lassowskat Ines,
Bonin Martin,
Finkemeier Iris,
Prüfer Dirk,
Schulze Gronover Christian
Publication year - 2019
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.14471
Subject(s) - dandelion , natural rubber , isoprene , biosynthesis , protein subunit , biochemistry , hevea brasiliensis , prenyltransferase , chemistry , biophysics , biology , enzyme , organic chemistry , gene , polymer , alternative medicine , traditional chinese medicine , medicine , pathology , copolymer
Summary The Russian dandelion Taraxacum koksaghyz synthesizes considerable amounts of high‐molecular‐weight rubber in its roots. The characterization of factors that participate in natural rubber biosynthesis is fundamental for the establishment of T. koksaghyz as a rubber crop. The cis ‐1,4‐isoprene polymers are stored in rubber particles. Located at the particle surface, the rubber transferase complex, member of the cis ‐prenyltransferase ( cis PT ) enzyme family, catalyzes the elongation of the rubber chains. An active rubber transferase heteromer requires a cis PT subunit ( CPT ) as well as a CPT ‐like subunit ( CPTL ), of which T. koksaghyz has two homologous forms: Tk CPTL 1 and Tk CPTL 2, which potentially associate with the rubber transferase complex. Knockdown of Tk CPTL 1 , which is predominantly expressed in latex, led to abolished poly( cis ‐1,4‐isoprene) synthesis but unaffected dolichol content, whereas levels of triterpenes and inulin were elevated in roots. Analyses of latex from these Tk CPTL 1 ‐ RNA i plants revealed particles that were similar to native rubber particles regarding their particle size, phospholipid composition, and presence of small rubber particle proteins ( SRPP s). We found that the particles encapsulated triterpenes in a phospholipid shell stabilized by SRPP s. Conversely, downregulating the low‐expressed Tk CPTL 2 showed no altered phenotype, suggesting its protein function is redundant in T. koksaghyz . MS ‐based comparison of latex proteomes from Tk CPTL 1 ‐ RNA i plants and T. koksaghyz wild‐types discovered putative factors that convert metabolites in biosynthetic pathways connected to isoprenoids or that synthesize components of the rubber particle shell.