Uncovering mechanisms of rubber biosynthesis in Taraxacum koksaghyz – role of cis‐prenyltransferase‐like 1 protein

Abstract

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 (cisPT) enzyme family, catalyzes the elongation of the rubber chains. An active rubber transferase heteromer requires a cisPT subunit (CPT) as well as a CPT‐like subunit (CPTL), of which T. koksaghyz has two homologous forms: TkCPTL1 and TkCPTL2, which potentially associate with the rubber transferase complex. Knockdown of TkCPTL1, 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 TkCPTL1‐RNAi plants revealed particles that were similar to native rubber particles regarding their particle size, phospholipid composition, and presence of small rubber particle proteins (SRPPs). We found that the particles encapsulated triterpenes in a phospholipid shell stabilized by SRPPs. Conversely, downregulating the low‐expressed TkCPTL2 showed no altered phenotype, suggesting its protein function is redundant in T. koksaghyz. MS‐based comparison of latex proteomes from TkCPTL1‐RNAi 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.

Latex Metabolome of Euphorbia Species: Geographical and Inter-Species Variation and its Proposed Role in Plant Defense against Herbivores and Pathogens

“…These results reveal the existence of a systematic defense mechanism with a complementary effect between rubber and cycloartanol. This is supported by reports of the decrease in the expression of rubber synthesis genes when the expression of triterpene synthesis genes increases (Niephaus et al 2019;Post et al 2012). This was all reflected in the metabolome of the latex of E. palustris during fungal infection (Krstić et al 2016).…”

Current trends in bio‐based elastomer materials

“…Therefore, it is also subject to SIC and exhibits good mechanical properties. [82][83][84] Its production can be increased by the following four strategies: (I) Seeking new Taraxacum species 85 ; (II) genetic modification of TK and biosynthesis [86][87][88][89] ; (III) improving cultivating conditions of TK 76,90,91 ; (IV) optimizing extraction procedure of TKS.…”

Reconstitution of prenyltransferase activity on nanodiscs by components of the rubber synthesis machinery of the Para rubber tree and guayule

“…cPTL proteins associated with rubber particles have also been identified in other NR-producing plants including lettuce ( Lactuca sativa ) and Russian dandelion, and knockdown of the genes encoding these proteins was found to reduce rubber content 4 , 11 , 12 . These in vivo findings thus implicated cPTL as a key player in NR biosynthesis.…”