Post, J., van Deenen, N., Fricke, J., Kowalski, N., Wurbs, D., Schaller, H., Eisenreich, W., Huber, C., Twyman, Richard M., Prufer, D. and Gronover, C. S.. (2012) Laticifer-specific cis-prenyltransferase silencing affects the rubber, triterpene, and inulin content of taraxacum brevicorniculatum. Plant Physiology, Vol.158 (No.3). pp. 1406-1417. ISSN 0032-0889

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Abstract

Certain Taraxacum species, such as Taraxacum koksaghyz and Taraxacum brevicorniculatum, produce large amounts of high-quality natural rubber in their latex, the milky cytoplasm of specialized cells known as laticifers. This high-molecular mass biopolymer consists mainly of poly(cis-1,4-isoprene) and is deposited in rubber particles by particle-bound enzymes that carry out the stereospecific condensation of isopentenyl diphosphate units. The polymer configuration suggests that the chain-elongating enzyme (rubber transferase; EC 2.5.1.20) is a cis-prenyltransferase (CPT). Here, we present a comprehensive analysis of transgenic T. brevicorniculatum plants in which the expression of three recently isolated CPTs known to be associated with rubber particles (TbCPT1 to -3) was heavily depleted by laticifer-specific RNA interference (RNAi). Analysis of the CPT-RNAi plants by nuclear magnetic resonance, size-exclusion chromatography, and gas chromatography-mass spectrometry indicated a significant reduction in rubber biosynthesis and a corresponding 50% increase in the levels of triterpenes and the main storage carbohydrate, inulin. Transmission electron microscopy revealed that the laticifers in CPT-RNAi plants contained fewer and smaller rubber particles than wild-type laticifers. We also observed lower activity of hydroxymethylglutaryl-coenzyme A reductase, the key enzyme in the mevalonate pathway, reflecting homeostatic control of the isopentenyl diphosphate pool. To our knowledge, this is the first in planta demonstration of latex-specific CPT activity in rubber biosynthesis. © 2012 American Society of Plant Biologists.

Item Type:	Journal Article
Subjects:	Q Science > Q Science (General)
Divisions:	Faculty of Science > Life Sciences (2010- ) > Biological Sciences ( -2010)
Journal or Publication Title:	Plant Physiology
Publisher:	American Society of Plant Biologists
ISSN:	0032-0889
Date:	March 2012
Volume:	Vol.158
Number:	No.3
Page Range:	pp. 1406-1417
Identification Number:	10.1104/pp.111.187880
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access
URI:	http://wrap.warwick.ac.uk/id/eprint/44430

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