Abstract
The rubber content and the activities of enzymes in the polyisoprenoid pathway in Parthenium argentatum (guayule) were examined throughout the growing season in field plots in the Chihuahuan Desert. The rubber content of the plants was low in July and August and slowly increased until October. From October to December there was a rapid increase in rubber formation (per plant) from 589.0 mg to 4438.0 mg. The percentage of rubber in the plants increased from 0.7% (mg/g dry weight) in August and 1.27% in October to 5.5% in December. The rapid increase in rubber formation may result from exposing the plants to low temperatures of 5 to 7[deg]C. The activity of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) was 21.1 nmol mevalonic acid (MVA) h-1 g-1 fresh weight in the bark of the lower stems in June during seedling growth and decreased to 5.1 nmol MVA h-1g-1 fresh weight in July and 2.9 nmol MVA h-1 g-1 fresh weight in September. From October to December, the activity increased from 5.0 to 29.9 nmol MVA h-1 g-1 fresh weight. The activity of rubber transferase was 65.5 nmol isopentenyl pyrophosphate (IPP) h-1 g-1fresh weight in the bark in September and increased to 357.5 nmol IPP h-1 g-1 fresh weight in December. The rapid increase in the activities of HMGR and rubber transferase coincided with the rapid increase in rubber formation. The activities of MVA kinase and IPP isomerase did not significantly increase in the fall and winter. A tomato HMGR-1 cDNA probe containing a highly conserved C-terminal region of HMGR genes hybridized at low stringency with several bands on blots of HindIII-digested genomic DNA from guayule. In northern blots with the HMGR-1 cDNA probe at low stringency, HMGR mRNA was high in June and November, corresponding to periods of high HMGR activity during seedling growth and rapid increase in rubber formation. The seasonal variations in rubber formation and HMGR mRNA, HMGR activity, and rubber transferase activity may be due to low temperature stimulation in the fall and winter months.
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- Caelles C., Ferrer A., Balcells L., Hegardt F. G., Boronat A. Isolation and structural characterization of a cDNA encoding Arabidopsis thaliana 3-hydroxy-3-methylglutaryl coenzyme A reductase. Plant Mol Biol. 1989 Dec;13(6):627–638. doi: 10.1007/BF00016018. [DOI] [PubMed] [Google Scholar]
- Chin D. J., Luskey K. L., Faust J. R., MacDonald R. J., Brown M. S., Goldstein J. L. Molecular cloning of 3-hydroxy-3-methylglutaryl coenzyme a reductase and evidence for regulation of its mRNA. Proc Natl Acad Sci U S A. 1982 Dec;79(24):7704–7708. doi: 10.1073/pnas.79.24.7704. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Choi D., Ward B. L., Bostock R. M. Differential induction and suppression of potato 3-hydroxy-3-methylglutaryl coenzyme A reductase genes in response to Phytophthora infestans and to its elicitor arachidonic acid. Plant Cell. 1992 Oct;4(10):1333–1344. doi: 10.1105/tpc.4.10.1333. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Goss R. A., Benedict C. R., Keithly J. H., Nessler C. L., Stipanovic R. D. cis-Polyisoprene Synthesis in Guayule Plants (Parthenium argentatum Gray) Exposed to Low, Nonfreezing Temperatures. Plant Physiol. 1984 Mar;74(3):534–537. doi: 10.1104/pp.74.3.534. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Narita J. O., Gruissem W. Tomato hydroxymethylglutaryl-CoA reductase is required early in fruit development but not during ripening. Plant Cell. 1989 Feb;1(2):181–190. doi: 10.1105/tpc.1.2.181. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Southern E. M. Detection of specific sequences among DNA fragments separated by gel electrophoresis. J Mol Biol. 1975 Nov 5;98(3):503–517. doi: 10.1016/s0022-2836(75)80083-0. [DOI] [PubMed] [Google Scholar]
- Yang Z., Park H., Lacy G. H., Cramer C. L. Differential activation of potato 3-hydroxy-3-methylglutaryl coenzyme A reductase genes by wounding and pathogen challenge. Plant Cell. 1991 Apr;3(4):397–405. doi: 10.1105/tpc.3.4.397. [DOI] [PMC free article] [PubMed] [Google Scholar]