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United States Department of Agriculture

Agricultural Research Service

Research Project: Improvement and Utilization of Natural Rubber- and Castor Oil-producing Industrial Crops

Location: Crop Improvement & Utilization Research

Title: Phenotype analysis of Russian dandelion root tissues from the national plant germplasm system collection

Authors
item Rawlins Jr, Lawrence
item McMahan, Colleen
item Hellier, Barbara

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: September 17, 2012
Publication Date: N/A

Technical Abstract: Russian dandelion (Taraxacum kok-saghyz) (TKS) produces high quality natural rubber (NR), cis-1,4 polyisoprene, by biosynthesis, and has been used historically as a source of NR during times of short supply or high prices for Hevea NR. The rubber is primarily located in root tissues along with appreciable levels of inulin, a storage carbohydrate used in foods and as a source of carbon for biobased products. Along with other temperate NR producing crops, such as guayule, TKS can be used for domestic production of natural rubber and inulin as a source of biobased raw materials for replacement of petroleum-based polymers and fuels. In order to facilitate development of TKS in the USA, a National Plant Germplasm System (NPGS)-sponsored collection expedition took place in 2008. Twenty accessions were collected and subsequently planted at the Western Regional Plant Introduction Station in Pullman, WA for evaluation. The objective of this study was to quantify the plant phenotypes of the new NPGS collection in terms of plant biomass, root morphology, and amount of rubber and inulin stored in the root tissue. Russian dandelion roots were harvested in October 2010 from plants approximately 1.5 years old grown from original seed and root pieces and shipped to the Western Regional Research Center in Albany, CA for testing. Roots were air dried and stored at -20°C until processing. Roots were categorized as tap, lateral, or a combination. A break test was conducted to give a visual score of the quantity of rubber in the root. Fructan content was measured using Megazyme Fructan Assay Kit, AOAC Method 999.03 and AACC Method 32.32. Rubber content was determined using Accelerated Solvent Extraction (ASE), with cyclohexane solvent at 100°C. The NR content of the roots varied from 5-19% as determined by ASE. Comparison of the break test measurements with ASE results indicated the break test was capable of distinguishing high and low rubber producers. The inulin content varied from 13-46%. No correlation was found between NR or inulin content and root morphology nor whether plants were grown from seeds vs. roots pieces. Moreover, the amount of rubber stored in the root was independent of the inulin content. With additional data collected from 2011 and 2012 root harvests, which will help to better characterize the accessions phenotypes, the next steps include correlation of plant phenotype to genotypes, and development of molecular markers for breeding lines.

Last Modified: 4/18/2014
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