Biological feedstock development as part of the domestication and commercialization of Taraxacum kok-saghyz, a potential domestic source of natural rubber and inulin: progress and outlook

摘要

The Ohio BioProducts Innovation Center (OBIC) and its private- and public-sector collaborators employ a market-pull approach to accelerate the commercialization of renewable specialty chemicals, polymers/plastics and advanced materials. Taraxacum kok-saghyz (TKS) roots contain high levels of inulin and high quality natural rubber but TKS is currently undomesticated. Since 2006, a private-public, multi-institution, multi-disciplinary team, formally recognized as the Prograr of Excellence in Natural Rubber Alternatives (PENRA), has worked to position TKS as a sustainable, domestic source of natural rubber and inulin. The team has addressed each step in the emerging TKS value chain by developing a TKS breeding program, improving existing TKS root processing methods, and securing modern evidence of the quality of TXS-derived natural rubber. TKS germplasm enhancement activities at The Ohio State University - Ohio Agricultural Research and Development Center (OSU-OARDC) is the subject of this report. Root processing and rubber qualification efforts are summarized elsewhere. Wild-collected F0 seed was found to contain a mixture of Taraxacum species (i.e., highly variable seedling phenotypes), a likely drag on TKS germplasm enhancement. Also, roots of unselected, wild-collected Taraxacum genotypes were found to contain, on average, 1.4 and 56.4 percent rubber and inulin, respectively, with rubber leve below commercialization thresholds. Foliar and floral criteria for differentiating T kok-saghyz fron other Taraxacum species were then developed along with protocols for measuring and assessing ro rubber and inulin levels. And, selected genotypes were employed in breeding activities. Rogumg non-7X5 individuals from groups of F0 seedlings increased average rubber recovery to 7.9% by ro dry weight, although recovery exceeded 10% (commercialization threshold) in 29% and 20% in. 0.3% of the F0 individuals tested. Based on phenotype and root rubber recovery, 352 F0 individual were selected as members of the base breeding population, with rubber production potential measured or estimated in 184 of these 352 F0 individuals. All members of the base breeding population and approximately five-thousand Fl individuals have been employed in controlled and uncontrolled pollination events within open, reciprocal, self, and/or diallel crossing schemes executed in greenhouse, field and high tunnel settings. In addition, 4,600 clones representing fifty-one genotypes have been produced via vegetative propagation. To date, approximately 2.7 million (1.8 kg) viable Fl and F2 TKS seed of varying pedigree have been collected, a 36-fold increase in the overall number of viable TKS seed available at project initiation in 2006. Nearly 92% of ^twelv thousand current Fl seedlings and all nascent Fl and F2 individuals await evaluation of rubber production potential; in this regard, it is worth noting that roots of approximately 2-5°/oo°f unimproved, wild-collected TKS genotypes have contained rubber levels exceeding 15% by dry weight.