Assessment of the biogeographical variation of seed size and seed oil traits in wild Silphium integrifolium Michx. genotypes

Authors: REINERT, STEPHAN - University Of Colorado; VAN TASSEL, DAVID - The Land Institute; SCHLAUTMAN, BRANDON - The Land Institute; KANE, NOLAN - University Of Colorado; Hulke, Brent

Submitted to: Plant Genetic Resources
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/10/2019
Publication Date: 9/10/2019
Citation: Reinert, S., Van Tassel, D.L., Schlautman, B., Kane, N.C., Hulke, B.S. 2019. Assessment of the biogeographical variation of seed size and seed oil traits in wild Silphium integrifolium Michx. genotypes. Plant Genetic Resources. 17(5):427-436. https://doi.org/10.1017/S1479262119000248.
DOI: https://doi.org/10.1017/S1479262119000248

Interpretive Summary: Silphium is a close relative of sunflower with many similar characteristics and similar native range. However, it is a perennial and has not received much attention for use as a crop until very recently. In Europe, it is being used for production of biogas and other biomass derived fuels. In the US, it has received interest as an oilseed crop, like sunflower, that could be used in either the human consumption oil market or as a biofuel oil. It is extremely drought and heat resistant, and does not require replanting every year, which could provide a significant cost savings to farmers. The goal of this work was to understand how wild collections of this plant vary for important oilseed traits as a way to guide plant collection and early plant breeding activities. We found that plants collected from southwesterly locations in the native range of Silphium had larger seeds, more unsaturated fat, and less saturated fat, which are all considered positive traits. Plant breeding work should incorporate plants from this southwestern zone.

Technical Abstract: Silphium spp. have garnered interest in Europe as a bioenergy crop and in North America as a perennial oilseed crop. However, very little has been done at this early stage of domestication to characterize wild collections for many key characteristics, including important oilseed traits. The objective of this work was to develop a basic understanding of how biogeography and associated population genetic forces have shaped seed phenotypes in plant collections across the native range of Silphium integrifolium Michx., the primary domestication candidate for oilseed use. A collection of 53 accessions was grown in a common environment in Salina, KS, which is a location well within the native range of the species. Plants from each collection site were random mated by hand to produce seed representative of each accession, and the seeds subjected to seed dimensional trait, oil content, and oil composition analyses. Kernel width varied along a latitudinal cline of collection site, while kernel length varied across a longitudinal cline. Palmitic and linoleic acids were inversely correlated with each other and varied along a longitudinal cline of collection site. The results indicate that accessions collected from more southwesterly sites tended to have larger seed and those from more westerly sites had higher linoleic acid content and lower palmitic and myristic acids, which are all desirable phenotypes for an oilseed Silphium.