Enhancement of total lipid production in vegetative tissues of alfalfa and sainfoin using chemical mutagenesis

Alfalfa (Medicago sativa L.) and sainfoin (Onobrychis viciifoila Scop.) are two key forage legumes for the western Canadian cattle industry. Despite the high protein content, drawbacks to their use exists, including inefficient protein digestibility and energy use efficiency in the ruminant system leading to economic losses and negative environmental impacts. Increasing the proportion of lipids in the diet of cattle is known to mitigate greenhouse gas emissions; however, the above two forage legumes possess only trace quantities of lipids in the shoot tissues used by the ruminants. In the current study, chemical mutagenesis was used as a conventional breeding approach to enhance lipid levels in the vegetative tissues of alfalfa and sainfoin. The mutagenesis procedures for these two forages need to be firmly established. We developed protocols for ethyl methanesulfonate (EMS)‐mediated mutagenesis by optimizing mutagen concentration and seed soaking duration. EMS‐treated populations were assessed for morphological variants and total shoot lipid content (TSLC). Fatty acid composition was examined in a subset of plants with increased TSLC. Within 24 months, the screening process identified mutagenized plants with significant increases in TSLC (3 ‐ 5% on a dry weight basis) and a subset of these also displayed alterations in fatty acid composition in both species. These genotypes provide a novel source of germplasm for the future improvement of these two forage species.