Mining seed quality traits in the USDA sesame germplasm collection identifies useful accessions for improving nutritional breeding

Abstract

Plant germplasm is the most basic genetic resource for plant cultivar improvement and development. Mining germplasm collections can identify accessions that are advantageous for breeding programs. To identify sesame accessions with desirable seed nutritional quality traits, the entire USDA sesame collection (1231 accessions) was screened for seed oil content, fatty acid composition, and 100-seed weight. We identified significant variability in 100-seed weight (mean: 0.32 g, range: 0.1–0.5 g) and oil content (mean: 54.9%, range 28.3%–65.5%) among the accessions. Sesame seeds mainly contained four major fatty acids: 44.8% linoleic acid (18:2), 39.5% oleic acid (18:1), 9.0% palmitic acid (16:0), 5.2% stearic acid (18:0) and six minor fatty acids: 0.1% palmitoleic acid (16:1), 0.4% linolenic acid (18:3), 0.6% arachidic acid (20:0), 0.2% gadoleic (20:1), 0.1% behenic acid (22:0), and 0.1% lignoceric acid (24:0). For each trait, two accessions were classified as having high 100-seed weight (PI 238992: 0.54 g and PI 250626: 050 g), high oil content (PI 238992: 65.5% and PI 250626: 64.2%), or high oleic acid levels (PI 263470: 54.4% and PI 263454: 50.3%). For most accessions, levels of oleic and linoleic acid were related to country origins where the germplasm accessions were collected. The information on these seed nutritional quality traits is useful, but breeding efforts or genetic methods are needed for developing new sesame cultivars or enhanced germplasm with these traits. Among 1231 accessions, nine accessions were further evaluated for additional seed nutritional quality traits and accession PI 263470 was successfully used as starting genetic material for mutagenesis to enhance levels of oleic acid.