Fatty Acid, Flavonol, and Mineral Composition Variability among Seven Macrotyloma uniflorum (Lam.) Verdc. Accessions

Abstract: Horse gram [Macrotyloma uniflorum (Lam.) Verdc.] seeds containing high concentrations of fatty acids, flavonols and minerals should provide government, public and private organizations with a nutritious and healthy food for use by malnourished and food deprived people worldwide. Seeds from seven horse gram accessions, geographically adapted to Griffin, GA, USA were analyzed for fatty acid, flavonol, and mineral concentrations using gas chromatography, reverse-phase high performance liquid chromatography, and inductively coupled plasma-optical emission spectroscopy, respectively. Significant year effects occurred for stearic, oleic, linoleic, arachidic, gadoleic, and lignoceric acids. Oleic, linoleic, and linolenic acid ranged from 8.9%–16.8%, 40.3%–45.6%, and 11.6%–14.3%, respectively, as percent of total fatty acids measured (total oil ranged from 2.32% to 2.87%). Seed concentrations of myricetin, quercetin, and kaempferol ranged from 0–36 μg/g DW, 0–27 μg/g DW, and 240–316 μg/g DW, respectively and the only year effect was observed for kaempferol among the horse gram accessions. Year effects were found for Fe, K, Mg, Mn, Ni, and S. Mean concentrations of macrominerals (Ca, K, Mg, P, and S) and microminerals (Cu, Fe, Mn, Ni, and Zn) ranged from 1.3–14 mg/g DW, and 1.0–95.0 μg/g DW, respectively. Several correlations were observed among several fatty acids, flavonols, and minerals. The mono-unsaturated fatty acid, oleic acid correlated significantly with linoleic acid (r = −0.64), arachidic acid (r = −0.61), Ca (r = 0.50) and Zn (r = 0.51, all at P < 0.01). The flavonol, myricetin correlated significantly with quercetin (r = 0.92, P < 0.0001), while quercetin correlated with Ca (r = 0.82, P < 0.0001) and kaempferol correlated with Mg (r = 0.61, P < 0.01). Several mineral correlations were found including Fe with K (r = 0.66) and Mg (r = 0.56, both at P < 0.01). These seven horse gram accessions can be used in breeding programs to facilitate the production of superior cultivars with favorable fatty acid profiles, flavonol content, and mineral compositions.