Characterization of polyphenolic metabolites in the seeds of Vitis germplasm.

The composition and content of polyphenols in the seeds of 91 grape accessions from 17 Vitis species were characterized. Eleven compounds, including 2 gallic derivatives, 3 monomeric flavan-3-ols, 3 flavonols, resveratrol, and procyanidin B1 and B2, were identified via HPLC-MS and quantified by HPLC-DAD. In addition, seventeen dimeric and trimeric flavan-3-ols were also quantified. Tremendous variation was observed both among and within species for these compounds. Monomeric flavan-3-ols were the most abundant polyphenols in seeds, followed by dimeric and trimeric flavan-3-ols, which collectively accounted for more than 96% of the total polyphenols. V. palmata, V. vinifera, and V. vulpina had significantly higher content of total polyphenols than other species. A number of Vitis accessions with high content of various types of seed polyphenols were identified, and they can serve as potential germplasm for improving the composition and content of seed polyphenols in cultivated grapes.

A phenylalanine in DGAT is a key determinant of oil content and composition in maize.

Plant oil is an important renewable resource for biodiesel production and for dietary consumption by humans and livestock. Through genetic mapping of the oil trait in plants, studies have reported multiple quantitative trait loci (QTLs) with small effects, but the molecular basis of oil QTLs remains largely unknown. Here we show that a high-oil QTL (qHO6) affecting maize seed oil and oleic-acid contents encodes an acyl-CoA:diacylglycerol acyltransferase (DGAT1-2), which catalyzes the final step of oil synthesis. We further show that a phenylalanine insertion in DGAT1-2 at position 469 (F469) is responsible for the increased oil and oleic-acid contents. The DGAT1-2 allele with F469 is ancestral, whereas the allele without F469 is a more recent mutant selected by domestication or breeding. Ectopic expression of the high-oil DGAT1-2 allele increases oil and oleic-acid contents by up to 41% and 107%, respectively. This work provides insights into the molecular basis of natural variation of oil and oleic-acid contents in plants and highlights DGAT as a promising target for increasing oil and oleic-acid contents in other crops.