ALBERT

Description: Teosinte ( Zea mays ssp. parviglumis ) is the wild ancestor of modern maize ( Zea mays ssp. mays ). Teosinte contains greater genetic diversity compared with maize inbreds and landraces, but its use is limited by insufficient genetic resources to evaluate its value. A population of teosinte near isogenic lines (NILs) was previously developed to broaden the resources for genetic diversity of maize, and to discover novel alleles for agronomic and domestication traits. The 961 teosinte NILs were developed by backcrossing 10 geographically diverse parviglumis accessions into the B73 (reference genome inbred) background. The NILs were grown in two replications in 2009 and 2010 in Columbia, MO and Aurora, NY, respectively, and near infrared reflectance spectroscopy and nuclear magnetic resonance calibrations were developed and used to rapidly predict total kernel starch, protein, and oil content on a dry matter basis in bulk whole grains of teosinte NILs. Our joint-linkage quantitative trait locus (QTL) mapping analysis identified two starch, three protein, and six oil QTL, which collectively explained 18, 23, and 45% of the total variation, respectively. A range of strong additive allelic effects for kernel starch, protein, and oil content were identified relative to the B73 allele. Our results support our hypothesis that teosinte harbors stronger alleles for kernel composition traits than maize, and that teosinte can be exploited for the improvement of kernel composition traits in modern maize germplasm.

Description: During ongoing proteomic analysis of the soybean ( Glycine max (L.) Merr) germplasm collection, PI 603408 was identified as a landrace whose seeds lack accumulation of one of the major seed storage glycinin protein subunits. Whole genomic resequencing was used to identify a two-base deletion affecting glycinin 5 . The newly discovered deletion was confirmed to be causative through immunological, genetic, and proteomic analysis, and no significant differences in total seed protein content were found to be due to the glycinin 5 loss-of-function mutation per se . In addition to focused studies on this one specific glycinin subunit-encoding gene, a total of 1,858,185 nucleotide variants were identified, of which 39,344 were predicted to affect protein coding regions. In order to semiautomate analysis of a large number of soybean gene variants, a new SIFT 4G (Sorting Intolerant From Tolerated 4 Genomes) database was designed to predict the impact of nonsynonymous single nucleotide soybean gene variants, potentially enabling more rapid analysis of soybean resequencing data in the future.

Description: Soybean oil is highly unsaturated but oxidatively unstable, rendering it nonideal for food applications. Until recently, the majority of soybean oil underwent partial chemical hydrogenation, which produces trans fats as an unavoidable consequence. Dietary intake of trans fats and most saturated fats are conclusively linked to negative impacts on cholesterol levels and cardiovascular health. Two major soybean oil breeding targets are: (1) to reduce or eliminate the need for chemical hydrogenation, and (2) to replace the functional properties of partially hydrogenated soybean oil. One potential solution is the elevation of seed stearic acid, a saturated fat which has no negative impacts on cardiovascular health, from 3 to 4% in typical cultivars to 〉 20% of the seed oil. We performed QTL analysis of a population developed by crossing two mutant lines, one with a missense mutation affecting a stearoyl-acyl-carrier protein desaturase gene resulting in ~11% seed stearic acid crossed to another mutant, A6, which has 24–28% seed stearic acid. Genotyping-by-sequencing (GBS)-based QTL mapping identified 21 minor and major effect QTL for six seed oil related traits and plant height. The inheritance of a large genomic deletion affecting chromosome 14 is the basis for largest effect QTL, resulting in ~18% seed stearic acid. This deletion contains SACPD-C and another gene(s); loss of both genes boosts seed stearic acid levels to ≥ 18%. Unfortunately, this genomic deletion has been shown in previous studies to be inextricably correlated with reduced seed yield. Our results will help inform and guide ongoing breeding efforts to improve soybean oil oxidative stability.