Abstract Detail

Genetics

Bird, Kevin [1], Baseggio, Matheus [2], Gore, Michael [2], Robertson, Larry [3], Pires, Joseph Chris [1], Labate, Joanne [3].

Population Genetics and Association Mapping of Nutritional Traits in the Vegetable Crop Brassica rapa.

Biofortification - the enhancement of crop nutritional quality through plant breeding - is potentially a sustainable and cost-effective strategy for addressing micronutrient deficiencies throughout the world. Success of biofortification depends on the identification of key genes associated with nutritional quality, followed by increasing the nutritional value of locally adapted varieties by selecting favorable alleles in breeding populations. Without connection of phenotype to genotype, biofortification will likely be ineffective for improving targeted nutritional traits. Brassica rapa L. is an agriculturally important vegetable crop, with 100 million tons harvested globally in 2012. It is a source of numerous essential mineral nutrients including - the most commonly deficient micronutrient in human populations. Plants in the Brassicaceae family also contain a unique class of sulfur-containing compounds called glucosinolates that show anti-carcinogenic activities. Successful genetic dissection of these traits requires knowledge of the genetic diversity of the species and implementation of quantitative genetic methods like genome-wide association study (GWAS). We GBS sequenced 364 accessions of Brassica rapa and grew them in an augmented block design at the USDA fields in Geneva, NY for metabolite sampling. Fresh leaf tissue was sampled for HPLC and ICP-MS analyses to measure glucosinolate and mineral nutrients, respectively. Analysis of population structure based on STRUCTURE and ADMIXTURE software suggests five to eight main subpopulation groups comprise this Brassica rapa diversity panel. Genetic diversity analyses indicate minor population differentiation between subspecies with an average Fst of 0.16, and the most genetically distal subspecies being the oilseed type yellow sarson (subsp. trilocularis). Inbreeding coefficients suggest this may be due to high outcrossing in the sampled accessions. An analysis of molecular variance (AMOVA) showed most genetic variance to be within populations (83%) compared to among populations (17%). Selective sweeps were computed by Fst outlier and composite likelihood ratio to identify loci under positive and balancing selection. The results of selective sweeps were compared to genomic regions identified via GWAS to be associated with glucosinolate and mineral content across the species. This study is one of the most comprehensive genetic diversity analyses of Brassica rapa and the first GWAS in this species.

1 - University Of Missouri, 371 Bond Life Sciences Center, 1201 Rollins Street, Columbia, MO, 65211-7310, USA
2 - Cornell University, Plant Breeding and Genetics, 310 Bradfield Hall, Ithaca, NY, 14853, USA
3 - USDA ARS, Plant Genetics Research Unit, 630 W. North Street, Geneva, NY, 14456, USA

Keywords:
population genetics
GWAS
nutrition
Brassicaceae
genetics.

Presentation Type: Oral Paper
Session: 11, Genetics
Location: 105/Savannah International Trade and Convention Center
Date: Monday, August 1st, 2016
Time: 4:15 PM
Number: 11011
Abstract ID:903
Candidate for Awards:None