Genetic Diversity, Population Structure and Linkage Disequilibrium in Brassica napus l. Germplasm and Its Implication for Association Mapping

Rapeseed/Canola (Brassica napus L., AACC, n=19), is an amphidiploid that originated from a natural cross between two diploid species about 7500 years ago by natural hybridization, followed by chromosome doubling. It is one of the most important oilseed crops cultivated in many parts of the world. It ranks as the world's second largest oilseed producing crop next to soybean. Global demand of vegetable oils is increasing rapidly, and the present production is unable to meet the required demand. North Dakota is the leader in canola acreage and production with over 83% of U.S. acreage and produces about 84% of all U.S. canola (1.02 million acres and 1.7 billion pounds with a value of $364 million – 5 yr. average from 2009-2013; USDA-NASS). Studies that describe the genetic variation in canola populations are limited in U.S. With this, we used 367 canola germplasm consisting of spring-, winter-, and semi-winter-type from the world collection from 27 countries to understand the population structure and linkage disequilibrium that has implications for association mapping. The individual germplasm were sequenced using GBS pipeline. The reads were mapped to the whole genome and 42,575 high quality SNPs were used further to understand the diversity and population structure.