Genetic dissection of root architectural traits by QTL and genome‐wide association mapping in rapeseed (Brassica napus).

Variation in root architecture is essential for the adaptation of plants to target environments. A non‐destructive gel‐based mini‐rhizotron system was used for root architecture trait phenotyping. This system has facilitated the visualization of root architectural traits in large genotype collection of rapeseed including 94 double haploid (DH) lines from "Express617" x "V8" and 439 inbred lines (ASSYST diversity set). A high‐density Express617‐V8 linkage map was used for quantitative trait loci (QTLs) identification in DH population based on standard composite interval mapping. 6K SNPs were analysed for association mapping of root traits in ASSYST diversity set. A large variation, broad segregation and medium–low heritability of root architectural traits, primary root length and growth rate, lateral root number, lateral root length and lateral root density, were observed. In the double haploid population, 11 QTL regions, and in the diversity set, 38 significant marker–trait associations were detected. Significant marker–trait associations proved that these are quantitatively inherited traits controlled by multiple genes which revealed to proceed for genetic improvement and selection of rapeseed lines with improved root system. [ABSTRACT FROM AUTHOR]