Abstract
BackgroundDeciphering the genetic architecture of a species is a good way to understand its evolutionary history, but also to tailor its profile for breeding elite cultivars with desirable traits. Aligning QTLs from diverse population in one map and utilizing it for comparison, but also as a basis for multiple analyses assure a stronger evidence to understand the genetic system related to a given phenotype.ResultsIn this study, 439 genes involved in fatty acid (FA) and triacylglycerol (TAG) biosyntheses were identified in Brassica napus. B. napus genome showed mixed gene loss and insertion compared to B. rapa and B. oleracea, and C genome had more inserted genes. Identified QTLs for oil (OC-QTLs) and fatty acids (FA-QTLs) from nine reported populations were projected on the physical map of the reference genome “Darmor-bzh” to generate a map. Thus, 335 FA-QTLs and OC-QTLs could be highlighted and 82 QTLs were overlapping. Chromosome C3 contained 22 overlapping QTLs with all trait studied except for C18:3. In total, 218 candidate genes which were potentially involved in FA and TAG were identified in 162 QTLs confidence intervals and some of them might affect many traits. Also, 76 among these candidate genes were found inside 57 overlapping QTLs, and candidate genes for oil content were in majority (61/76 genes). Then, sixteen genes were found in overlapping QTLs involving three populations, and the remaining 60 genes were found in overlapping QTLs of two populations. Interaction network and pathway analysis of these candidate genes indicated ten genes that might have strong influence over the other genes that control fatty acids and oil formation.ConclusionThe present results provided new information for genetic basis of FA and TAG formation in B. napus. A map including QTLs from numerous populations was built, which could serve as reference to study the genome profile of B. napus, and new potential genes emerged which might affect seed oil. New useful tracks were showed for the selection of population or/and selection of interesting genes for breeding improvement purpose.
Highlights
Deciphering the genetic architecture of a species is a good way to understand its evolutionary history, and to tailor its profile for breeding elite cultivars with desirable traits
439 genes related to fatty acid (FA) and TAG biosyntheses were identified in the genome of B. napus, they were homologous to 110, 224 and 173 genes from A. thaliana, B. rapa and B. oleracea, respectively
B. rapa, B. oleracea and B. napus are illustrated on Fig. 1, it was found that genes were mostly located on A3 and C3 chromosomes
Summary
Deciphering the genetic architecture of a species is a good way to understand its evolutionary history, and to tailor its profile for breeding elite cultivars with desirable traits. Long years of evolution and artificial selection have made the An and Cn genomes of B. napus somewhat different from the Ar genome of B. rapa and the Co genome of B. oleracea [10]. In the evolution history of Brassicaceae family, Brassica species underwent a whole genome triplication event compared to A. thaliana, which promoted their speciation, and that event was followed by genome duplication and rearrangement events [13,14,15,16]. Great opportunities are opened to undertake multiple important studies for further exploitation or improvement of this crop with the release of B. napus genome sequence in 2014 [19]. The distribution of all genes involved in oil formation in B. napus was not reported before
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