Genetic diversity evaluation of rapeseed genotypes (Brassica napus L.) based on phenotypic traits and random amplified polymorphic DNA (RAPD) markers
Oilseed is the most important source of vegetable oil and the basis of breeding strategies is genetic diversity assessment. Genetic diversity of 19 rapeseed genotypes as well as their ancient ancestors Brassica rapa L. and Brassica oleracea L. were assessed using random amplified polymorphic DNA (RAPD) primers and morpho-phenological traits. Path analysis showed that number of pods per main branch had the highest direct effect on seed yield. Stepwise regressing showed numbers of pods per main branch was entered as the first variable in the model and explained 79% of seed yield variation. Phenotypic cluster showed that genotypes were divided into 4 groups. Polymorphic RAPD primers produced 74 bands. The range of PIC value for the used primer was 0.35 to 2.78. Result indicates primer D as the best primer for genetic diversity analysis. Molecular similarity matrix showed that Magnum and Hyola308 had the highest similarity. Molecular cluster had divided the genotypes into 3 groups; early maturing and high yielding cultivars were located in the first group, genotypes with high number of seed per pod and seed yield were located in the second group, while genotypes at third group had lowest number of pods per main branch and number of seed per pod. Obtained biplot from two first principal component analysis (PCA) showed that number of pod per main branch has an important role on seed yield, and this can be mentioned as an important trait for breeding programs.
Key words: Genetic diversity, path analysis, RAPD marker, rapeseed.