Assessment of Genetic Diversity Based on Phenotypic Traits and Microsatellite Markers in <i>Brassica napus</i> L. Landrace in the Kanto Region, Japan (Norabona)

Abstract

Brassica napus L. is one of the most important oilseed crops in the world. The flower stalks (lateral shoots) of the leafy vegetable B. napus landrace, commonly known as norabona, are consumed for nutritional purposes and these plants are grown in the Kanto region of Japan. In the present study, we revealed the diversity of norabona at genotypic and phenotypic levels. Samples were collected from four different areas in the Kanto region of Japan and comprised other leaf vegetable landraces (kakina; B. napus and komatsuna; B. rapa). Phenotypic traits were assessed by investigating six morphological traits and five compositions for flower stalks. Principal component analysis in multivariate analysis demonstrated that the 20 norabona and kakina samples in the present study could be separated into three clusters. Genotyping using a total of 24 simple sequence repeat markers and Nei's matrix genetic distances and neighbor-joining clustering method led to the partitioning of 23 samples into three groups and komatsuna. The genotypic Group 1b comprised the largest number of norabona samples; the farthest geographic distance was observed in genetically close pairs. On the basis of our results, we concluded that (1) the norabona population in Japan is phenotypically diverse and that (2) this population is not genetically identical, but consists of different genotype subpopulations that are geographically not divergent.

Identification of SSR Markers Associated with Yield-Related Traits and Heterosis Effect in Winter Oilseed Rape (Brassica Napus L.)

“…Chen et al [19] obtained, in their study, lower PIC values (from 0.16 to 0.59) using 30 microsatellite markers to test 537 individuals of feral B. napus. In Raza et al [18]'s study, polymorphic information content was also lower and varied from 0.37 to 0.71, with an average of 0.66 per primer, while in Tsuge et al [17]'s study it ranged from 0.04 to 0.68 with an average of 0.36 for 24 markers tested on 22 Brassica genotypes.…”

“…To test parental lines of studied populations, 89 SSR primer pairs were used. Some of these primers were also tested in rapeseed genetic diversity studies [17,19,46,47]. After initial analysis, 43 markers proved to be polymorphic and were used to analyze all genotypes.…”

“…Therefore, the evaluation of microsatellites and the assignment of alleles to specific loci can be difficult in Brassica napus [15]. Nevertheless, these markers are frequently chosen for various rapeseed research, e.g., genetic diversity [16][17][18][19], map construction, and identification of quantitative trait loci (QTL) [20][21][22], or investigating the heterosis effect [23,24]. Hence, we decided that these markers are suitable for our research.…”