Phylogenetic relationships among cultivated types of Brassica rapa L. em. Metzg. as revealed by AFLP analysis

Abstract

The cultivated types of Brassica rapa L. em. Metzg. consist of morphologically distinct subspecies such as turnip, turnip rape, Chinese cabbage, pak choi and pot herb mustard which are classified as ssp. rapa, ssp. oleifera, ssp. pekinensis, ssp. chinensis and ssp. nipposinica (syn. ssp. japonica), respectively. We attempted to elucidate the phylogenetic relationships among the cultivated types of B. rapa. Thirty-two accessions from the Eurasian Continent were analyzed using AFLP markers with a cultivar of B. oleracea as an outgroup. In total, 455 bands were detected in the ingroup and 392 (86.6%) were polymorphic. The Neighbor-Joining tree based on the AFLP markers indicated that the accessions of B. rapa were congregated into two groups according to geographic origin. One group consisted of ssp. rapa and ssp. oleifera of Europe and Central Asia and the other included all the subspecies of East Asia. Our results suggest that cultivars from East Asia were probably derived from a primitive cultivated type, which originated in Europe or in Central Asia and migrated to East Asia. This primitive cultivated type was probably a common ancestor of ssp. rapa and ssp. oleifera. The Neighbor-Joining tree also shows that leafy vegetables in East Asia such as ssp. pekinensis, ssp. chinensis and ssp. nipposinica were differentiated several times from the distinct cultivars of ssp. oleifera in East Asia.

Mapping QTLs for root morphological traits inBrassica rapa L. based on AFLP and RAPD markers

“…Very little is known about the genetic control of the development of storage roots. Considering the great variability of storage roots identified in Brassica rapa (Takuno et al 2007), a polygenic character of the root traits was expected. In the present study, a total of 18 QTLs with different effects on 3 root morphological traits were detected by using an F 2 : F 3 population derived from a cross between Chinese cabbage and turnip.…”

Analysis ofPolA1intron 19 and Ntag sequences reveals two ancestral lineages in the origin of theBrassica rapacomplex and Chinese cabbage (B. rapavar.pekinensis)

“…Although phylogenetic analysis using DNA markers had suggested the presence of two major clusters in B. rapa (Song et al, 1988;Guo et al, 2014;He et al, 2003;Zhao et al, 2005;Takuno et al, 2007), no sequence specific to each cluster had yet been identified. In fact, we had sequenced two single-copy nuclear genes, Elongation Factor G and Disrupted Mitotic cDNA 1, which were preferred for use in phylogenetic analysis (Petersen et al, 2006).…”

“…Because B. rapa has a genotypic self-incompatibility system, complex hybridisations among different cultivar groups have occurred to create a wide range of morphotypes; therefore, it is difficult to trace phylogenetic lineages. Although phylogenetic analysis using molecular markers such as Restriction Fragment Length Polymorphisms (RFLPs), Random Amplified Polymorphic DNAs (RAPDs), and Amplified Fragment Length Polymorphisms (AFLPs), have divided most cultivars of B. rapa into two major clusters (Song et al, 1988;Guo et al, 2014;He et al, 2003;Zhao et al, 2005;Takuno et al, 2007), detailed relationships among the different morphotypes and cultivar groups remain to be understood.…”

Differential Effect of Day and Night Temperature Regimes on the Growth and Biochemical Attributes of Violet Rape (Brassica campestris ssp. chinensis L.)

“…As compared to other family members, it doesn't have a well-developed root system, producing sessile leave with a short stem. Due to high water and fertile soil requirements, this plant cannot tolerate water for longer periods [12][13]. Previous studies have shown that temperature for violet rape seed germination ranges 4-40ºC, but the most suited temperature lies between 20 and 25ºC, in which it grows optimally.…”