Quantitative trait loci for flowering time and morphological traits in multiple populations of Brassica rapa

Abstract

Wide variation for morphological traits exists in Brassica rapa and the genetic basis of this morphological variation is largely unknown. Here is a report on quantitative trait loci (QTL) analysis of flowering time, seed and pod traits, growth-related traits, leaf morphology, and turnip formation in B. rapa using multiple populations. The populations resulted from crosses between the following accessions: Rapid cycling, Chinese cabbage, Yellow sarson, Pak choi, and a Japanese vegetable turnip variety. A total of 27 QTL affecting 20 morphological traits were detected, including eight QTL for flowering time, six for seed traits, three for growth-related traits and 10 for leaf traits. One major QTL was found for turnip formation. Principal component analysis and co-localization of QTL indicated that some loci controlling leaf and seed-related traits and those for flowering time and turnip formation might be the same. The major flowering time QTL detected in all populations on linkage group R02 co-localized with BrFLC2. One major QTL, controlling turnip formation, was also mapped at this locus. The genes that may underly this QTL and comparative analyses between the four populations and with Arabidopsis thaliana are discussed.

Genetic Dissection of Leaf Development in Brassica rapa Using a Genetical Genomics Approach

“…This indicates genotype 3 environment 3 developmental stage effects on leaf development. Several other studies also showed the impact of diverse environments on QTL detection for leaf development in Brassica species and maize (Zea mays; Lou et al, 2007;Li et al, 2009;Ku et al, 2012;Raman et al, 2013). Temporal analysis of leaf growth showed both different and common pQTLs at different growth stages, which accumulated to a large number of loci affecting leaf development ( Fig.…”

“…The genetic regulation of leaf architecture has been unraveled through quantitative trait locus (QTL) analyses in Brassica species (Lou et al, 2007;Kubo et al, 2010;Yu et al, 2013). Lan and Paterson (2001) located significant QTLs explaining 45% of the phenotypic variation in lamina length (LL), three of which colocalized with QTLs that affected leaf width (LW) in B. oleracea.…”

“…Lan and Paterson (2001) located significant QTLs explaining 45% of the phenotypic variation in lamina length (LL), three of which colocalized with QTLs that affected leaf width (LW) in B. oleracea. In another study, Lou et al (2007) detected 10 QTLs for leaf traits using three different mapping populations. By synteny analysis of QTL regions of B. rapa with the Arabidopsis genome, Li et al (2009Li et al ( , 2013 identified the leaf lobe depth and leaf hairiness genes, BRASSICA RAPA GIBBERELLIN 20-OXIDASE 3 (BrGA20OX3) AND BRASSICA RAPA GLABRA1, and Zhang et al (2009) successfully cloned a BRASSICA RAPA TRANSPARENT TESTA GLABRA1 gene controlling leaf hairiness and seed coat color.…”

Mapping QTLs for mineral accumulation and shoot dry biomass under different Zn nutritional conditions in Chinese cabbage (Brassica rapa L. ssp. pekinensis)

“…Furthermore the syntenic relationship with the related genus Arabidopsis is now well established (reviewed by Schranz et al 2006) and allows the comparison of map positions between Brassica and Arabidopsis. For B. rapa QTL analyses have been described for a wide variety of morphological and physiological traits such as seed colour, pubescence, flowering time (Teutonico and Osborn 1994;Song et al 1995;Nozaki et al 1997;Lou et al 2007), oleic acid concentration (Tanhuanpaa et al 1996), linolenic acid content (Tanhuanpaa and Schulman 2002), clubroot resistance (Suwabe et al 2006) and black rot resistance (Sogengas et al 2007). As microspore culture can be applied efficiently in Brassica species, doubled haploid (DH) populations are presently the preferred mapping populations for QTL studies because of their immortality and homozygosity which allows replicated experiments.…”

Polymorphism and Divergence at Three Duplicate Genes in Brassica nigra

“…As already stated, altered expression of AtCOL1 in transgenic plants did not affect flowering time (Ledger et al 2001). In other Brassica species such as B. oleracea, B. rapa, and B. napus, QTL studies have suggested genes other than COL1 to be the most important for flowering time variation in these species (Schranz et al 2002;Kim et al 2006;Okazaki et al 2007;Lou et al 2007). Of course, this does not rule out the involvement of AtCOL1 in other, yet undetected, functions, and the possibility that the lack of evidence on the involvement of COL1 in the control of flowering time is simply reflecting a lack of power of the QTL studies carried out in other Brassica species.…”