The Brassica rapa FLC homologue FLC2 is a key regulator of flowering time, identified through transcriptional co-expression networks.
The role of many genes and interactions among genes involved in flowering time have been studied extensively in Arabidopsis, and the purpose of this study was to investigate how effectively results obtained with the model species Arabidopsis can be applied to the Brassicacea with often larger and more complex genomes. Brassica rapa represents a very close relative, with its triplicated genome, with subgenomes having evolved by genome fractionation. The question of whether this genome fractionation is a random process, or whether specific genes are preferentially retained, such as flowering time (Ft) genes that play a role in the extreme morphological variation within the B. rapa species (displayed by the diverse morphotypes), is addressed. Data are presented showing that indeed Ft genes are preferentially retained, so the next intriguing question is whether these different orthologues of Arabidopsis Ft genes play similar roles compared with Arabidopsis, and what is the role of these different orthologues in B. rapa. Using a genetical-genomics approach, co-location of flowering quantitative trait loci (QTLs) and expression QTLs (eQTLs) resulted in identification of candidate genes for flowering QTLs and visualization of co-expression networks of Ft genes and flowering time. A major flowering QTL on A02 at the BrFLC2 locus co-localized with cis eQTLs for BrFLC2, BrSSR1, and BrTCP11, and trans eQTLs for the photoperiod gene BrCO and two paralogues of the floral integrator genes BrSOC1 and BrFT. It is concluded that the BrFLC2 Ft gene is a major regulator of flowering time in the studied doubled haploid population.
Wageningen UR Plant Breeding, PO Box 386, AJ 6700 Wageningen, The Netherlands.
Dong
D
Xiao
Jian J
JJ
Zhao
Xi L
XL
Hou
Ram K
RK
Basnet
Dunia P D
DP
Carpio
Ning W
NW
Zhang
Johan
J
Bucher
Ke
K
Lin
Feng
F
Cheng
Xiao W
XW
Wang
Guusje
G
Bonnema
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029741:Brassica rapa / Q000235:genetics* / Q000502:physiology*; D002874:Chromosome Mapping; D035264:Flowers / Q000235:genetics* / Q000502:physiology*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D053263:Gene Regulatory Networks / Q000235:genetics*; D020131:Genes, Duplicate / Q000235:genetics; D017343:Genes, Plant / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D040641:Quantitative Trait Loci / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013997:Time Factors
D010940:Plant Proteins
Brassica rapa; FLOWERING LOCUS C (FLC).; candidate gene mapping; expression quantitative trait loci (eQTL); flowering time; gene expression networks; genome triplication.