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- Title
Nonadditive Regulation of FRI and FLC Loci Mediates flowering-Time Variation in Arabidopsis Allopolyploids.
- Authors
Jianlin Wang; Lu Tian; Hyeon-Se Lee; Z. Jeffrey Chen
- Abstract
Allopolyploidy is formed by combining two or more divergent genomes and occurs throughout the evolutionary history of many plants and some animals. Transcriptome analysis indicates that many genes in various biological pathways, including flowering time, are expressed nonadditively (different from the midparent value). However, the mechanisms for nonadditive gene regulation in a biological pathway are unknown. Natural variation of flowering time is largely controlled by two epistatically acting loci, namely FRIGIDA (FRI) and FLOWERING LOCUS C (FLC). FRl upregulates FLC expression that represses flowering in Arabidopsis. Synthetic Arabidopsis allotetraploids contain two sets of FLC and FRI genes originating from Arabidopsis thaliana and A. arenosa, respectively, and flower late. Inhibition of early flowering is caused by upregulation of A. thaliana FLC (AtFLC) that is trans-activated by A. arenosa FRI (AaFRI). Two duplicate FLCs (AaFLC1 and AaFLC2) originating from A. arenosa are expressed in some allotetraploids but silenced in other lines. The expression variation in the allotetraploids is associated with deletions in the promoter regions and first introns of A. arenosa FLCs. The strong AtFLC and AaFLC loci are maintained in natural Arahidopsis allotetraploids, leading to extremely late flowering. Furthermore, FLC expression correlates positively with histone H3-Lys4 rnethylation and H3-Lys9 acetylation and negatively with H3-Lys9 niethylation, epigenetic marks for gene activation and silencing. We provide evidence for interactive roles of regulatory sequence changes, chromatin modification, and trans-acting effects in natural selection of orthologous FLC loci, which determines the fate of duplicate genes and adaptation of allopolyploids during evolution.
- Subjects
POLYPLOIDY; PLANT genomes; FLOWERING time; GENETIC regulation; ARABIDOPSIS; PLANT gene silencing; PLANT genetics
- Publication
Genetics, 2006, Vol 173, Issue 2, p965
- ISSN
0016-6731
- Publication type
Article
- DOI
10.1534/genetics.106.056580