Detection and resolution of genetic loci affecting circadian period in Brassica oleracea
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Circadian rhythms regulate many aspects of plant growth, fitness and vigour. The components and detailed mechanism of circadian regulation to date have been dissected in the reference species Arabidopsis thaliana. To determine the genetic basis and range of natural allelic variation for intrinsic circadian period in the closest crop relatives, we used an accurate and high throughput data capture system to record rhythmic cotyledon movement in two immortal segregating populations of Brassica oleracea, derived from parent lines representing different crop types. Periods varied between 24.4 and 26.1 h between the parent lines, with transgressive segregation between extreme recombinant lines in both populations of ∼3.5 h. The additive effect of individual QTL identified in each population varied from 0.17 to 0.36 h. QTL detected in one doubled haploid population were verified and the mapping intervals further resolved by determining circadian period in genomic substitution lines derived from the parental lines. Comparative genomic analysis based on collinearity between Brassica and Arabidopsis also allowed identification of candidate orthologous genes known to regulate period in Arabidopsis, that may account for the additive circadian effects of specific QTL. The distinct QTL positions detected in the two populations, and the extent of transgressive segregation suggest that there is likely to be considerable scope for modulating the range of available circadian periods in natural populations and crop species of Brassica. This may provide adaptive advantage for optimising growth and development in different latitudes, seasons or climate conditions.
This work was funded by the UK Biotechnology and Biological Sciences Research Council (BBSRC). We are grateful to Dr. G.R. Teakle for provision of the reference integrated linkage map.
- Dunlap JC, Loros J, DeCoursey P (2003) Chronobiology: biological timekeeping, Sinauer Associates, SunderlandGoogle Scholar
- Engelmann W, Simon K, Phen CJ (1992) Leaf movement rhythm in Arabidopsis thaliana. Zeitschrift fur Naturforschung 47c:925–928Google Scholar
- Massie IH (1998) Patterns of variation in the Italian landrace cauliflower and broccoli. PhD Thesis, University of London, LondonGoogle Scholar
- Payne RW, Lane P, Digby P, Harding S, Leech P, Morgan G, Todd A, Thompson R, Tunnicliffe W, Welham S, White R (1993) Genstat 5 release 3 reference manual. Oxford University Press, OxfordGoogle Scholar
- Van Ooijen JW, Voorrips RE (2001) JoinMap® Version 3.0, Software for the calculation of genetic linkage map. Plant Research International, WageningenGoogle Scholar
- Yano M, Katayose Y, Ashikari M, Yamanouchi U, Monna L, Fuse T, Baba T, Yamamoto K, Umehara Y, Nagamura Y, Sasaki T (2000) Hd1, a major photoperiod sensitivity quantitative trait locus in rice, is closely related to the Arabidopsis flowering time gene CONSTANS. Plant Cell 12:2473–2483PubMedCrossRefGoogle Scholar