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First published online February 25, 2005; 10.1104/pp.104.058974 Plant Physiology 137:1037-1048 (2005) © 2005 American Society of Plant Biologists Differential Regulation of FLOWERING LOCUS C Expression by Vernalization in Cabbage and Arabidopsis1Institute of BioAgricultural Sciences, Academia Sinica, Taipei 115, Taiwan R.O.C. (S.-I.L., J.-G.W., S.-Y.P., C.-l.S., T.-J.C.); and Tainan District Agricultural Research and Extension Station, Tainan 701, Taiwan R.O.C. (S.-S.W.)
Vernalization is required to induce flowering in cabbage (Brassica oleracea var Capitata L.). Since FLOWERING LOCUS C (FLC) was identified as a major repressor of flowering in the vernalization pathway in Arabidopsis (Arabidopsis thaliana), two homologs of AtFLC, BoFLC3-2 and BoFLC4-1, were isolated from cabbage to investigate the molecular mechanism of vernalization in cabbage flowering. In addition to the sequence homology, the genomic organization of cabbage FLC is similar to that of AtFLC, except that BoFLC has a relatively smaller intron 1 compared to that of AtFLC. A vernalization-mediated decrease in FLC transcript level was correlated with an increase in FT transcript level in the apex of cabbage. This observation is in agreement with the down-regulation of FT by FLC in Arabidopsis. Yet, unlike that in Arabidopsis, the accumulation of cabbage FLC transcript decreased after cold treatment of leafy plants but not imbibed seeds, which is consistent with the promotion of cabbage flowering by vernalizing adult plants rather than seeds. To further dissect the different regulation of FLC expression between seed-vernalization-responsive species (e.g. Arabidopsis) and plant-vernalization-responsive species (e.g. cabbage), the pBoFLC4-1::BoFLC4-1::GUS construct was introduced into Arabidopsis to examine its vernalization response. Down-regulation of the BoFLC4-1::GUS construct by seed vernalization was unstable and incomplete; in addition, the expression of BoFLC4-1::GUS was not suppressed by vernalization of transgenic rosette-stage Arabidopsis plants. We propose a hypothesis to illustrate the distinct mechanism by which vernalization regulates the expression of FLC in cabbage and Arabidopsis.
1 This work was supported by grants from Academia Sinica and the National Science Council of the Republic of China (grant nos. NSC902313B001022 and NSC912313B001032 to T.-J.C.). 2 Present address: Vita Genomics, Inc., Taipei 248, Taiwan R.O.C. Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.104.058974. * Corresponding author; e-mail tjchiou{at}gate.sinica.edu.tw; fax 886226515600. Received December 26, 2004; returned for revision December 27, 2004; accepted December 27, 2004. This article has been cited by other articles:
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