Integrative Plant Physiology
Kim, Sang Yeol , Michaels, Scott D. .
The effect of low red/far-red ratio on flowering.
The transcription factor CONSTANS (CO) plays a key role in the promotion of flowering by day length. CO transcription is regulated by the circadian clock, such that transcription peaks late in the day in long days and after dark in short days. Because the CO protein is degraded in darkness, CO protein only accumulates under LD. CO promotes flowering by activating the expression of downstream floral promoters such as FT and SOC1. Naturally occurring winter annual accessions of Arabidopsis flowering are late flowering unless flowering is promoted by a long period of cold exposure (vernalization). In these strains the floral inhibitor FLOWERING LOCUS C (FLC) acts to repress the expression of FT and SOC; vernalization promotes flowering through a permanent epigenetic suppression of FLC expression. Plants have evolved mechanisms that enable them to respond to the various light conditions. It is well known that shade-avoiding plants sense the low red/far-red ratio and react with hypocotyl, petiol elongation and early flowering. The low red/far-red mechanism for flowering, however, is not established well. The late flowering phenotype of Col FRI (winter annual accession) is partially suppressed by low red/far-red ratio. FLC transcripts, however, are not changed and FT transcripts are increased. It suggests that autonomous pathway still suppress flowering by FLC but some other pathway that is activated by low red/far-red ratio overcome it to induce flowering. Thus, we investigated the effect of low red/far-red in various backgrounds and found that co and gi showed less sensitive against low red/far-red ratio. It suggests that CO and GI mediate the effect of low red/far-red ratio. In addition, we found that GA (Gibberlin) is also main factor to perceive low red/far-red ratio. In summary, we revealed that CO, GI and GA are central factors to mediate low red/far-red light signaling for flowering.
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1 - Indiana University, Plant Biology, 915 East Third st. Myers Hall 330, Bloomington, IN, 47405, US
2 - Indiana University, Plant Biology
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM