Location: Sunflower and Plant Biology ResearchTitle: Coordinating expression of FLOWERING LOCUS T by DORMANCY ASSOCIATED MADS-BOX-like genes in leafy spurge Author
Submitted to: PLoS One
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/15/2015
Publication Date: 5/11/2015
Citation: Hao, X., Chao, W., Yang, Y., Horvath, D. 2015. Coordinating expression of FLOWERING LOCUS T by DORMANCY ASSOCIATED MADS-BOX-like genes in leafy spurge. PLoS One. 10(5):e0126030. DOI:10.1371/journal.pone.0126030. Interpretive Summary: Two genes that appear to regulate bud dormancy in perennial weeds and crops are the gene FLOWERING LOCUS T (FT for short) and DOMANCY ASSOCIATED MADS-BOX (DAM for short). FT prevents dormancy when it is allowed to accumulate in the fall, and thus there must be mechanisms to turn this gene off in order to allow plants to go dormant so they can survive the winter. DAM has similarities to a gene called SHORT VEGETATIVE PHASE (SVP) in the model annual plant Arabidopsis thaliana. SVP has been shown to bind to and turn off FT to prevent flowering if the annual plant has not experienced a cold winter (a process called vernalization). We hypothesized that DAM might be required for dormancy induction in order to bind to and turn off FT in perennials. Thus, we first examined the accumulation of DAM and FT genes in the invasive perennial weed leafy spurge, and demonstrated that DAM genes are turned on during dormancy-inducing conditions, and FT genes are subsequently turned off. We also used an antibody designed to bind to the DAM gene from leafy spurge and show it was able to bind to a sequence in the promoter (the region of the gene required for turning it on or off) or FT.
Technical Abstract: Leafy spurge is a noxious perennial weed that produces underground adventitious buds, which are crucial for generating new vegetative shoots following periods of freezing temperatures or exposure to various control measures. DORMANCY ASSOCIATED MADS-BOX (DAM) genes have been proposed to play a direct role in the transition to winter-induced dormancy and maintenance through regulation of FLOWERING LOCUS T (FT). To explore the regulation of FT by DAM and its impact of dormancy transitions in leafy spurge (Euphorbia esula L.), two DAM splice variants and two different FT genes were cloned and characterized. Under long-photoperiods (16 h light), DAM genes are expressed in a circadian fashion and have increased expression in leaves, stems, shoot tips, and crown buds. For FT genes, transcription was affected by light and transcripts were detected mainly in leaves and flowers. Under dormancy inducing conditions, DAM and FT genes had an inverse expression pattern. Moreover, underground adventitious buds transitioned from paradormancy to endodormancy when FT genes were repressed. Chromatin immunoprecipitation assays were performed using DAM protein specific antibodies to demonstrate that DAM directly bound to a cryptic CArG box in the promoter regions of FT genes isolated from endodormant crown buds. These results are consistent with the hypothesis that DAM genes play a crucial role in leafy spurge dormancy transition and maintenance through negatively regulating FT genes.