Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: November 26, 2008
Publication Date: December 10, 2008
Citation: Horvath, D.P., Chao, W.S., Anderson, J.V. 2009. Cloning, Characterization, Regulation, and Function of DORMANCY-ASSOCIATED MADS-BOX Genes from Leafy Spurge [Abstract]. Plant and Animal Genome Conference. P720. Technical Abstract: DORMANCY-ASSOCIATED MADS-BOX (DAM) genes are transcription factors that have been linked to endodormancy induction. The evergrowing mutation in peach, which renders it incapable of entering endodormancy, resulted from a deletion in a series of DAM genes (Bielenberg et al. 2008). Likewise, DAM genes were shown to be differentially regulated in several plant systems in response to stimuli known to impact endodormancy induction. DAM genes are very similar to SHORT VEGETATIVE PHASE (SVP), a negative regulator of flowering in Arabidopsis thaliana. We have cloned several cDNA and genomic clones of DAM genes from the model perennial rangeland weed leafy spurge (Euphorbia esula). Comparisons of the cDNAs reveal the possibility of a multi-gene family and differential splicing of DAM genes in leafy spurge. Analysis of the promoter of one DAM gene revealed several potential transcription factor binding sites including a CCGAC sequence that regulates cold responsive genes in plants. Cold is the primary environmental signal responsible for inducing endodormancy in leafy spurge. Cold does not play a significant role in poplar endodormancy induction and the promoters of poplar DAM genes lack the CCGAC sequences. However, several other potential transcription factor binding sites are conserved between leafy spurge and poplar, including the circadian-regulating EVENING element. We developed gene specific probes for three different DAM genes from leafy spurge and used them to show that two of the DAM genes were expressed only in meristem tissues and were induced by cold treatments. DAM genes were also preferentially expressed following specific treatments that induced endodormancy in leafy spurge. Böhlenius et al. 2006, showed that over-expression of FLOWERING LOCUS T (FT) in poplar inhibited growth cessation prior to endodormancy induction. Lee et al. 2007, demonstrated that SVP regulates flowering by inhibiting expression of FT in Arabidopsis. DAM expression in leafy spurge is inversely correlated with FT expression. Over-expression of DAM in Arabidopsis resulted in plants that flowered slightly later than wild type. We hypothesize that DAM genes are induced by cold temperatures in leafy spurge and act to induce dormancy by negatively-regulating FT (or similar genes) which then regulate growth cessation and endodormancy induction.