Submitted to: Plant Dormancy Symposium
Publication Type: Abstract Only
Publication Acceptance Date: April 15, 2009
Publication Date: June 3, 2009
Citation: Horvath, D.P., Sung, S., Kim, D. 2009. Cloning, Characterization, Regulation, and Function of Dormancy-Associated MADS-Box Genes from Leafy Spurge. 4th International Symposium on Plant Dormancy Program and Abstract Book. Page 18.
DORMANCY-ASSOCIATED MADS-BOX (DAM) genes are SHORT VEGETATIVE PHASE–Like MADS box transcription factors linked to endodormancy induction. We have cloned and characterized several cDNA and genomic clones of DAM genes from the model perennial weed leafy spurge (Euphorbia esula). We present evidence for a multi-gene family and/or differential splicing of DAM genes in leafy spurge. Phylogenetic footprinting on DAM genes of poplar and leafy spurge identified potential regulatory elements including CBF and EVENING element binding sites suggesting cold and circadian regulation of these genes. Chromatin immunoprecipitation experiments revealed histones in specific regions of both leafy spurge DAM promoters are modified during the transition between endodormancy and ecodormancy. We developed gene specific probes for several leafy spurge DAM genes and used them to show that two of the DAM genes were expressed preferentially in meristem tissues and were induced by cold treatments and to a lesser extent by short day lengths. Circadian regulation is being investigated and results from these ongoing experiments will be presented. DAM gene expression was correlated to endodormancy induction in leafy spurge, and over-expression of DAM1 in Arabidopsis resulted in delayed flowering and slower bolt growth. Our published hypothesis is that DAM genes are regulated primarily by temperature in leafy spurge and act to induce dormancy by negatively-regulating FT (or similar genes) which then regulate growth cessation and endodormancy induction. Ongoing chromatin immunoprecipitation experiments to look for binding of DAM proteins to regulatory sequences in FT and TFL homologues of leafy spurge and will be discussed.
Key words: DAM genes, leafy spurge, underground adventitious bud, flowering, dormancy, chromatin remodeling.