Genomic studies help refine a model for regulation of endodormancy induction in underground adventitious buds of leafy spurge

Dormancy in underground adventitious buds (UABs) of leafy spurge allows this invasive perennial weed to escape conventional control measures. Previous genomic studies indicated that endodormancy induction in UABs of leafy spurge requires a ramp down in both temperature and photoperiod. To identify potential targets for manipulating dormancy in UABs of leafy spurge, we investigated the individual effects that photoperiod and temperature have on molecular networks associated with endodormancy induction. Gene-set enrichment analyses identified metabolic pathways associated with endodormancy induction, such as ethylene biosynthesis from methionine, flavonoid and IAA biosynthesis, methionine salvage pathway, SAM cycle, gluconeogenesis, glycolysis, and TCA cycle. Further, sub-network enrichment analyses identified putative central hubs involved in circadian rhythm, and stress and hormone responses. These results helped refine our current working model for regulation of endodormancy induction, which highlights a role for AP2/ERF transcription factors as central regulators. AP2/ERF transcription factors include a large family of 147 genes in Arabidopsis that are often associated with induction by abiotic stress.  A recent study by others, showing that a novel peach CBF transcription factor (an AP2/ERF family member) led to short-day induced dormancy in apple, further supports our proposed model. To elucidate how temperature and photoperiod affect AP2/ERF transcription factors in leafy spurge during endodormancy induction, we have characterized expression patterns for 27 of the 31 family members identified in the leafy spurge EST-database. Potential roles of these transcription factors in endodormancy induction and maintenance will be presented.