Location: Sunflower and Plant Biology ResearchTitle: Dehydration and vernalization treatments identify overlapping molecular networks impacting endodormancy maintenance in leafy spurge crown buds) Author
Submitted to: Functional and Integrative Genomics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/3/2011
Publication Date: 12/1/2011
Citation: Dogramaci, M., Horvath, D.P., Christoffers, M.J., Anderson, J.V. 2011. Dehydration and vernalization treatments identify overlapping molecular networks impacting endodormancy maintenance in leafy spurge crown buds. Functional and Integrative Genomics. 11(4):611-626. Interpretive Summary: Leafy spurge is a perennial weed that regenerates new shoots from an abundance of underground buds located on its root system. Well-defined phases of dormancy allows these buds to persist over time, making control by conventional methods difficult.To increase our knowledge aimed at biologically-based management, we examined the effects of dehydration on bud endodormancy and flowering. Only three days of dehydration-stress was required to break bud endodormancy; however, the dehydration treatment did not induce flowering. Interestingly, previous studies have shown that prolonged-cold treatment both breaks endodormancy and induces a vernalization response leading to flowering. Thus, in this study, we compared global gene expression data obtained from buds exposed to short-term dehydration and prolonged-cold as an approach to identify overlapping molecular mechanisms unique to endodormancy maintenance and flowering. Our analyses indicated that endodormancy maintenance involves specific growth regulators, transcription factors, pathways associated with hormone-signaling, chromatin modification, circadian rhythm, and carbohydrate metabolism. Overall, these results suggest that endodormancy maintenance in underground buds of leafy spurge involves multiple networking pathways, requiring cross-talk among growth regulators.
Technical Abstract: Leafy spurge (Euphorbia esula L.) is an herbaceous perennial weed that reproduces vegetatively from an abundance of underground adventitious buds (UABs), which undergo well-defined phases of seasonal dormancy (para-, endo- and eco-dormancy). In this study, the effects of dehydration-stress on vegetative growth and flowering potential from endodormant UABs of leafy spurge was monitored. Further, microarray analysis was used to identify critical defense- and signaling-pathways of transcriptome profiles associated with endodormancy maintenance in UABs. Surprisingly, only 3-day of dehydration-stress is required to break the endodormant phase in UABs; however, the dehydration-stress treatment did not induce flowering. Interestingly, previous studies have shown that prolonged-cold treatment of UABs breaks endodormancy and induces a vernalization response leading to flowering. Thus, in this study, comparing transcriptome data from UABs exposed to short-term dehydration and vernalization provided a unique approach to identify overlapping molecular mechanisms involved in endodormancy maintenance and floral competence. Analysis of transcriptome data associated with breaking endodormancy by both environmental treatments identified LEC1, PHOTOSYSTEM I RC, and brassinosteroids as common central hubs of up-regulated genes, while DREB1A, CBF2, GPA1, MYC2, bHLH, BZIP, and flavonoids were identified as common central hubs of down-regulated genes. The majority of over-represented gene sets common to breaking endodormancy by dehydration-stress and vernalization were down-regulated, and included pathways involved in hormone-signaling, chromatin modification, and circadian rhythm. Additionally, these over-represented gene sets highlighted pathways involved in starch and sugar degradation, and biogenesis of carbon skeletons, suggesting a high metabolic activity is necessary during the endodormant phase. Overall, our results suggest that endodormancy maintenance in UABs of leafy spurge involves multiple networking pathways, requiring cross-talk among growth regulators.