Submitted to: Plant Cell and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 13, 2005
Publication Date: December 1, 2005
Citation: Anderson, J.V., Gesch, R.W., Jia, Y., Chao, W.S., Horvath, D.P. 2005. Seasonal shifts in dormancy status, carbohydrate metabolism, and related gene expression in crown buds of leafy spurge. Plant, Cell and Environment. 28(12):1567-1578. Interpretive Summary: Dormancy in crown and root buds of leafy spurge is the main weedy characteristic that allows leafy spurge to escape current control measures. Since environmental and physiological signals are known to influence the dormancy status of plants, we established how environmental factors such as light and temperature and physiological factors such as sugars and hormones correlate with related gene expression and dormancy status in crown buds of leafy spurge. Our data indicates that reduced light and temperature may influence the conversion of starch to sucrose in crown buds during the transition from summer to fall. This period is marked by a transition in dormancy (para- to endo-dormancy). Endo-dormancy appears to play an important role in preventing new shoot growth from crown buds during the period when above ground tissue inhibits growth (para-dormany) to when cold temperatures inhibit growth (eco-dormancy). Cold temperatures were also important for breaking endo-dormancy and causing the crown buds to become flowering competent. Several genes important for production of proteins involved in sugar metabolism were differentially regulated in conjunction with well-defined phases of dormancy in crown buds. Marker genes for other important biological processes were also differentially regulated during transition from para-, endo-, and eco-dormancy. Data from this study was used to develop a model showing potential pathways involved in regulating seasonal dormancy status in leafy spurge crown buds.
Technical Abstract: Crown buds of field-grown leafy spurge (Euphorbia esula, L.) were examined to determine relationships between carbohydrate metabolism and gene expression throughout para-, endo-, and eco-dormancy during the transition from summer, fall, and winter, respectively. Our data indicates that endo-dormancy plays a role in preventing new shoot growth during the transition from fall to winter. Cold temperature was involved in breaking endo-dormancy, inducing flowering competence, and inhibiting shoot growth. An inverse relationship developed between starch and soluble sugar (mainly sucrose) content in buds during the shift from para- to endo-dormancy, which continued through eco-dormancy. Unlike starch content, soluble sugars were lowest in crown buds during para-dormancy but increased over 2 to 3-fold during the transition to endo-dormancy. Several genes (AGPase, HK, SPS, SuSy, and UGPase) coding for proteins involved in sugar metabolism were differentially regulated in conjunction with well-defined phases of dormancy in crown buds. Marker genes for auxin perception, S-phase progression, and cell wall biochemistry were also differentially regulated during transition from para-, endo-, and eco-dormancy. Results were used to develop a model showing potential signaling pathways involved in regulating seasonal dormancy status in leafy spurge crown buds.