The effects of temperature, photoperiod, and vernalization on regrowth and flowering competence inEuphorbia esula(Euphorbiaceae) crown buds

Abstract

The herbaceous perennial weed Euphorbia esula L. (Euphorbiaceae) reproduces by vegetative and sexual means, characteristics that are key to its persistence and survival. In this study, we examined environmental effects on regrowth and flowering under controlled conditions to further validate field observations and set the stage for the future identification of molecular mechanisms involved in the regulation of these processes. Shoot cuttings were exposed to different combinations of decreasing temperatures, decreasing photoperiods, and vernalization, in growth chambers. Subsequently, shoots were removed and regrowth and flowering from new shoots were monitored in a warm temperature greenhouse under long-day conditions. Vernalization alone has no effect on regrowth and flowering. Plants required decreasing temperature followed by vernalization for rapid regrowth and flowering. Decreasing photoperiod at a constant temperature with or without vernalization had no significant effect on regrowth and flowering. In conjunction with previous field research, the results suggest that a gradually decreasing temperature is required as one of the components for flowering competence and vernalization is determinate for reproductive development under long-day conditions. Résumé : La plante adventice herbacée pérenne Euphorbia esula L. (Euphorbiaceae) se reproduit par des moyens végétatifs et sexuels, des caractéristiques qui constituent une clé pour sa persistance et sa survie. Les auteurs ont examiné les effets environnementaux sur le bouturage et la floraison sous des conditions contrôlées, pour confirmer les observations de terrain et mettre en place ce qui est requis pour identifier les mécanismes moléculaires impliqués dans la régulation de ces processus. Ils ont exposé des boutures à différentes combinaisons de températures décroissantes, de photopériodes décroissantes et de vernalisation en chambres de culture. Par après, on a prélevé les tiges et on a suivi leur reprise ainsi que la floraison sur les nouvelles tiges, dans une serre à température chaude sous des conditions de jours longs. La vernalisation à elle seule demeure sans effet sur la floraison. Les plantes nécessitent une température descendante suivie d'une vernalisation pour une reprise rapide avec floraison. Une diminution de la photopériode à température constante avec ou sans vernalisation reste sans effet significatif sur la reprise et la floraison. Avec ceux de recherches antécédentes sur le terrain, ces résultats suggèrent qu'une diminution graduelle de la température est une composante requise pour l'aptitude à fleurir et que la vernalisation est déterminante pour le développement reproductif sous des conditions de jours longs.

Role of Temperature in Dormancy Induction and Release in One-year-old Seedlings of Lilium longiflorum Populations

“…Our results were also inconsistent with woody perennials (Anderson et al, 2005;Foley et al, 2009;Heide and Prestrud, 2005;Moss, 1969;Svendsen et al, 2007). In the meristems of Mediterranean temperate grasses, endo-dormancy apparently starts during early winter by pre-exposure to short days and low temperatures (Ofir and Dorenfield, 1992), and develops under increasing daylength and temperature (McWilliam and Kramer, 1968;Ofir et al, 1967;Ofir and Kerem, 1982;Ofir and Kigel, 1999).…”

Meta-Analysis Identifies Potential Molecular Markers for Endodormancy in Crown Buds of Leafy Spurge; a Herbaceous Perennial

“…The transition from endo-to ecodormancy requires an extended period of cold temperatures and usually occurs in late November to early December in the Northern Hemisphere. The discovery that transition from endo-to ecodormancy is also the point at which crown buds become flower competent Foley et al 2009) provided evidence to support the hypothesis that cross-talk occurs 1 Diagram of leafy spurge anatomy and environmental factors associated with transition from para-to endodormancy. Underground adventitious buds (UABs) are located on the underground stem (crown buds) and on the lateral roots (root buds).…”

“…The environmental parameters required for inducing well-defined phases of dormancy in UABs of leafy spurge have previously been determined under field or controlled environmental conditions (Foley et al 2009). As illustrated in Fig.…”

“…To eliminate environmental variability under field conditions, standardized growth chamber conditions for followup transcriptome studies included exposing 3-month-old greenhouse-propagated plants to a ramp down (RD) in photoperiod (16-h → 8-h light) and temperature (27 → 10 °C ) over 12 weeks. This treatment induced a para-to endodormant transition in UABs, whereas an additional 8-12 weeks of vernalizing cold treatment (5-7 °C ) induced a transition from endo-to ecodormancy (Foley et al 2009). However, leafy spurge plants exposed to a RD in temperature alone (RDt; 27 → 10 °C ) under a constant photoperiod of 16 h or a RD in photoperiod alone (RDp; 16-h → 8-h light) at a constant temperature of 26 o C (Foley et al 2009) did not induce endodormancy in UABs.…”

Increase in ACC oxidase levels and activities during paradormancy release of leafy spurge (Euphorbia esula) buds

“…In buds, dormancy is subdivided into three categories: (i) ecodormancy in which growth cessation is controlled by external environmental factors, (ii) paradormancy or correlative inhibition in which growth cessation is controlled by physiological factors external to the affected structure, and (iii) endodormacy or innate dormancy in which growth cessation is controlled by internal physiological factors (Lang et al 1987). We found that in leafy spurge, paradormancy inhibits buds from developing into new shoots through signals generated from the actively growing aerial portion of the plant, namely auxin and sugars (Horvath 1998(Horvath , 1999Chao et al 2006) and endodormancy is triggered by cold temperature and short photoperiods (Foley et al 2009;Doğramacı et al 2013).…”