Molecular control of winter dormancy establishment in trees: a review

Abstract

Dormancy is an adaptive mechanism that enables woody plants to survive the freezing temperatures of winter. This complex process is characterized by the cessation of meristem activity, which is accompanied by winter bud set, extensive metabolic remodelling, an acquired high tolerance to cold and, in deciduous trees, by leaf senescence and abscission. The induction of dormancy occurs in response to seasonal environmental signals. In most woody plants, shortening of the photoperiod induces growth cessation, bud set, and some degree of cold acclimation. The subsequent drop in temperature then leads to a greater tolerance to cold and leaf fall. Experimental evidence indicates that the phytochrome system plays an important role as a day length sensor, and it has been recently reported that in poplar (Populus tremula x tremuloides), the photoperiodic control of dormancy induction is driven by a molecular mechanism that shares components with the mechanism of the photoperiodic control of flowering time in Arabidopsis. In contrast, the effects of low temperatures are less well understood. Nonetheless, it has been established that the chestnut (Castanea sativa Mill.) circadian molecular clock is disrupted both during winter and in response to cold, with presumable consequences on the general physiology of the plant. However, there is no direct evidence so far for its role in dormancy regulation.Additional key words: bud set, circadian clock, cold acclimation, endodormancy, photoperiodism, phytochrome. ResumenRevisión. Control molecular del establecimiento de la dormancia invernal en los árboles La dormancia es un mecanismo adaptativo que capacita a las plantas leñosas para sobrevivir a las bajas temperaturas invernales. Este complejo proceso se caracteriza por el cese de la actividad de los meristemos, y va acompañado del desarrollo de las yemas de otoño, de notables modificaciones metabólicas, de la adquisición de una elevada tolerancia al frío y, en las especies caducifolias, de la senescencia y abscisión de las hojas. La inducción de la dormancia responde a señales medioambientales. En la mayoría de las plantas leñosas el acortamiento del fotoperiodo induce el cese del crecimiento, la formación de las yemas de otoño y una moderada aclimatación al frío. Después, la bajada de las temperaturas induce una mayor tolerancia al frío y la caída de las hojas. La evidencia experimental indica que el sistema de los fitocromos juega un papel importante como sensor de la duración del día y recientemente se ha comprobado que el control fotoperiódico de la inducción de la dormancia en chopo ocurre mediante un mecanismo molecular que tiene elementos comunes con el que controla la transición floral en respuesta al fotoperiodo en Arabidopsis. La influencia de las bajas temperaturas es menos conocida. El reloj circadiano del castaño (Castanea sativa Mill.) se altera durante el invierno y en respuesta al frío, lo que debe tener importantes consecuencias sobre la fisiología general de la planta. Sin embargo, no hay todavía evidenc...

Molecular aspects of dormancy in peach (Prunus persica [L.] Batsch.)

“…A first connection between day-length shortening and dormancy induction was observed by Garner and Allard (1923), and later confirmed by others (Kramer et al, 1936; Downs & Bothwick, 1956; Nithsch, 1957; Weieser, 1970;Allona et al, 2008). In photoperiod-insensitive varieties and Euphorbia esula low temperatures replaces the effect of SD (Heide & Pestrud, 2005; Horvath 2009), as it was also described in strawberry (Ito & Saito, 1962;Guttridge, 1985).…”

“…A relationship between ABA and water content under SD or dormancy induced by water stress was (Erez et al, 1998;Fennel & Line, 2001;Rinne et al, 1994;Welling et al, 1997;Koussa et al, 1998), suggesting a link between ABA content and water status with bud dormancy depth (Tamura et al, 1993). After dormancy establishment, a reduction of free water and an accumulation of dehydrins were observed, improving plant tolerance to freezing.A first connection between day-length shortening and dormancy induction was observed by Garner and Allard (1923), and later confirmed by others (Kramer et al, 1936; Downs & Bothwick, 1956; Nithsch, 1957; Weieser, 1970;Allona et al, 2008). In photoperiod-insensitive varieties and Euphorbia esula low temperatures replaces the effect of SD (Heide & Pestrud, 2005; Horvath 2009), as it was also described in strawberry (Ito & Saito, 1962;Guttridge, 1985).…”

“…For the purpose of this work, the term dormancy has been employed to refer to the endodormant state. The physiological and genetic control of bud dormancy has been reviewed by different authors (Arora et al, 2003;Horvath et al, 2003;Allona et al, 2008). In summary, these reviews emphasize the relevant role of day-length shortening, temperature, abscisic acid (ABA), ethylene and gibberellins (GA) as signals affecting bud set and dormancy onset, and discuss some molecular mechanisms related to the process, including cell cycle regulation, modification of the cell water status, and epigenetic regulation.…”

“…Several reviews highlight the role of external (day-length shorteningand temperature) and endogenous factors (growth regulators, cell cycle regulation, water status and chromatin modification) as regulators of bud dormancy onset and release (Arora et al, 2003;Horvath et al, 2003;Baurle & Dean, 2006;Allona et al, 2008).…”

Evaluation of dormancy break in some selected peach (Prunus persica) cultivars

“…This means that dormancy is one of the most important adaptation mechanisms that enable the survival of perennial plants in winter periods of low temperatures (Taylor 2008;Leida 2012). The process of dormancy thus determines how the woody fruit species can survive during the winter season and early spring without any damage to shoots and, above all, flower buds (Allona et al 2008). The final number of flowers that remain after budding or (better to say) the density of their setting is an important factor that influences the fruit-bearing of peach trees.…”