Molecular responses to thermal stress in woody plants

Abstract

Stress caused by high and low temperatures has been much less studied in woody plants than in herbaceous ones. The cold response shows specific traits in woody plants. Cold acclimation associated to winter dormancy develops in two sequential steps: the first is triggered by photoperiod shortening while the second requires temperatures to fall. The involvement of ABA in cold acclimation is beyond question, yet the roles played by this hormone are far better understood in herbaceous plants. The induction of protective proteins and changes in both glycan metabolism and circadian clock functioning are noteworthy among the molecular responses of woody species to low temperatures. Both herbaceous and woody plants seem to respond similarly to heat stress, with heat shock proteins (HSPs) dominating protein synthesis profiles. Certain HSPs are also induced in response to low temperatures, and recent data suggest that they are involved in cold acclimation.Key words: cold acclimation, heat stress, dormancy, HSP, ABA. Resumen Respuestas moleculares de las plantas leñosas al estrés térmicoEl estrés que producen las altas y las bajas temperaturas ha sido menos estudiado en las plantas leñosas que en las herbáceas. La respuesta al frío en las especies leñosas presenta características propias. La aclimatación al frío asociada a la dormancia invernal se desarrolla en dos etapas secuenciales: la primera es inducida por el acortamiento del fotoperiodo, y la segunda requiere una disminución de las temperaturas. Se ha comprobado una implicación del ABA en este proceso, sin embargo su papel es menos claro que el que tiene en la aclimatación de las plantas herbáceas. Entre las respuestas moleculares de los árboles al frío se deben destacar la inducción de proteínas protectoras, los cambios en el metabolismo de los glúcidos y la alteración en el funcionamiento del reloj circadiano. El comportamiento de las plantas leñosas frente al calor no parece tener peculiaridades específicas, siendo la síntesis de las proteínas de choque térmico (HSPs) la respuesta más significativa a nivel molecular. Algunas HSPs también se inducen en respuesta a las bajas temperaturas, y datos recientes sugieren que pueden estar implicadas en la aclimatación al frío.Palabras clave: aclimatación al frío, choque de calor, dormancia, HSP, ABA.

Development of a molecular test to determine the vitality status of Norway spruce (Picea abies) seedlings during frozen storage

“…Although certain groups were more abundant, it does not necessarily indicate the importance of one group over another. Genes corresponding to cell defence included known antifreeze genes, such as dehydrins and pathogenesis-related genes like IV chitinase, b-1-3-glucanase and thaumatin-like genes (reviewed by Gómez et al 2005;Joosen et al 2006). Furthermore genes encoding HSPs were induced in response to cold stress.…”

“…Interestingly, this included also genes of which it is known that they function in hormonal signal transduction pathways, such as the abscisic acid (ABA) transduction pathway. Biochemical and genetic studies in the past have shown that ABA is increased when exposed to a low temperature and triggers processes leading to increased frost tolerance (Marek et al 1992; reviewed by Gómez et al 2005;Joosen et al 2006). Cell wall modification is necessary to protect the cell against freeze-induced stress.…”

“…The transcript level of several genes associated with sugar, amino acid, lignin, and secondary metabolism were positively correlated with the freezing tolerance status. Soluble sugars have been shown to play an important role, in the protection of cellular membranes and act as osmoprotectants and primary messengers in signal transduction pathways (Wanner and Juntilla 1999;Hincha et al 2000;Smeekens 2000; reviewed by Gómez et al 2005;Yuanyuan et al 2009). Lowtemperature stress influences the metabolism of nitrogenous compounds, in particular certain amino acids and polyamine compounds (Mazzucotelli et al 2006;Davey et al 2009).…”

“…Furthermore genes encoding HSPs were induced in response to cold stress. HSPs act as strong cryoprotectors by participating in membrane protection, refolding of denatured proteins, and act against protein aggregation (reviewed by Gómez et al 2005). Higher proportions of differentially regulated genes were found to be involved in metabolism.…”