title: Photoperiod- and temperature-mediated control of phenology in trees - a molecular perspective.
abstract: Contents 511 I. 511 II. 512 III. 513 IV. 513 V. 517 VI. 517 VII. 521 VIII. 521 Acknowledgements 521 References 521 SUMMARY: Trees growing in boreal and temperate regions synchronize their growth with seasonal climatic changes in adaptive responses that are essential for their survival. These trees cease growth before the winter and establish a dormant state during which growth cessation is maintained by repression of responses to growth-promotive signals. Reactivation of growth in the spring follows the release from dormancy promoted by prolonged exposure to low temperature during the winter. The timing of the key events and regulation of the molecular programs associated with the key stages of the annual growth cycle are controlled by two main environmental cues: photoperiod and temperature. Recently, key components mediating photoperiodic control of growth cessation and bud set have been identified, and striking similarities have been observed in signaling pathways controlling growth cessation in trees and floral transition in Arabidopsis. Although less well understood, the regulation of bud dormancy and bud burst may involve cell-cell communication and chromatin remodeling. Here, we discuss current knowledge of the molecular-level regulation of the annual growth cycle of woody trees in temperate and boreal regions, and identify key questions that need to be addressed in the future.
authors.affiliation: Department of Forest Genetics and Plant Physiology, SLU, S-901 83, Umeå, Sweden.
authors.forename: Rajesh Kumar
authors.initials: RK
authors.lastname: Singh
authors.affiliation: Department of Physical Geography and Ecosystem Science, Lund University, Sölvegatan 12, S-223 62, Lund, Sweden.
authors.forename: Tetiana
authors.initials: T
authors.lastname: Svystun
authors.affiliation: College of Science, King Saud University, 11451, Riyadh, Saudi Arabia.
authors.forename: Badr
authors.initials: B
authors.lastname: AlDahmash
authors.affiliation: Department of Physical Geography and Ecosystem Science, Lund University, Sölvegatan 12, S-223 62, Lund, Sweden.
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Jönsson
authors.affiliation: Department of Forest Genetics and Plant Physiology, SLU, S-901 83, Umeå, Sweden.|College of Science, King Saud University, 11451, Riyadh, Saudi Arabia.
authors.forename: Rishikesh P
authors.initials: RP
authors.lastname: Bhalerao
mesh_terms: D014644:Genetic Variation; D017440:Photoperiod; D057445:Plant Dormancy / Q000502:physiology; D012621:Seasons; D013696:Temperature; D014197:Trees / Q000235:genetics / Q000254:growth & development / Q000502:physiology*
keywords: correlation analysis; evolution; phloem; phylogeny; sieve element; sieve plate; sieve pore; trees