title: Molecular control of seasonal flowering in rice, arabidopsis and temperate cereals.
abstract: BACKGROUND
  Rice (Oryza sativa) and Arabidopsis thaliana have been widely used as model systems to understand how plants control flowering time in response to photoperiod and cold exposure. Extensive research has resulted in the isolation of several regulatory genes involved in flowering and for them to be organized into a molecular network responsive to environmental cues. When plants are exposed to favourable conditions, the network activates expression of florigenic proteins that are transported to the shoot apical meristem where they drive developmental reprogramming of a population of meristematic cells. Several regulatory factors are evolutionarily conserved between rice and arabidopsis. However, other pathways have evolved independently and confer specific characteristics to flowering responses.
  
  
  METHODS
  This review summarizes recent knowledge on the molecular mechanisms regulating daylength perception and flowering time control in arabidopsis and rice. Similarities and differences are discussed between the regulatory networks of the two species and they are compared with the regulatory networks of temperate cereals, which are evolutionarily more similar to rice but have evolved in regions where exposure to low temperatures is crucial to confer competence to flower. Finally, the role of flowering time genes in expansion of rice cultivation to Northern latitudes is discussed.
  
  
  CONCLUSIONS
  Understanding the mechanisms involved in photoperiodic flowering and comparing the regulatory networks of dicots and monocots has revealed how plants respond to environmental cues and adapt to seasonal changes. The molecular architecture of such regulation shows striking similarities across diverse species. However, integration of specific pathways on a basal scheme is essential for adaptation to different environments. Artificial manipulation of flowering time by means of natural genetic resources is essential for expanding the cultivation of cereals across different environments.
authors.affiliation: University of Milan, Department of Biosciences, Via Celoria 26, 20133 Milan, Italy.
authors.forename: Roshi
authors.initials: R
authors.lastname: Shrestha
authors.affiliation: University of Milan, Department of Biosciences, Via Celoria 26, 20133 Milan, Italy.
authors.forename: Jorge
authors.initials: J
authors.lastname: Gómez-Ariza
authors.affiliation: University of Milan, Department of Biosciences, Via Celoria 26, 20133 Milan, Italy.
authors.forename: Vittoria
authors.initials: V
authors.lastname: Brambilla
authors.affiliation: University of Milan, Department of Biosciences, Via Celoria 26, 20133 Milan, Italy fabio.fornara@unimi.it.
authors.forename: Fabio
authors.initials: F
authors.lastname: Fornara
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects; D003080:Cold Temperature; D002523:Edible Grain / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects; D035264:Flowers / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant; D018519:Meristem / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D012275:Oryza / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects; D017440:Photoperiod; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D012621:Seasons; D013312:Stress, Physiological / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D014157:Transcription Factors
keywords: Arabidopsis thaliana; Oryza sativa; cereals; florigen; flower development; photoperiodic flowering; rice; vernalization