title: Nitrogen as a key regulator of flowering in Fagus crenata: understanding the physiological mechanism of masting by gene expression analysis.
abstract: The role of resource availability in determining the incidence of masting has been widely studied, but how floral transition and initiation are regulated by the resource level is unclear. We tested the hypothesis that floral transition is stimulated by high resource availabiltiy in Fagus crenata based on a new technique, the expression analyses of flowering genes. We isolated F. crenata orthologues of FLOWERING LOCUS T, LEAFY and APETALA1, and confirmed their functions using transgenic Arabidopsis thaliana. We monitored the gene expression levels for 5 years and detected a cycle of on and off years, which was correlated with fluctuations of the shoot-nitrogen concentration. Nitrogen fertilisation resulted in the significantly higher expression of flowering genes than the control, where all of the fertilised trees flowered, whereas the control did not. Our findings identified nitrogen as a key regulator of mast flowering, thereby providing new empirical evidence to support the resource budget model.
authors.affiliation: Graduate School of Environmental Sciences, Hokkaido University, Sapporo, 060-0810, Japan; Graduate School of Environmental and Life Science, Okayama University, Okayama, 700-8530, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Miyazaki
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Maruyama
authors.forename: Yukako
authors.initials: Y
authors.lastname: Chiba
authors.forename: Masaki J
authors.initials: MJ
authors.lastname: Kobayashi
authors.forename: Benesh
authors.initials: B
authors.lastname: Joseph
authors.forename: Kentaro K
authors.initials: KK
authors.lastname: Shimizu
authors.forename: Keiichi
authors.initials: K
authors.lastname: Mochida
authors.forename: Tsutom
authors.initials: T
authors.lastname: Hiura
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Kon
authors.forename: Akiko
authors.initials: A
authors.lastname: Satake
mesh_terms: D017360:Arabidopsis / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics; D002241:Carbohydrates / Q000032:analysis; D029964:Fagus / Q000235:genetics* / Q000502:physiology; D035264:Flowers / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D007564:Japan; D026161:MADS Domain Proteins / Q000235:genetics; D009584:Nitrogen / Q000502:physiology*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000502:physiology; D012621:Seasons; D014157:Transcription Factors / Q000235:genetics
chemical_list: C091535:AP1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D002241:Carbohydrates; C418905:FT protein, Arabidopsis; C074747:LFY protein, Arabidopsis; D026161:MADS Domain Proteins; D014157:Transcription Factors; D009584:Nitrogen
keywords: AP1; FT; LFY; floral initiation; floral transition; flowering; gene expression; gene network; intermittent reproduction; life cycle; resource budget model