title: PtFLC homolog from trifoliate orange (Poncirus trifoliata) is regulated by alternative splicing and experiences seasonal fluctuation in expression level.
abstract: In many plant species, exposure to a prolonged period of low temperature during the winter promotes flowering in the spring, a process termed vernalization. In Arabidopsis, the vernalization requirement of winter annual ecotypes is caused by a MADS-box gene FLOWERING LOCUS C (FLC), which is a repressor of flowering gene. Here, a MADS-box gene was isolated from an early flowering trifoliate orange mutant (precocious trifoliate orange, Poncirus trifoliata L. Raf) by the RACE method combined with a cDNA library. Phylogenetic analysis reveals that the MADS-box gene is more closely related to the homologs of the FLOWERING LOCUS C lineage than to any of the other MIKC-type MADS-box lineages known from Arabidopsis. The expression profile of the MADS-box gene by real-time PCR showed upregulation of PtFLC during the winter, followed by a decrease in the spring and summer. This kind of cycling is contrary to the pattern observed in Arabidopsis. In situ hybridization reveals that the MADS-box gene is predominately expressed in the vegetative and reproductive meristems. In addition, five alternatively spliced transcripts of the MADS-box gene were also isolated at juvenile and adult mutant developmental stages. Expression analysis of these transcripts at different developmental stages indicated involvement of alternative splicing during phase change. The information suggests a complicated regulation mechanism in seasonal response and flower formation in perennial woody plants.
authors.affiliation: Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Science, Huazhong Agricultural University, 430070, Wuhan, China. jinzhizhang@webmail.hzau.edu.cn
authors.forename: Jin-Zhi
authors.initials: JZ
authors.lastname: Zhang
authors.forename: Zhi-Min
authors.initials: ZM
authors.lastname: Li
authors.forename: Li
authors.initials: L
authors.lastname: Mei
authors.forename: Jia-Ling
authors.initials: JL
authors.lastname: Yao
authors.forename: Chun-Gen
authors.initials: CG
authors.lastname: Hu
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D017403:In Situ Hybridization; D026161:MADS Domain Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics*; D032104:Poncirus / Q000235:genetics*; D020033:Protein Isoforms / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012621:Seasons; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
chemical_list: D018076:DNA, Complementary; D026161:MADS Domain Proteins; D010940:Plant Proteins; D020033:Protein Isoforms