Isolation And Function Analysis Of OfFT?OfSOC1 And OfAP1 In Osmanthus Fragrans 'Sijigui'

Osmanthus fragrans is one of the top ten traditional flowers and a common landscaping tree in China,which can be divided into once flower and seasonal flower according to flowering period.Once flower type only blooms in autumn within one year;seasonal flower type grow flowers in multiple seasons,among which the flowers in autumn are large and concentrated with cymbidium and no stalks,while in spring and winter,the flowers are panicles and inflorescences.In this study,gene FT,SOC1 and AP1 in Osmanthus fragrans were cloned by PCR and RACE,the expression of flower genes were analyzed by RT-PCR.The key factors FT and SOC1 were tested for Arabidopsis transformation experiments.The main results were as follows:(1)The c DNA sequences of Of FT,Of SOC1 A,Of SOC1 B and Of AP1 were cloned from'Yanhonggui' and 'Fodingzhu',whose ORFs were 525 bp,657 bp,651 bp and 720 bp,respectively.The DNA sequences of Of FT DNA from 'Yanhonggui' and 'Fodingzhu' both contains 4 exons and3 introns,but the lengths were 2034 bp and 2041 bp,respectively.RACE clone found there are two forms of alternative splicing trancripts of Of FT from 'Yanhonggui' and 'Fodingzhu',which are the third exon is deleted and the fourth exon is deleted separately.(2)Onion epidermal cell subcellular localization result showed Of FT was expressed on the cell membrane,Of AP1 was expressed on the nucleus and cell membrane,Of SOC1 A and Of SOC1 B were expressed on the nucleus.RT-PCR analysis of tissues and organs revealed that Of FT,Of SOC1 and Of AP1 were expressed high level in flower buds,but low level in the vegetative organs.RT-PCR analysis of 'Fodingzhu' flowering in autumn and winter seasons showed that Of FT and its homologous gene Of TFL1 have different expression patterns in autumn and winter,while the expressions pattern of Of SOC1 and Of AP1 genes are basically the same,which may be one of the factors that cause the continuous flower in seasonal flowering type.(3)For the transformation of Of FT,Of SOC1 A and Of SOC1 B into Arabidopsis thaliana,the transgenic lines showed early flowering characteristics compared with wild type,which further indicated that the Of FT,Of SOC1 A and Of SOC1 B genes all have the function of promoting flowering.The results of this study lay a foundation for further exploration of the flower-forming principle of Osmanthus fragrans and the molecular mechanism of the flowering of the seasonal flowering type,and provide guidance for the artificial regulation of Osmanthus fragrans.