| Ginkgo Biloba L, with a common name of white fruit, is considered as a living fossil. It is used as food, medicine, wood and ornamental tree. It is a dioecious plant. The female tree is different from the male in many aspects , such as karyotype analysis, pattern of peroxidase isozymes and shape of flower. Some experts think Ginkgo has a sexchromosome. Seeds of Ginkgo is used as a dryfood and is full of nutrition. Its juvenile period is too long and seedling will flower after more than ten years. Long juvenile period severely restricts the progress of its breeding and reduces its economic value. To shorten Ginkgo juvenile period , numerous studies on its culture and conventional breeding technology has been done, but success is very little. Ginkgo will come to bearing slightly early by drawfing the tree and its intensive culture. The best way is to breed earlier flowering varieties through biotechnology.Recently, studies on the floral mechanism in Arabidopsis have made great progress. About 80 genes that control or related to plant flowering were identified. LEAFY(LFY), one of floral meristem identity genes, which confers transition from vegetative to floral meristem identity in Arabidopsis, and affects its flowering time. Overexpression LFY gene promotes plant earlier flowering. Successful experiments have been demonstrated in Arobidopsis , aspen, rice and citrus.Although Ginkgo is an old gymnosperm, its LEAFY ortholog will perhaps controls flowering time. Many studies show that LEAFY is high homolog even among distantly related plant species. Exception of these, little studies on tissue culture and transformation of Ginkgo have been done.This paper emphasizes on the isolation , cloning and analysing two Ginkgo orthologs of LEAFY from the male tree. The results obtained were summarized as bellow:1. The genomic DNA of Ginkgo extracted by CTAB method is light brown in color. It is neither digested with restriction endonucleases nor acted as template for polymerase chain reaction (PCR). The method was modified by adding suitable insoluble PVP and higher concentration of p-mercapto ethanol in the extract solution. Using the modified method, high quality genomic DNA prepared from ginkgo, grape and myrica are colorless and are susceptible to digestion with the restrictionendonucleases and can be used as template for PCR.2. GinLFYand GinNdly gene were obtained from the leaf genomic DNA of the male tree of Ginkgo cultivar Dafushou in the mid-April through PCR.The total length of 3450bp of five segments DNA were amplified by PCR. The phylogenic relation and similarity of the gene is full length of LFY-like gene, which is 99% similar both in nucleic acid sequence and amino acid sequences with that of GinLFY f rom the female. Compared with the GinLFY of female, the gene from the male tree is deficient in 3 bp, and mutantion sites exists on the varied region of LFY-like. The intron of the gene have similar characteristics with the LFY like of many plant species. The gene contain two introns and three exons. The full length of GinNdly from the male tree is 1493bp, which is 3 bp lower than the gene from the female tree. Here too the gene has two introns and three exons.LFY and LFY-like proteins from angiosperm contain a proline-rich region near the amino terminal and an acidic central region which is typical for transcriptional activators and may be important for the function of LFYlike protein. The two domain exists in the variable regions of all LFY-like proteins. Unlike angiosperm LFY-like proteins, GinLFY and GinNdly of male tree does not contain the two domain. The similarity of amino sequences between the GinLFYand GinNdly is 60. 2%, which is 9. 8% lower than LFY and FLO (70%). GinLFY(male) amino sequence similarity with LFY, PRFLL (pinus), NEEDLY (pinus) is 50.0%, 80.3% and 58.2%, respectively. GinNdly (male) amino sequence similarity with LFY, PRFLL (pinus), NEEDLY (pinus) is 45. 3%, 58. 2% and 75. 6% respectively.3. Two sense plant expression vectors and two antisense vectors were cons...
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