| Sugar beet (Beta Vulgaris L) is a kind of biennial crop which develops vegetatively in the first year and comes into the reproduction period in the next year.But in some cases,sugar beet can directly comes into the reproduction period in the first year and bolting.As the great part of photosynthetic products are consumed to the reproduction,the production of sugar beet root tuber decrease about 10-20% compared with non-bolting sugar beet,and the sugar content decrease about 0.8 - 1.6%.The technological quality becomes bad and difficulty to be stored.The earlier the sugar beet bolts,the more the production decreases. The later the sugar beet bolts,the more the sugar content decreases. Sugar beet bolting significantly affected the production of root tuber and brings erros in breeding work.So we should analyse the reasons of sugar beet bolting and find some anti-bolting ways.As to the reasons of sugar beet bolting,the researches from domestic and abroad show that genetic and ecological conditions both affect sugar beet bolting which can be asorted to internal and external causes.The former is genetic aspects and the latter is the ecological conditions.The gene controls bolting and the external factors supply the needed conditions for sugar beet bolting. The external factors mainly are vernalization and photoperiodism,i.e. low temperature and day length.Moreover,the nutrition and hormones also affect sugar beet bolting.No matter what conditions, low temperature,day length,nutrition and hormones are external factors,they must function through internal factor i.e bolting-controled gene.Therefore.to study the mechanism of biennial sugar beet bolting in the first year,we must isolate bolting related genes and understand the structure,the expression model etc.,which explain the bolting mechanism on molecular level.Differential expression gene induced with low temperature in bolting sugar beet was studied and the main experimental results were as follows:l.The experiment were carried out in artificial climate incubator.The sugar beet buds were grown under the condition of 16h light and 4℃ for 72 days which induce sugar beet to bolt.The total RNA was isolated from stem apex of sugar beet buds. Reverse transcription of 1st strand and synthesis of double strand of cDNA were carried out.3 pairs of primers were synthesized and differential expression gene fragment was analysed through the cDNA-RDA method.The fragment was cloned and sequenced,which was 323bp in length and named DP3 .DP3 was submitted to GenBank database,and the accession number is AY326073.2. Based on the sequence of DP3 ,gene specific primers were designed and a sequence of 693 bp in length was obtained through the 3'-RACE and 5'RACE methods.3.According to the sequence obtained through the RACE methods, gene specific primers were designed and a PCR amplification was done with Ty7 cDNA as the template.A 609bp fragment was aquaired ,which was cloned and sequenced and named as Ty7Br600. The accession number is AY324115 in GenBank database. Blastn with database of GenBank,there is no homology with the Ty7Br600 fragment,and show no homology in database of Arabidopsis either.So we suggusted that it maybe a new relative gene of bolting sugar beet.4.Two PCR amplifications was carried out with Ty7 DNA and TA33 DNA as the template respectively.Two fragments were aquaired , and then cloned and sequenced and named as Ty7Br900 and TA33Br600 which were 855bp and 609bp respectively.They were submitted to GenBank database,and the accession number is AY32114 and AY32113.Compared with Ty7Br600 by Sequence Alignment program of DNAMAN 4.0,a intron of 235bp in length was found in Ty7Br900,whose left boundary was GT and AG the right.This result shows no difference with the general intron boundary of plant. In the TA33Br600, no intron was found, but there was one base difference at 513bp.We infer that the intron and the one base difference maybe related with the mechanism of sugar beet bolting.5.To sum up the predicted results of DNAMAN 4.0,PHD,SOSUI and...
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