QTL Relatived To Early Maturing And Cloning Of A Flower Timing Gene BnGI In Brassica Napus.l

Brassica napus L. is a kind of oilseed rape with the biggest plantingarea in our country with advantage of possessing strong resistance andhigh yield. And it is an important crop with high production andeconomic value because its widely usage in our daily life anddevelopment of industry. Early-maturing oilseed rape has a betteradaptability for production model in the main producing areas of ourcountry, which can take full advantage of natural conditions to increaseyield and economical value. So early-maturing has been a hot topic ofrapeseed breeding. Location and analysis of relative traits by usinggenetic maps is an important method of marker-assisted selectionbreeding. Flowering time is a precocious trait for determining maturing.Research on regulation genes of floweing time in Brassica napus L. hasalso been an important development direction of breeding.Two morphologically and molecularly distinguished advancedbreeding lines, late-maturing inbred‘Ronghua’and eraly-maturing inbred‘09-24074’ provided by Shanghai academy of agricultural science,were selected as mapping parents in this study. An F2populationincluding286individuals was obtained by hybridization. A total of582pairs of SSR markers were used to construct linkage map and therefore tolocate QTL related to early maturing. The result showed that only97(16.67%) markers showed polymorphism between two parents andonly57markers showed polymorphism among F2population. A total of32SSR markers were mapped into12linkage groups. The map spanned552.3cM. The range of distance between loci was from0.7cM to45.3cM. And the average distance is17.3cM. Five QTLs for traits related to earlymaturing were detected.A cDNA fragment of GIGANTEA gene was cloned by using materialsof Brassica napus.L DH lines which were obtained by microspore culturecoming from F1hybridization between early-maturing inbred ‘10-544’and ‘10-4336’ selected by Shanghai academy of agricultural scienceaccording to the method of homologous cloning with the sequence ofArabidopsis thaliana GI as seeding sequence. The outcome indicated thatthere are3516bp long of this gene cDNA coding region, which canencode1171amino acids. It has99%homologies with sequence ofBrassica rapa GI and87%homologies with sequence of Arabidopsisthaliana GI. The mature protein isoelectric point is at pH8.47andmolecular weight is127.15kDa. In addition, the BnGI protein predictedpredominant location is the nucleus. Analyzed results of semi-quantitativefluorescence PCR showed that BnGI is expressed in different tissues ofthe oilseed rape uesd in our research, such as roots, stems, apicalmeristem, leaves, flowers and so on. On the other hand, the expressionmode of BnGI characterized with tissue-sepcific expression level.