Cloning, Expression Analysis Of GolS Gene And Studies On Desiccation Tolerance Of Brassica Napus Seeds

Nearly all orthodox seeds terminate their maturation phase with a severe desiccation and desiccation tolerance was acquired during this period.However,the mechanism of the desiccation tolerance acquisition in seeds is still unclear.The rapeseeds(Brassica napus L.DEYOU No.5) were used in this study to investigate the onset of desiccation tolerance.The time course of desiccation tolerance acquisition,obtained by seed desiccation tolerance test,showed that the desiccation tolerance started between 18 and 20 DAF and was achieved at 35 DAF.The soluble carbohydrate components and content were determined during the maturation of rape seeds by high performance liquid chromatography(HPLC).The results showed that,the reducing sugar(e.g.glucose and fructose) content decreased significantly while the non-reducing sugar including sucrose and raffinose family oligosaccharides(RFOs) accumulated except verbascose.The accumulation of RFOs permitted preventing the injury of membrane caused by sucrose crystallizing under desiccation stress,and survived the seeds.The tatio of RFOs to sucrose increased along with the seed development,so it's thought to be an evaluation indicator of desiccation tolerance.Using rapid amplification of cDNA end(RACE) technology,one gene encoding galactinol synthase(BnGolS-1) was successfully cloned from rapeseeds.Sequence analysis showed that the full-length cDNA of BnGolS-1 was 1384 bp in length contained an open reading frame(ORF) of 1029 bp.Then,its transcription level in seeds during maturation was analysed by semi-quantitative RT-PCR.The BnGolS-1 didn't show the detectable transcription until 24 DAF of seed development,a little later than the start of desiccation tolerance acquisition,demonstrating that the expression of BnGolS-1 gene might be induced by desiccation signal and it might need a certain time to response.