Functional Analysis Of The Transcription Factor FUSCA3 In Brassica Napus

As an important oil crop in China,rapeseed rape has significantly increased the output of rapeseed oil to increase the self-sufficiency of edible oil,which is a major demand for the country.At present,the molecular biological mechanism of lipid formation in plant seeds and its metabolic regulation mechanism have been studied.The transcription factor has become a new research hotspot because of its multiple target genes.However,the mode of action and regulation mechanism of FUSCA3(FUS3)transcription factors regulating lipid synthesis remain unclear.In this study,BnaFUS3 gene was cloned from "Xianyou 15" and its function was analyzed.The main results are as follows:(1)CDS sequences of BnaA2.FUS3 and BnaA6.FUS3,two copies of BnaFUS3 gene was cloned from Brassica nupus ‘xiangyou15’.The CDS of the two copies were 927 bp and 948 bp,with the length of corresponding encoded 309 and 315 amino acids,the amino acid sequence variation occurred in the C-terminal.Hydrophilic proteins BnaA2.FUS3 and BnaA6.FUS3 belong to B3 family,are membrane protein with no transmembrane region.Homology shows that both BnaA2.FUS3 and BnaA6.FUS3 are homologous genes of BraFUS3 and AtFUS3.(2)Fluorescent relative quantitative analysis shows that the BnaA2.FUS3 was expressed in roots,stems,leaves and horns,and was relatively stable in seeds,while the expression of peak value was appeared in pod skin of 25 days after pollination.BnaA6.FUS3 is highly expressed in seeds and peaks at 35 days after pollination.The expression of BnaA2.FUS3 and BnaA6.FUS3 showed a similar M-type trend in pod skin The relationship between the expression of BnaFUS3 and accumulation of fatty acids in seed showed that,the expression BnaA2.FUS3 and BnaA6.FUS3 are rapidly increasing at 30 days after pollination,while this time each fatty acid was entering the rapid growth period.The expression of two copies changed little at 45 days to 50 day after pollination,and the accumulation of fatty acid also entered the slow growth period and became stable.This indicates that BnaFUS3 has an important influence on embryogenesis and development of Brassica napus,and played an important role in fatty acid synthesis and lipid accumulation.(3)Under stress analysis,the expression of BnaFUS3 could be induced and promoted under 6-BA,drought and high temperature(40℃)stress conditions.The induction of BnaA2.FUS3 by 6-BA was greater than that by BnaA2.FUS3,while by the drought,the induction effect of BnaA2.FUS3 was greater than that of BnaA6.FUS3;salt stress,low temperature(4℃)environment,inhibited the expression of BnaFUS3,in which short time salt stress inhibited BnaA6.FUS3 more than BnaA2.FUS3,and low temperature treatment inhibited BnaA2.FUS3 more than BnaA6.FUS3;ABA and water stains have a large fluctuation in the expression of BnaFUS3.(4)Analysis of BnaFUS3 transformed Arabidopsis,BnaFUS3 promoted the accumulation of oleic acid,inhibited the accumulation of palmitic acid,linoleic acid and linolenic acid;while BnaA2.FUS3 promoted the accumulation of oleic acid was greater than BnaA6.FUS3,inhibited the accumulation of linoleic acid also larger than BnaA6.FUS3;both of them have little effect on stearic acid and arachidonic acid.(5)The BnaFUS3 gene was transformed into Brassica napus and a positive regeneration seedling was obtained by tissue culture.