Primary Study On Function Of Oil-Related Genes GmAAPT And GmOLE6 In Soybean

The triacylglycerol(TAG)is the main form of plant oil,which can be used as carbon source and energy storage material.There are two main TAG synthesis pathways in eukaryotesa,one of the ways is Kennedy(glycerophosphate),another way is single acyl glycerin.In the Kennedy way,Phosphatidylcholine(PC)and phosphatidylethanolamine(PE)can be used as acyl donor,with diacylglycerol(DAG)as receptors to synthesis TAG.Aminoalcoholphosphotransferases(AAPT)is the enzyme to generate PC.AAPT genes in plant had been found in arabidopsis,soybean,wheat and rape.There were two AAPT gene families in soybean,named GmAAPT1 and GmAAPT2,the role of GmAAPT1 in regulating seed oil content of arabidopsis had been studied in our laboratory.This paper mainly studied the function of GmAAPT2.Such lipids which were generally stored as TAG in spherical compartments referred to as oilbodies,to supply the energy requirements for the growth of the seedling after germination.Oleosins were the major proteins associated with oilbodies,the TAG was inside of the oil body,the outer layer was the phospholipid bilayer,oleosins were embedded in the phospholipid bilayer,oleosins could stabilize oil body structure.GmOLE6 gene is an oleosin gene,its function was also studied in this paper.The results of studies on two genes were as follows.we expressed the GmAAPT1 and GmAAPT2 protein in prokaryotic cells,biochemical analysis showed that both of them could react with CDP-choline and CDP-ethanolamine to form PC and PE.So they both have the activity of cholinephosphotransferase(CPT)and cholinephosphotransferase(EPT),is a bifunctional enzyme.We used the method of the agrobacterium infection to get the overexpression GmAAPT2 and GmOLE6 transgenic Arabidopsis,and used gas chromatography(GC)to analysis the content of the TAG and fatty acid in Arabidopsis seeds.Results showed that the fatty acid content of GmAAPT2 overexpression plant seeds,C20:0(peanut acid),C22:1(sinapic acid)and C18:3(alpha-linolenic acid)content were obviously increased compared with wild type,but C18:1(oleic acid)content was obviously lower than wild type,showed that GmAAPT2 could catalytic the synthesis of PC and change the content of some unsaturated fatty acid,its function is the same as GmAAPT1.While there had no obvious impacts on the TAG content,seed grain weight and total protein content of GmAAPT2 overexpression seeds.The fatty acid content of GmOLE6 overexpression plant seeds,C20:1(Arachidic Acid)obviously decreased compared with wild type,and the TAG content was alsoobviously reduced,but the seed grain weight and total protein content were elevated alsoobviously compared with wild type.We also studied the effect of GmAAPTs-OE on seed germination.Showed that,with-30℃ cold tolerance,GmAAPT1 and GmAAPT2 overexpression Arabidopsis seed germination rate was lower than wild type.This result indicated that GmAAPT1 and GmAAPT2 might negatively regulate antifreeze during seed germination.These results Will help us to understand the function of genes related seed oil content,fatty acid components and plant resistance.