Cloning And Functional Analysis Of Very Long-chain Fatty Alcohol Synthetase Gene BdFAR 2 In Brachypodium Distachyum

Drought disaster occurs frequently in China,causing dramatic losses every year.As an important crop in China,wheat production suffers from natural disasters including drought,plant diseases and insects,which has impacted its yield and grain quality.Therefore,one important objective of breeding is to improve the drought resistance of crops.In recent years,with the indepth study on waxy components of crops and their biological functions,more and more attentions have been brought into this area.It has been shown that in Arabidopsis and wheat that the fatty acyl-coenzyme a reductase（FAR）is involved in the biogenesis of fatty alcohols from fatty acids.Thus,in this project,a very long-chain fatty alcohol synthetase coding gene BdFAR 2 in Brachypodium distachyum was cloned and transformed into yeast and wild Brachypodium distachyum,respectively.Conseqent functional analyses were further carried out.The results are summarized as the follows:1.The analysis of the wax in Brachypodium distachyum shows that components of the epicuticular wax are primary alcohol,fatty acid,aldehyde and alkane.The primary alcohol is the highest content,particularly the C₂₆6 alcohol.Fatty acid,aldehyde and alkane are relatively lower in content than primary alcohol.The epicuticular wax crystal is in platelet form on both the adaxial and abaxial sides of leaf.2.A bioinformatics analysis was carried out to compare the protein sequences between the target coding gene in Brachypodium distachyum and the wax synthesis-related gene in wheat.A very long-chain fatty alcohol synthetase gene was thereby successfully cloned from Brachypodium distachyum,and was named BdFAR 2.3.Result on heterologous expression of BdFAR 2 in yeast shows that the function of BdFAR 2 is to synthesize the C₂₄4 and C₂₆6 alcohols in wax.4.Result on the over-expression of BdFAR 2 in Brachypodium distachyum shows that BdFAR 2 significantly increases the content of primary alcohol,particularlly the main component C₂₆6 alcohol.These results indicate that BdFAR 2 is an alcohol-producing FAR,through the involvement in the synthesis of waxy fatty alcohol,primarily the C₂₆6 alcohol.Taken together,through the investigation of the very long-chain fatty alcohol synthetase gene BdFAR 2 of monocotyledonous Brachypodium distachyum,this study is expected to provide necessary referencse for futher study of wheat wax biology.