Screening And Functional Characterization Of Candidate Genes Involved In Primary Alcohol Biosynthesis Of Cuticular Wax In Wheat(Triticum Aestivum L.)

Cuticular wax is the hydrocarbon consisting of very long chain(VLC)fatty acids including primary alcohol,aldehydes,fatty acid,alkane,ketone and esters.Cuticular waxes are extracellular hydrophobic layer which protect aerial plant organs,and help plant species for adaptation in different environments.Wax deposition and chemical composition vary considerably between in Arabidopsis thaliana and crops.Cuticular waxes play a significant role against major abiotic stresses in plants such as drought,temperature,water stress,high salinity and cold,etc.So,it draws close attention to the scientists to the molecular processes of cuticular wax biosynthesis and its regulation through abiotic stresses factors in crops.In these study found the following result:1.Cuticular wax composition and content of common wheat variety Xiong 979 during grain filling stage were determined.It was found that the waxy components in the flag leaves,leaf sheaths and spikes contained alkanes,fatty alcohols,aldehydes,fatty acids,diketones and hydroxy-?-diketones.Among them,primary alcohols were the main component of flag leaves waxes(58.51%).Diketone is the main component of leaf sheath wax(47.82%),and Alkane is the main component of spikes wax(44.76%).The dominated carbon chain length of alkanes were C29 and C31,the dominated carbon chain length of diketones wax mainly C31,the dominated carbon chain length of primary alcohol was C28 in leaves,and C30 in spike.These results were compared with cuticular wax composition and contents of wheat variety of Bob white.It was found similar trend in the flag leaves,leaf sheaths and spikes with primary alcohol,alkanes,aldehydydes,fatty acid,diketones and hydroxy-?-diketones.But,in spike,most noticible changed in compositions of diketones and hydroxy-?-diketones were found,which were 51% and 36%,respectively.2.In this study,41 Ta FAR family genes were identified in wheat.Thus,32 Ta FAR genes might be involved in the primary alcohols synthesis of wheat wax according to the phylogenetic relationship.Because,these 32 Ta FAR genes were exhibited highly identitical with previously identified 8 Ta FAR genes.All 32 Ta FAR genes have the typical domain of fatty acyl-coenzyme A reductase.3.It was analyzed plant cis-acting regulatory elements of the promoter binding site of Ta FARs genes to understand the potential function.Interestingly,all 41 Ta FAR genes had a MBS site,which was MYB binding site,was involved in drought-inducibility.The result showed that all Ta FAR family genes were indeed involved in drought resistance through the regulation of the MYB transcription factor.Moreover,almost all of the Ta FAR family genes were contained in the hormone response sites of ABA,Me JA or SA.The result revealed that Ta FAR family genes might be response in stress condition though binding hormone responsive cites of ABA,Me JA or SA.The wide distribution of the TC-RICH REPEATS site in the promoter region was found in Ta FAR family genes,suggested that Ta FAR genes could be involved in response to abiotic stresses.4.Functional expression of 7 Ta FAR genes were investigated by transcriptome involved in seedling leaf wax.Among them,two Ta FAR genes e.g.,Ta FAR7-A and Ta FAR7-D were induced primary alcohol in yeast(Saccharomyces cerevisiae).But,Ta FAR7-A and Ta FAR7-D were reported previously as Ta FAR1 and Ta FAR5,respectively,which were induced to produce C22:O-OH.Other five Ta FAR genes did not produce primary alcohol in yeast.Therefore,transgenic plants of them are needed to confirm its reductive activity and wax primary alcohol synthase function in wheat leaf.