Genome-wide Analysis Of The Barley Lipid Transfer Protein Gene Family

Barley(Hordeum vulgare)is widely grown around the world as a winter cereal.It is used as stock feed and a main supply of malt in brewing industry.Protein is the main nutritive component of barley grains.For malting barley,the level of grain protein is used to estimate the amount of soluble carbohydrate.The higher the protein level,the lower the potential carbohydrate level and the grain is less suitable to produce brewery.Lipid transfer proteins(LTPs)are small proteins,which are involved in lipid transfer,as well as plant disease resistance,cutin and wax synthesis and reproductive development.The categorization of LTPs has been studied in rice(Oryza sativa),Arabidopsis,maize(Zea mays)and sorghum(Sorghum bicolor),based on glycosylphosphatidylinositol(GPI)modification site,sequence similarity,intron position and the spacing pattern of eight cysteines.However there is no report on barley LTP sequence analysis.In this thesis,we identified barley protein sequences and classified 70 barley LTPs using bioinformatic method,based on previous LTP classifications and barley sequencing.We further studied their gene expression in different developmental tissues.The major findings of this dissertation were listed as follows:1.Base on sequence information on The Plant Genomics Resource website,we identified LTP sequences of rice,Arabidopsis and barley.We grouped proteins based on phylogenetic relationships.According to Rice and Arabidopsis study,LTPs in barley are divided into five types(1,2,C,D and G).2.We analyzed protein characteristics including signal peptide,the amount of amino acids,molecular weight,p I value,GPI site,intron number and subcellular localization.After aligning eight cysteine motifs of70 LTPs,we found similar protein characteristics and specific 8CM consensus in same types.3.We analyzed the chromosome distribution of 70 LTPs and onbserved gene clusters of Hv LTPs,implying their possible origin from tandem duplications during the evolution.4.Based on RNA-seq data on IPK website,we performed hierarchical clustering of 69 LTPs in 15 distinct tissues.The expression pattern analysis shows different patterns of these LTPs in different tissues,suggesting their diverse biological functions.In short,we systematically analyzed barley LTPs and grouped them in5 types and uncovered their diverse expression patterns,providing a baisis for future barley LTP functional analysis.