Identification And Evolution Analysis Of LBD Gene Family In Thinopyrum Elongatum

Thinopyrum elongatum,as one of the important wild relatives of wheat,has excellent resistance and disease resistance traits,and plays an important role in wheat genetic improvement.The LBD gene family is a plant-specific class of transcription factor gene family that are extensively involved in plant growth and development.In this study,we used the genomic data of Thinopyrum elongatum to mine the members of the LBD gene family of Thinopyrum eongatum by bioinformatics methods,which laid the foundation for further research on the excellent genes in Thinopyrum elongatum.We also investigated the evolutionary relationships in wheat and its relatives by collinearity comparison based on the LBD gene family of Thinopyrum elongatum,which provided a reference for studying the evolutionary relationship of wheat and its relatives.The main results of this study are as follows:1.Bioinformatics analysis of whole genome data of Thinopyrum elongatum identified 32 members of the LBD gene family and named them according to their position on chromosomes.The physicochemical properties of the LBD gene proteins showed that the length and molecular weight of the proteins varied widely,the instability index(Ⅱ)showed that most of the proteins were unstable proteins,the grand average of hydropathicity showed that most of the proteins were hydrophilic proteins.According to the protein isoelectric point acidic proteins and alkaline proteins were distributed.In protein secondary structure prediction,alpha-helix and nonregular coil distribution were more.There were certain differences in the tertiary structures of the various LBD gene proteins,but in general the structures were similar.LBD gene protein was distributed in mitochondria,chloroplast,cytoplasm,nucleus and endoplasmic reticulum in subcellular localization.2.The rootless phylogenetic tree of the LBD gene family in Thinopyrum elongatum,Triticum aestivum L.,Oryza sativa L.and Arabidopsis was constructed,and all LBD genes were classified into Class I and Class II two subfamilies and seven categories according to their structural domain characteristics.In each category,there were LBD genes in Thinopyrum elongatum,Triticum aestivum L.,Oryza sativa L.and Arabidopsis.The characteristic structural domains of seven LBD genes were identified by multiple sequence comparison.The characteristic structural domains of each group were basically the same,but there were differences between different classifications and two subfamilies.Gene structure prediction showed that the LBD genes structure of Thinopyrum elongatum were relatively simple containing few or almost no introns,and 10 protein structural domains were predicted.3.The 2000bp region of the upstream sequences of 32 LBD genes were intercepted and analyzed for cis-acting elements.The upstream sequences of the genes were found to be distributed with 12 major categories and 43 minor subcategories of different cis-acting elements,such as light response,multiple hormones,stress response,indicating that the expression of LBD genes were induced by light,hormones,stress and other factors.4.Chromosomal localization results showed that 32 LBD genes were distributed on 7 chromosomes of Thinopyrum elongatum,and there were tandem duplications of the Tel-3E-LBD4 gene and Tel-3E-LBD7 gene on chromosome 3E,Tel-4E-LBD1 gene and Tel-4E-LBD4 gene on chromosome 4E,and 5 pairs of collinearity genes were found in 32 LBD genes.The evolution rates ka/ks for both homologous gene pairs and tandem repeat genes were both greater than zero,which were positive selection in evolution.Among them,three LBD genes,Tel-2E-LBD1,Tel-3E-LBD2 and Tel-4E-LBD3 had collinearity with 9 species.Tel-2E-LBD2,Tel-3E-LBD4,Tel-4E-LBD1 and Tel-4E-LBD6 were the unique LBD genes of Thinopyrum elongatum,while the other 28 LBD genes were highly conserved in evolution.The presence of interchromosomal segmental duplications on chromosomes of partial homologous groups 1 and 3 in the genomes of Triticum aestivum L.,Triticum turgidum L.,Triticum urartu,and Hordeum vulgare.What’s more,there were translocations in part 4 and 5 of the homologous group of chromosomes in the A genomes of Triticum aestivum L.,Triticum L.and Triticum urartu.Intrachromosomal fragment duplication was found on chromosome 4A in Triticum urartu while intrachromosomal translocations and inversions were found on the A genome of common wheat and cone wheat in part 4 homologous groups.