Identification,phylogenetic And Expression Analysis Of Sugar Transporter Gene In Maize

Maize(Zea mays L.)is one of the most important food crops and feed crops in the world,and is currently the highest-yielding crop nowdays.The energy needed for corn growth and development comes from the carbohydrates produced by photosynthesis.Carbohydrates are transported in the form of sugars(including sucrose,monosaccharides,and sugar alcohols)to heterotrophic tissues such as corn roots,seeds,and flowers for the growth and development of these tissues.They can also act as signaling molecules and osmotic regulators in response to abiotic stress.Sugar transporter is one kind of functional proteins for sugar molecular transportation in maize.At present,there are few studies on the function of corn sugar transporter genes,so exploring the evolutionary rule and gene functions of the maize sugar transporter gene family has theoretical guiding significance for molecular improvement of maize quality and accumulation of biomass.the increase of biomass accumulation.In this study,the homologous BLASTP analysis was carried out in maize genome database by using the domains of various sugar transporter family genes in dicotyledonous Arabidopsis thaliana,and the sugar transporters of the whole maize genome were retrieved;The sequence characteristics,phylogenetic analysis,expression pattern and functional characteristics of each gene family were analyzed in order to provide theoretical basis and genetic resources for maize molecular breeding.The main results are as follows:1.Through the BLASTP homologous alignment analysis,97 sugar transporter genes were identified in the whole genome of maize,which belonged to MFS and MtN3_slv super families like other species.According to the sequence characteristics and gene clustering within the species,it can be divided into 10 subfamilies,including SUT(Sucrose transporter),STP(Sugar transport proteins),SFP(Early response to dehydration-like),PMT(polyol/ monosaccharide transporter),INT(inositol transporter),pGlcT(plastidic glucose transporter),TMT(tonoplastic monosaccharide transporters),VGT(vacuolar glucose transporters)and SWEET(Sugars Will Eventually be Exported Transporters).2.Transmembrane domain predictions indicated that 8 families belonging to the MFS superfamily had 8-12 TMDs typical of MFS.The SWEET protein belonged to the typical MtN3_slv family,and all of the 24 members had 6-7 TMDs except ZmSWEET3 b.3.By analyzing the sequence characteristics and gene structures of each gene family,he gene family of corn sugar transporter was evolutionarily conserved.Members of each gene family have the same conserved motifs,and there were a large number of fully conserved amino acid residue sites,and the identical or similar exon distribution structures.It was found that the insertion or deletion of introns is an important reason for the change of gene length.4.By constructing a phylogenetic tree of plants covering mosses,ferns,oil-free mites,monocots and dicotyledons,it has been found that maize has expanded in the PMT family,which originated from monocots but in corn and other monocots.The rate of amplification increases dramatically after separation.The gene loss occurred in the SFP family,and this loss occurred after the dichotomous plant divergence.In maize,there is the first gene in the same branch as Selaginella,and ZmSTP14 is the earliest evolutionary gene in the maize STP family.ZmSUT2 is the earliest and most conserved SUT gene in maize,it is distributed in the same branch as Amborella trichopoda and dicotyledons,and there also exist the SUT gene of bryophytes and ferns.Among other gene families,ZmINT1,ZmpGlT3/4,ZmPMT1,ZmSFP4,ZmSTP14,ZmTMT4 and ZmVGT1 are the earliest genes in their families respectively.and they have the same ancestors as Amborella trichopoda and dicotyledons.5.Chromosomal localization revealed that the 97 sugar transporter genes in maize were unevenly distributed on all chromosomes,and the sixth chromosome was only distributed with three genes,and the other had more than five gene distributions;the distribution of genes on chromosomes was also unbalanced,mainly concentrated at two ends.It was analyzed that there were 13 genes involved in gene tandem replication to form five tandem replication regions;28 genes were involved in chromosome fragment replication,forming five fragment replication regions.6.The analysis of gene expression patterns by expression profile and semi-quantitative assay showed that most homologous genes had similar expression pattern and that the function of the maize sugar transporter gene is related to the tissue it expresses.The maize sugar transporter gene may have similar functions to its orthologous genes in rice and Arabidopsis.This is also demonstrated by yeast complementation experiments with candidate genes.