Identification And Characterization Of The DUF642 Family In Maize

DUF642 is a highly conserved plant cell-associated protein of unknown function and belongs to a seed plant-specific protein.It has not been found so far in algae,mosses and most ferns.Its function may be related to a novel symbiotic trait mechanism in seeds.The DUF642family of proteins interacts with the pectin structure of the cell wall and participates in the modification of the physicochemical properties of plant cell walls,responding to plant development or environmental signals.This type of protein not only plays a role in the growth and development of plants,but also responds to plant stress,for example,plays an important role in drought,salt damage,aluminum toxicity.To further explore stress-related genes in maize,the whole members of DUF642 family were identified using bioinformatics methods.Their evolutionary relationships,gene structure,protein structure,chromosome location and cis-elements in the promoter region were systematically studied.Besides,the expression patterns of the DUF642 family in two maize inbred lines B73 and 178 were performed under drought,salt damage and aluminum stress.The main research results are as follows:1.Bioinformatics analysis of maize DUF642 family genesA total of 11 DUF642 gene family members were identified in the maize genome.Phylogenetic tree analysis,gene structure,protein structure and conserved motif data of multiple species indicated that the members of the maize DUF642 family were highly conserved and consistent in evolution.ZmDUF64208 is closely related to the aluminum stress gene Os04g0494900,and it is speculated that it is also an aluminum stress-related gene.The protein tertiary structure showed that the DUF642 protein had a high structural repeatability with?-galactosidase,acetylgalactosidase and xylanase C,indicating that the maize DUF642family proteins are a kind of conserved cell wall proteins.The promoter cis-element analysis showed that the drought-inducing element was shared by 11 maize DUF642 genes,and it was speculated that the maize DUF642 gene is likely to be associated with drought stress.Transcriptome expression data showed that the maize DUF642 family genes had different expression patterns at different developmental stages and in different tissues.The expression level of maize DUF642 genes in the roots was higher than that in the leaves.In addition,ZmDUF64201,ZmDUF64207,ZmDUF64210 and ZmDUF64211 have higher expression levels than other family members in the embryos during seed development,indicating that they also play an important role in seed development.2.Analysis of stress induced expression patterns of maize DUF642The maize seedlings were firstly cultured in liquid solution with oxygen and then the two-leaf seedlings were subjected to stress treatment of 40?M/L AlCl3,200 mM/L NaCl and20%PEG6000.The treatment time points were 6 h,12 h,24 h and 48 h.The results showed that in the B73 inbred line,ZmDUF64201,ZmDUF64202,ZmDUF64203,ZmDUF64204,ZmDUF64205,ZmDUF64206,ZmDUF64208 and ZmDUF64209 genes were down-regulated in the leaves under AlCl₃,NaCl and PEG treatment while ZmDUF64207,ZmDUF64210 and ZmDUF642011 were up-regulated.However,the expression level decreased after 24 h treatment;in the root,the expression levels of the whole ZmDUF642 family were up-regulated.In 178 inbred lines,all genes were down-regulated under AlCl3 and Kept a low level,NaCl and PEG treatment in the leaf while up-regulated in the root.The ZmDUF64207,ZmDUF64210 and ZmDUF642011 genes were highly expressed in roots in both inbred lines.The expression of ZmDUF64208 under AlCl3 treatment was higher than that of other treatments.DUF642 gene of 178 inbred lines had higher expression levels in roots than B73inbred lines under each treatment.