Identification And The Function Of Aegilops Tauschii AetHIPP28 To Cadmium Stress Based On Transcriptome Sequencing

Cadmium（Cd）is one of the most toxic heavy metals and a common soil pollutant.It is easily absorbed by plants and accumulates in different tissues and enter the food chain and subsequently harm human health.Wheat is an important food crop grown worldwide and the second most consumed crop in China.Reducing Cd accumulation in wheat grain is an important issue for human health.Aegilops tauschii（DD,2n=2x=14）is a donor of the D genome of common wheat,which is considered as a good and less exploited source for increasing the genetic potential of cultivated wheat to various biotic and abiotic stresses.In this study,the Aegilops tauschii（accession number KU-2126）was used as the plant material and treated with cadmium chloride（Cd Cl₂·5H₂O）for transcriptomic sequencing,which excavated the key genes in response to cadmium stress,and verified the gene function,laying the foundation for the creation of low cadmium wheat.The following research results were obtained:In the root tissues,a total of 3169 differentially expressed genes were detected at 2 d of cadmium treatment（T2R）and control（CKR）,with 1197 genes significantly up-regulated and down-regulated and 1972genes significantly down-regulated.Whereas there were 1303up-regulated and 1865 down-regulated genes,respectively,when the seedlings were treated with Cd for 5 d.In the shoots tissues,there were1880 up-regulated and 2209 down-regulated gene,respectively,in the seedlings treated with Cd for 2 d.Nevertheless,there were 4644differential genes observed for 5 days（T5S）and control（CKS）,with1674 significantly up-regulated,and 2970 were significantly down-regulated,1379 differential genes,819 and 560 genes significantly down-regulated for cadmium 2 d（T2S）and 5 d（T5S）.Differential genes analysis between different groups indicated that 73 differential genes were detected at the roots and 203 were detected at the shoots.However,there were 167 up-regulated and 183 down-regulated by analyzed the differentially expressed transcription factors.Subsequently,the function of Heavy Metal-associated Isoprenylated Plant Protein 28（Aet HIPP28）was investigated.The length of Aet HIPP28 is 516 bp,encoding 171 amino acids.Subcellular localization analysis revealed Aet HIPP28 localization to the nucleus and the cytoplasmic membrane.It suggests that Aet HIPP28 is present in both organelles.The molecular weight of the Aet HIPP28 protein is18,911.94.The isoelectric point is 7.78 and the total mean hydrophobic index（GRAVY）is-0.578 by analysis of the Aet HIPP28gene.Investigation reveals that the secondary structure of Aet HIPP28protein,α-helix（Alpha helix）is 19.88%,β-folding（Beta turn）2.92%,elongation chain（Extended strand）19.30%and unregular coil（Random coil）57.89%.Beyond that Aet HIPP28 gene expression was significantly up-regulated in both roots and leaves by quantitative real-time fluorescence detection under treatment with 50μM Cd Cl₂·5H₂O solution.Further,the Agrobacterium tumefaciens-mediated method was carried out that the Arabidopsis（Col0）transformation.The results showed that overexpression of Aet HIPP28 significantly improved cadmium tolerance in Arabidopsis,promoting the root growth under cadmium stress,and increasing cadmium accumulation in plants.Physiological and biochemical index was measured that the ROS content of transgenic Arabidopsis was significantly lower than WT under cadmium stress and the viability of antioxidant enzymes was significantly higher than WT,indicating that Aet HIPP28 can regulate the ROS accumulation and antioxidant enzyme vitality of Arabidopsis,and then regulate the cadmium resistance of Arabidopsis.