Screening Of Wheat Varieties With Low Accumulation Of Cd And Its Molecular Regulation Mechanism

The field experiment was used to analyze the differences in the accumulation of cadmium in the grains of 60 different wheat varieties under the environment of cadmium contaminated soil,and to select wheat varieties with low cadmium accumulation potential.Cluster analysis was carried out using the amount of cadmium accumulation in grains,and 60 wheat varieties were classified into low-cadmium accumulation type,medium-cadmium accumulation type,and high-cadmium accumulation type.The results of double sieving showed that the lowest cadmium accumulation of Y3 had a minimum cadmium content of 0.326 mg·kg^-1,which was 62.8%lower than other wheat varieties.The highest cadmium content of cadmium accumulation variety Y174 is 1.393 mg·kg^-1,which is 73.3%higher than other varieties.TF_grain/shootis significantly less than TF_shoot/rootis the reason for the less cadmium content in the low cadmium accumulation varieties.The hydroponic experiment was used to explore the differences of cadmium accumulation in the candidate wheat varieties at seedling stage.The results showed that the TF_{aboveground/root}of the low cadmium accumulation variety Y3 was significantly lower than that of the high cadmium accumulation variety Y174.The aboveground cadmium variety Y174’s aerial parts and root biomass were significantly negatively correlated with plant cadmium content,while the aboveground part biomass of Y3 variety had no significant correlation with cadmium content.Through the Cd subcellular content distribution test,the ratio of the cell wall components of the Y3 variety Cd from the root to the aerial part is lower than that of Y174 and the soluble component is lower than that of Y174.The adsorption of Cd on the cell wall of Y3 variety is more significant,and Y174 can store a higher proportion of Cd in the soluble part,which is the biochemical mechanism that increases the Cd content in the aerial part of Y174.Through the determination of Cd chemical binding morphology,the acetic acid binding state in the stem of Y3 increased significantly compared to the root.As a Cd low-accumulative variety,Y3 has a biochemical mechanism that adsorbs more heavy metal cadmium to the cell wall.The shoot and root of Y3 and Y174 varieties were subjected to mi RNA transcriptome sequencing.A total of 171 differentially expressed mi RNAs were obtained,23 of which were known mi RNAs and 148 were novel mi RNAs（novel mi RNAs）.Among them,differentially expressed mi R6201 and mi R9664-3p are highly expressed specifically in the low-accumulation Cd wheat variety Y3,which may be involved in the regulation of target genes related to Cd response through primitive cells and hormone regulation and carbohydrate metabolism.