Cloning And Function Of SoHMA3 Gene In Sorghum Dochna Snowden

Cadmium(Cd)is a biologically unnecessary heavy metal element which causes harm to plants and animals.It is urgent to control soil Cd pollution because soil heavy metal pollution accounts for about 1/6 of the total cultivated land.Phytoremediation is considered to be an effective and economically effective method.Hyperaccumulation plants have small biomass and are difficult to survive compared with high biomass plants.Sorghum dochna(Forssk)Snowden,a food crop,that can be used for biofuel production since it has characteristics compared to other sorghum varieties,such as tall stalks,thick stems,and higher biomass production.Heavy metal ATPase(HMA)is a specific transport protein of heavy metal ions in plants.A large number of studies have shown that the high expression of HMA3 in hyperaccumulation plants responds to heavy metal stress,which is one of the main factors for its hyperaccumulation ability.In this study,physiological and biochemical responses of Sorghum under cadmium stress was revealed,a complete sequence of SoHMA3,that was screened from the transcripts of Sorghum at different stress concentration and expressed by gene cloning and expression.Yeast cleavage and RT-PCR were used to analyze the expression and function of yeast in different stress concentration of seedlings.The main finding are as follows:(1)The results of biomass sorghum seedlings stressed with different Cd concentrations showed that:Tolerance to Cd stress in Sorghum with a concentration of less than 30 ?mol/L showed high tolerance.When Cd concentration was higher than 30?mol/L,it would have a significant poisoning effect on Sorghum.Chlorophyll showed a negative correlation with the increase of Cd stress concentration.The continuous increase of malondialdehyde(MDA)and soluble protein content indicates that Sorghum suffered severe membrane lipid peroxidation and membrane damage.The peroxidase(POD),catalase(CAT)and superoxide dismutase(SOD)showed a positive response to low concentration of Cd stress,a negatively response to high concentration of Cd stress.(2)Cloning of the gene of interest and bioinformatics analysis can be obtained:the full-length sequence of SoHMA3 gene was cloned which was 3179 bp,encoding 877 amino acids,with a predicted molecular mass of 94.44 kD and a basic isoelectric point of 6.4.It is a transmembrane protein belonging to the HAD superfamily.Phylogenetic tree analysis showed that the protein was most closely related to Sorghum bicolor and Zea mays.In addition,the heterologous expression of SoHMA3 in yeast affects the tolerance and resistance to cadmium.(3)The qRT-PCR technique was used to analyze the expression changes of SoHMA3 to Cd stress.The result showed that SoHMA3 wass expressed in both at different times and tissues.The SoHMA3 gene had no significant change with the increase of Cd stress concentration in aboveground sample,an increasing trend in underground samples,and the expression level decreased with the extension of the stress time,the highest expression in 30 ?mol/L cadmium stress for 6 h.Based on results,it can be presumed that the protein is mainly expressed in the root,which may be one of the early responsive proteins to cadmium stress,and participates in the detoxification process of sorghum by biomass.