Preliminary Study On Hydrangea NRAT1 Gene Response To Aluminum Stress

Aluminum stress is the main factor limiting the growth of plants in acid soil.Hydrangea is a kind of aluminum rich plant.Previous studies have shown that Hydrangea plants can accumulate a lot of aluminum ions in acid soil without affecting the growth and development.In this study,Hydrangea.macrophylla cv’laybla’was used as the material to clone the full length of NRAT1（NRAMP aluminum transport 1）gene in the NRAMP（natural resistance-associ TED macrophage protrin）gene family and conduct bioinformatics analysis;Then total RNA was extracted for RT-PCR amplification to detect the expression of NRAT1 gene in different tissues and at different times.At the same time,the activity and content of a variety of antioxidant enzymes were detected to explore the correlation between the expression of Hydrangea NRAT1 gene and aluminum resistance under aluminum stress,so as to lay a foundation for the analysis of the function of Hydrangea NRAT1 gene.The main results are as follows:I Through bioinformatics analysis of NRAT1 gene,it was found that the full length of NRAT1 gene was 1881 bp,the encoded protein sequence length was 548aa,and the chemical equation was C₂₇₆₉H₄₃₇₉N₆₈₉O₇₄₃S₂₀.This protein is hydrophobic and does not have signal peptide.It contains 12 transmembrane domains.Its location shows that it is mainly distributed in the plasma membrane and vacuoles.There are 5 phosphorylation sites of NRAT1 coding protein.The amino acid sequence of NRAT1 in Hydrangeas has the highest homology with that of Quercus variabilis.The structure of NRAT1 in different plants is highly conserved.NRAT1 encoded protein secondary structure is the main typeɑspiral and random curl,followed by the extension chain,minimal proportion of beta corner structure;Tertiary structure has highly conserved structural characteristics,but NRAT1 protein may have its own unique functions in different plants.II The expression level of NRAT1 gene in root,stem and leaf of Hydrangea was detected by real-time fluorescence quantitative PCR.The results showed that The NRAT1 gene was expressed in root,stem and leaf of Hydrangea Japonica.Under aluminum stress,with the extension of treatment time,the expression of NRAT1 gene showed a trend of first increasing and then decreasing.At 2 h of aluminum stress,the expression of root,stem and leaf all reached the maximum value,and then gradually decreased.After 12 h,the expression level was lower than that of the control group.The expression of NRAT1 gene was also significantly different in different tissues,and the total average expression was root>leaf>stem.III During the process of aluminum stress,the changes of antioxidant enzyme system in Hydrangea were measured.The results showed that exogenous aluminum stress tr eatment could cause the increase of H₂O₂ content in Hydrangea within 1h,and the i-ncrease of hydrogen peroxide content would induce correlation the enhanced enzyme activity protects against aluminum poisoning,such as Catalase,Glutathione reductase,Plain old data structure,Superoxide dismutase and other antioxidant enzymes.When Hydrangea is subjected to aluminum stress,it works together to regulate the Hydrang ea’s physiological activity and remove a large amount of reactive oxygen radicals in t-he plant.However,after the aluminum treatment time reached 4h,the Malondialdehy de content inside the Hydrangea rose rapidly,indicating that the membrane structure of the Hydrangea cells had been destroyed at this time.To sum up,the expression of the Hydrangea NRAT1 gene is rapidly up-regulated under exogenous aluminum stress,indicating that it has the ability to carry aluminum ions for transport and participate in the process of detoxification of aluminum;at the same time,in the process of aluminum stress,the anti-oxidation of Hydrangea in vivo is initiated Biological system to maintain the balance of Hydrangea’s physiological activities.Therefore,the expression of Hydrangea NRAT1 gene is related to the response to exogenous aluminum stress.