| Populus,as a model species of forest research,plays an important role in basic research.At the same time,its trunk is straight,its growth adaptability is strong,its growth is rapid,its forest time is short,its timber yield is high,and its rotation cutting cycle is shorter than that of other species,so it can be used in various manufacturing industries.It is the main economic tree species,and it is planted in a large area around the world as a fast-growing tree.NAC transcription factor,as a special transcription factor,plays a major role in plants,such as regulation in the process of vegetation growth and development,and stress response in the face of biotic and abiotic stresses,and it has become a potential candidate gene to enhance plant stress resistance.In this study,PtNAC101 gene was obtained by RT-PCR,and the transgenic poplar with PtNAC101 gene obtained by Agrobacterium-mediated petiole and internode stem segment method was treated with salt.The phenotype of seedlings and physiological indexes related to antioxidant enzymes were studied,and the response of PtNAC101 gene to salt stress and its role in plants were found out.The main research results are as follows:(1)The PtNCA101 gene of Populus tomentosa was cloned by homologous cloning method.The full length of the gene was 1080 bp,which encoded 360 amino acids,and its accession number was Potri.001G404400 The N-terminal region has a highly conserved NAM domain,so it belongs to NAC gene family.Semi-quantitative PCR results showed that PtNCA101 gene was highly expressed in roots,phloem,xylem and male flowers of Populus tomentosa,but weakly expressed in leaves and not expressed in female flowers.PtNAC101 does not respond to the induction of drought stress,but highly responds to the induction of salt stress.Genes play a certain role in the stress response of salt stress.PtNAC101 was induced to express five hormones NAA(1-Naphthylacetic acid),GA3(Gibberellin A3),ABA(Abscisic Acid),BR(Brassinolide)and Ethrel(ethylene).PtNAC101 may be involved in the transduction process of plant signal hormones.(2)The plant overexpression vector PtNCA101-pPZP211 was established.The constructed overexpression vector plasmid was transferred into GV3101 Agrobacterium tumefaciens,and the wild poplar was infected by petiole method.Two positive poplar plants were selected for follow-up experiments.(3)After salt stress treatment of transgenic seedlings with PtNCA101 gene,the overall growth state of transgenic seedlings under salt stress was not as good as that of wild type.Analysis on the whole plant level showed that PtNCA101 reduced the salt tolerance of transgenic poplar and increased the salt sensitivity.(4)After salt treatment,the physiological indexes showed that the MDA content of OE(Overexpression)poplar was significantly higher than that of the WT poplar(Wild type),and the activities of SOD(Superoxide dismutase),POD(Peroxidase)and CAT(Catalase)of OE-3 and OE-5 poplar were greatly inhibited.OE poplar reduced the antioxidant capacity of plants by inhibiting the activities of antioxidant enzymes,and PtNCA101 played a negative regulatory role under salt stress.. |
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