|其他摘要||Brassinosteroids (BR) are essential hormone for plant growth and development, and also protect plants from a variety of environment strsses, such as cell elongation and division, pollen fertility, photomorphogenesis, adjusting the structure of cell wall and enhancing resistance. Current research focused on annual herbs, such as Arabidopsis thaliana, rice, Solanum lycopersicum and so on, For widely distributed woody plants in nature is less known, the study on Populus (P. euphratica) BR signaling pathway transcription factor PeBZR1 / PeBES1 is a preliminary inquiry to elucidated the role of PeBZR1 / PeBES1 gene in Populus BR signal transduction and improving capabilities of plant defense, providing a theoretical basis knowledge of BR signal in other woody plants, and making us have more accurate understanding the difference between woody and herbaceous inbiosynthesis and metabolic mechanisms of the BR signal. It also provides a theoretical basis for the using of PeBZR1 / PeBES1 gene in modified trees and crops.
The results are as follows:
(1) P. euphratica and P. russkii BZR1 / BES1 gene expression have larger difference under drought, salt and copper stress. The expression of P. euphratica BZR1 / BES1 gene relatively stable and P. russkii has gradually increased under salt stress. Through analysis gene expression of differential tissue, BZR1/BES1 gene is active in stems, leaves and roots of the two Populus. BZR1 gene expression has little difference in different tissues of P. euphratica, the BZR1 gene expression of P.russkiiis roots least, leaves medium, stems up. BES1 gene expression of P. euphraticaia is smaller changer, BES1 gene expression of leaves of P. russkiiis significantly higher than other organizations.
(2) By bioinformatic prediction the physical and chemical properties of PeBZR1 / PeBES1 protein, and observed the subcellular localization of two transcription factors expression in Neuclear through tobacco protoplasts. Moreover, constructed phylogenetic tree of PeBZR1 / PeBES1 gene and analysis functional element of the promoter, and obtained two gain of the functions vector PeBZR1-1D and PeBES1-1Dfrom PeBZR1 / PeBES1 by overlapping PCR.
(3) The over-expression vector 35S::PeBZR1 and 35S::PeBES1 was transformed into tobacco leaves, analysisthe outcome of physiological and biochemical indexes under different concentrations of salt. Under different salt concentrations, the over-expression of transgenic tobacco lines have significantly increased in SOD, POD and CAT enzyme activity compared with the control, and the degree are differences in transgenic lines; osmotic adjustment including proline and soluble sugar content also showed a significant increase, PeBZR1 transgenic lines were significantly higher than PeBES1, MDA content decreased, hydrogen peroxide content decreased and soluble protein content increased of the PeBZR1 / PeBES1 transgenic lines compared with the control, and the expression of NtNHX1 and NtHAK1 genes have significantly different level between transgenic lines and the control in different concentrations of salt stress. it may indicat that PeBZR1 / PeBES1 transcription factors indirect regulating the expression of these two salt tolerance gene.The result revealstransforpmeBZR1 / PeBES1 gene line of tobacco has significantly higher than the control in the salt tolerance and promote the normal growth of tobacco under salt stress.Transgenic seeds germination experiments also proved genetically improved seed germination rate, root length and α-amylase under different stress conditions.|