Functional Study Of BpWOX4 Gene In Betula Platyphylla Suk.

In our country,Betula platyphylla Suk.is a prominent tree species that is extensiv ely distributed.The advantages of Betula platyphylla Suk.include compact wood,moderate hardness,straight grain,and resistance to disease and insect pests.It has excellent environmental and economic benefits.Yet,given the scarcity of wood and the prevalence of saline-alkaline soil in China,it is crucial to increase birch wood’s resistance to salt stress.The transcription factor WOXs is essential for plant development.Betula platyphylla Suk.was used as the experimental item in this investigation.First,the genetic transformation of the BpWOX4 gene into Betula platyphylla was carried out using an agrobacterium-mediated zygote after the creation of RNAi inhibitory expression vectors and overexpression vectors.to learn more about how they function under salt stress and how they contribute to secondary growth and development.The results are as follows.(1)Nine WOX genes were discovered in Betula platyphylla by comparing the genomes of Arabidopsis thaliana and this plant.Real-time fluorescence qu Reversetative analysis and bioinformatic analysis of these nine WOX genes under various tissue conditions and salt stress showed that the BpWOX4 gene was specifically expressed in the root and phloast,indicating the hat BpWOX4 gene may be involthe ved in secondary growth of Betula platyphylla.The upregulated expression of this gene under salt stress indicated that it was induced by salt stress.The Therefore,BpWOX4 gene was selected as the experimental object for further research.(2)The BpWOX4 gene was cloned from Betula platyphylla,and a vector for its overexpression and inhibition was created.The genetic transformation of Birch was carried out using a zygotic embryo mediated by Agrobacterium tumefaciens,and the transgenic strain was produced.After six months of seedling development,the growth of transgenic birch was observed,and statistical analysis revealed no appreciable differences in plant height between inhibited expression transgenic birch,wild-type birch,and overexpressed transgenic birch.However,inhibited expression transgenic birch could not support upright growth due to abnormal xylem development.Overexpressed transgenic strains had considerably larger ground diameter and fresh weight than wild-type birch,whereas inhibited transgenic strains had a significantly smaller ground stem and fresweightsht than wild-type birch.(3)By cross-cutting the stem segment of half-year old birch,the microscopic structure of birch was observed by benchtop scanning electron microscope and chemical staining.The results showed that the secondary xylem development of Birch with BpWOX4 gene overexpression was significantly enhanced,and the xylem became wider.Compared with wildtype Birch,the cambium area of birch with BpWOX4 gene overexpression was wider.At the same time,the number of layers increased significantly.These results suggest that overexpression of BpWOX4 in birch promotes the growth of betula cambium.As the activity of cambium intensifies,xylem differentiation intensifies.The cambium of birch plants inhibited from expressing BpWOX4 gene was obviously damaged,and the lignification of the primary phloem and xylem could be completed.However,the secondary growth the of xylem was affected,while the growth of the secondary phloem did not decrease significantly,resulting in the growth path of xylem the being extremely irregular and the being evelopment was extremely abnormal.This suggests that the BpWOX4 gene may be involved in the development of birch cambium.(4)Under salt stress,overexpressed strains showed obvious growth advantages compared with wild-type and inhibited strains.Physiological indexes and histochemical staining showed that Birch BpWOX4 overexpressed strains had obvious salt tolerance.In conclusion,the BpWOX4 gene of Betula platyphylla is involved in regulating the development of cambium and also improves the salt tolerance of Betula platyphylla,which lays a foundation for further research on the growth and stress resistance mechanism of betula platyphylla.