Functional Characterization Of Poplar Wood-Associated Transcription Factor PtoMYB221 Of Populus Tomentosa And Establishment Of Transformation System Of Poplar For Elimination Of Marker Genes

As one of the plant's largest transcription factors family,MYB transcription factor plays an important role in the transcriptional regulation process of secondary cell wall synthesis.Function analysis of MYB transcription factor regulating the lignin biosynthesis in secondary cell wall is advantageous to improve wood quality in poplars.With the application of transgenic technology in forest tree genetics and breeding,it is significant to establish a safe and efficient selection marker gene deletion technology for improving the biological safety of transgenic breeding.The full-length cDNA sequence of Populus tomentosa PtoMYB221 transcription factors were cloned from Populus tomentosa in this experiment.PtoMYB221 was expressed at high levels in the differentiation between xylem and mature xylem through laser capture microdissection combined with microarray and quantitative PCR to detect gene transcriptional expression levels.PtoMYB221 was highly similar to AtMYB4 of negatively regulating the lignin biosynthesis in secondary cell wall..Subcellular localization of PtoMYB221 showed that PtoMYB221 was located in the nucleus.Luciferase assay systems analysis results showed that PtoMYB221 was a negative transcription factors.The transgenic strains transformed by p RNAi-PtoMYB221 had a higher lignifications level by contrast wild type.And there appeared ectopic deposition of lignin at pith.It is initially speculated that PtoMYB221 had a negatively transcriptional regulation for lignin biosynthesis in secondary cell wall;(2)This experiment built a site-specific recombination system with loxPFRT fusion recognition sites and Hspl8.2 promoter and used transient gene expression system of Arabidopsis mesophyll protoplasts to test it.And finally applied it to genetic transformation in poplars.