Study On The Effects Of Poplar Transcription Factors MYB156 And MYB221 On The Characteristics Of Guard Cell Wall And Stomatal Function

MYB transcription factors,one of the common transcription factors in plants,play an important role in the regulation of plant secondary metabolism,signal transduction and stress tolerance.A large number of studies have shown that MYB156 and MYB221 transcription factors play an important role in the regulation of lignin and cellulose.However,we found that MYB156 and MYB221 were specifically expressed in the guard cells of Populus davidiana×P.alba va.pyramidalis.MYB221 single gene inhibits Populus davidiana×P.alba lines.MYB156 and MYB221 genes inhibited the growth of Populus davidiana×P.alba.MYB221 overexpression lines were used to carry out experiments related to the study on the function of guard cells.The specific results are as follows:(1)Through GUS staining of the ProMYB156:GUS in Arabidopsis thaliana,it was found that MYB156 was specifically expressed in the stomatal guard cells of Arabidopsis thaliana and responded to high temperature and ABA induction.Through GUS staining of the ProMYB156:GUS on the leaf of Populus davidiana×P.alba va.pyramidalis,it was found that MYB156 was expressed in the guard cells of Populus davidiana×alba var.pyramidalis,xylem pulp ray and lateral root origin.(2)Drought phenotype:MYB156 single gene inhibited strain;MYB221 single gene inhibited strain;The MYB156 and MYB221 double gene inhibited strains showed obvious drought-sensitive phenotype at 7 days of drought treatment compared with the wild type Populus davidiana×P.alba var.pyramidalis.MYB221 gene overexpression lines with normal growth.Water content of isolated leaves:MYB156 single gene suppressor strain;MYB221 single gene suppressor strain;The water loss rate of MYB156 and MYB221 was faster than that of the wild type Populus davidiana×P.alba va.pyramidalis..The water loss rate of MYB221 gene overexpressed material was little different from that of wild-type Populus davidiana×P.alba var.pyramidalis.Stomatal opening measurement results:Stomatal opening measurement data showed that stomata of transgenic new poplar were not sensitive to ABA,and the ability to close guard cells was impaired.Stomatal density observation under a microscope showed that there was no difference in stomatal density of transgenic strains,and there was no difference in the development and morphological structure of guard cells.The results showed that the occurrence of drought-sensitive phenotype was independent of stomatal density and stomatal development.(3)Search for downstream target genes of MYB156 and MYB221 transcription factors by transcriptome sequencing:By analyzing the transgenic Populus davidiana×P.alba varpyramidalis data of wild-type Populus davidiana×P.alba var.pyramidalis and D22,it was found that there were differentially expressed genes of xyloglucan endotransgluco hydrolase(XTH)gene and Pectin methylestrases(PME)gene in the leaf tissues.The results of real-time fluorescence quantitative PCR analysis showed that there were indeed differences in Pectin methylestrases(PME)genes between transgenic and wild-type Populus davidiana×P.alba varpyramidalis...