Functional Analysis Of Wood-associated Transcription Factor MYB156 And MYB221 From Populus

MYB transcription factor is one of the largest family of transcription factors in plants and plays an important role in the process of plant growth and in response stress.The study on the regulation of MYB transcription factor on lignin,cellulose and hemicellulose in poplars has important reference value for the understanding of wood formation mechanism.In order to clarify the regulation functions of MYB221 and MYB156 in the formation of wood,We Cultured transgenic poplars overexpressing or suppressing MYB221 gene,and suppressing MYB221 and MYB156 double genes.The effects of MYB221 and MYB156 in different transgenic poplars for wood formation were detected.The results were as follows:1.Through the laser capture microdissection,we observed that the Xylem became more developed and the numbers of cambium cell were more in transgenic poplars suppressing MYB221 gene,and suppressing MYB221 and MYB156 double genes than that of the wild type.While the result was opposite in transgenic poplars over expressing MYB221 gene.2.Determination of wood composition of transgenic and wild-type poplars,indicated that the lignin content were decreased and cellulose content were increased in transgenic poplars overexpressing MYB221 gene than that of the wild type.While lignin content were increased and cellulose content were decreased in transgenic poplars suppressing MYB221 gene or suppressing MYB221 and MYB156 double genes than that of the wild type.These results suggested that MYB221 negatively regulated lignin synthesis and positively regulated cellulose synthesis.3.The localization of MYB 156,MYB221 and CTL2 were detected by gene gun bombardment of onion epidermis.It was found that MYB156 and MYB221 were localized in the nucleus,and CTL2 was localized in Golgi.4.It is proved that CTL2 has interaction with MYB 156 and MYB221.The interaction between CTL2 and MYB156 led to the increase of lignin related genes expression,and the interaction between CTL2 and MYB221 resulted in a decrease in the expression of genes related to the synthesis of cellulose/hemicellulose and pectin.The interaction between CTL2 and MYB156/MYB221 was correlated with wood development.