Study On The Physiological And Molecular Mechanism Of Overexpression Of AmRosea1 Gene Regulating Leaves Redness In 84K Poplar

Anthocyanins as polyphenolic pigments,which are widely found in various tissues of plants,such as flowers,stems,leaves and fruits.84 K poplar(Populus alba × Populus glandulosa)is a hybrid,which is an excellent material for poplar genetic engineering research,due to extensive distribution,fast-growing and highly genetic transformation rate.Am Rosea1 belongs to the R2R3-MYB transcription factor,as a key factor in regulating Antirrhinum(Antirrhinum majus)pigments by the distribution and density.Therefore,we construction of Am Rosea1 overexpression vector in 84 K poplar by genetic transformation,aim to analyze its regulatory pathway of anthocyanin and reveal the network controlling for genetic improvement of colorful leaf in poplar.The experimental results were as follows.In this study,12 transgenic lines were obtained by constructing an overexpression vector of Am Rosea1 gene for heterologous transformation in 84 K poplar,and phenotypic observation revealed that Am Rosea1 activated the biosynthesis of anthocyanin,which resulted in a red phenotype of poplar leaves.The transgenic lines were treated with optical signal and physiological indexes were measured.Under different light intensities,compared with the LED light treatment,the leaves of the transgenic lines became redder,in which the anthocyanin content and soluble sugar content were increased,and the chlorophyll content and POD activity were decreased under natural light.After 30 d of different light treatments,the LED red-blue light treatment that the anthocyanin content raised,the soluble sugar content and POD activity declined,and the chlorophyll content added slightly under LED red and blue light induction compared with LED red and blue light.According the experimental results,it was speculated that both natural light and red-blue light treatment could activate anthocyanin biosynthesis in 84 K poplar,but since the light intensity and flux density of natural light were significantly higher than other light qualities,it indicated that red-blue light was an indispensable light quality for anthocyanin biosynthesis and light intensity was an important factor affecting anthocyanin biosynthesis.To reveal the anthocyanin synthesis pathway of Am Rosea1 in 84 K poplar,transcriptomic analysis was performed and a total of six c DNA libraries were constructed.170 differentially expressed genes were screened,of which 86 genes were up-regulated and 84 genes were downregulated.Sixteen candidate genes related to anthocyanin biosynthesis were screened by GO annotation KEGG enrichment analysis.The metabolome analysis showed that 13 anthocyanins-related differentially accumulated metabolites(DAMs)were detected in AM.It was found that the key metabolite regulating the reddening is cyanindin in 84 K poplar.Meanwhile,the transcriptomic and metabolomic joint analyses showed that 18 DEGs were negatively or positively associated with 13 DAMs,including 11 MYB genes,two BZ1 genes,one FG2 gene,one ANS gene and three IF7 MAT genes.Phylogenetic analysis showed that Am Rosea1 had high homology with Pag MYB113,and MYB113 was directly co-expressed with BZ1,ANS and DFR.It is speculated that Am Rosea1 might substitute MYB113 to activate anthocyanin biosynthesis structural gene in 84 K poplar.