The Growth,physiological Characteristics And The Leaf Color Related Gene Expression Research Of B.Pendula ’Purple Rain’

Breeders have focused much attention on colorful-leaf plants because of their importance to landscaping.To evaluate the changes of leat color on phenotype,physiology and transcriptome,were measured between Be tula pendula and Be tula pendula ’Purple Rain’.These results shed light on variations of leaf color in birch and help identify important genes for the genetic engineering of birch trees.There were significant variations in leaf color between Betula pendula and Betula pendula’Purple Rain’.The content of chlorophyll,carotenoid and anthocyanin of Betula pendula’Purple Rain’ were increased 42.14%,71.73%and 317.43%respectively compared to those of Betula pendula.There were significant variations in metabolite between Betula pendula and Betula pendula ’Purple Rain’.The soluble protein content of Betula pendula ’Purple Rain’ was increased 168.31%,but the soluble sugar content of Betula pendula ’Purple Rain’ was decreased 45.24%respectively compared to those of Betula pendula.The photosynthsis of Betula pendula ’Purple Rain’ was inferior to that of Betula pendula.The light saturation point,light compensation light,carboxylation efficiency,maximum net photosynthetic rate,actual photochemical efficiency of PSⅡ and photochemical quenching of Betula pendula ’Purple Rain’ were decreased 16.24%,35.60%,44.52%,28.24%,33.46%and 23.02%respectively compared to those of Betula Pendula.The growth of Betula pendula ’Purple Rain’ was inferior to that of Betula pendula.The height and diameter at breast height of Betula pendula ’Purple Rain’ were decreased 7.52%and 19.78%respectively compared to those of Betula pendula.These data revealed that the decrease of photosynthsis may have contributed to the decrease of growth in Betula pendula ’Purple Rain’.In the present study,we compared differences between transcriptomes of Betula pendula and Betula pendula ’Purple Rain’ using Solexa sequencing technology.Short reads were assembled into unigenes,taking the distance of pair-end reads into account.All of the sequences were assembled,yielding 78157 non-redundant unigenes.Approximately 51.61%of the unigenes were annotated by Blastx and Blastn against six public databases(Nr,Nt,Swiss-Prot,KEGG,COG and GO),with a threshold of 10-5.Transcriptome data revealed numerous changes in gene expression attributable to the change of leaf color,which resulted in the upregulation of 3662 unigenes and the downregulation of 3351 unigenes.GO enrichment analysis revealed that 41 GO categories were significant differences between Betula pendula and Betula pendula ’Purple Rain’ including defense response,extracellular region and transferase activity.KEGG pathway analysis revealed that 22 pathways were significant differences between Betula pendula and Betula pendula ’Purple Rain’ including plant-pathogen interaction,stilbenoid,diary lheptanoid and gingerol biosynthesis and phenylpropanoid biosynthesis.Transcriptome analysis revealed that 50 genes involved in biosynthesis and regulation of anthocyanin and Calvin cycle were altered may have contributed to phenotypic changes.According to RNA-Seq results,BpCHS,BpDFR and BpMYB families were selected to research for gene expression in organs of BetulaPendula ’Purple Rain’ in one year old and two years old.BpCHS family genes expressed in leaf,petiole,root and stem of Betula pendula’Purple Rain’ in one year old.Among them,BpCHS1 and BpCHS3 were strongly expressed in leaf and BpCHS2 were strongly expressed in root.The expression of BpCHS3 was from strong to weak as the leaf color altered from purple to green in Betula pendula ’Purple Rain’ in one year old and two years old.BpDFR family genes expressed strongly in root,stem and petiole than that in leaf of Betula pendula ’Purple Rain’ in one year old.The expression of BpDFR5 was from strong to weak as the leaf color altered from purple to green in Betula pendula’Purple Rain’ in one year old and two years old.The expression of BpMYB family genes was inconsistent in Betula pendula ’Purple Rain’ in one year old.Among them,BpMYB2,BpMYB4 and BpMYB 11 were strongly expressed in leaf and BpMYB1,BpMYB6,BpMYB9 and BpMYB10 were strongly expressed in root,stem and petiole.The expression of BpMYB11 was from strong to weak as the leaf color altered from purple to green in Betula pendula ’Purple Rain’ in one year old and two years old.These data revealed that the expression of BpCHS3,BpDFR5 and BpMYBll may be connected with anthocyanin accumulation in leaf of Betula pendula ’Purple Rain,.In salt stress,the relative growth yield,salt damage index,chlorophyll content,anthocyanin content,chlorophyll fluorescence parameters of Betula pendula ’Purple Rain’were superior to those of Betula pendula.Cluster analysis revealed that related genes were upregulated in 3rd day in Betula pendula,whereas related genes were upregulated in 9th day in Betula pendula ’Purple Rain’ in salt stress.In drought stress,the drought damage index and chlorophyll content of Betula pendula ’Purple Rain’ were superior to those of Betula pendula,and the relative growth yield,anthocyanin content and chlorophyll fluorescence parameters of Betula pendula ’Purple Rain’ were inferior to those of Betula pendula.Cluster analysis revealed that related genes were upregulated in 3rd and 6th days in Betula pendula,whereas related genes were upregulated in 3rd day in Betula pendula ’Purple Rain’ in drought stress.These data revealed that Betula pendula cPurple Rain’ was highly adaptable than Betula pendula in salt stress but not good in drought stress.