Study On The Regulation Mechanism Of BR On The Development Of Xylem Cells Of Eucalyptus Grandis

Brassinosteroid(BR)refers to a group of polyhydroxylated pant steroidal lactones involved in various developmental events,including embryogenesis,cell division,skotomorphogenesis,photomorphogenesis,vascular system differentiation,reproductive development,dan stress tolerance processes.In this study,Eucalyptus grandis clones of GL1 rooting with addition of Brassinolide and brassinolide inhibitor in culture medium(Brassinazole,BRZ)was found that brassinolide can promote the growth of seedling height,root and stem secondary growth,and increase the degree of lignification.BRZ has inhibitory effect on seedling height,significantly on the secondary growth of root and stem,and found that the two effects in rooting substrate will have offset the effect of applied substrate.At the same time,it was found that BR and BRZ had a promoting effect on the formation of xylem cells,and the effect was more significant when they were smeared on the surface layer.The interaction between BR and GA was studied in tissue culture seedlings,showing that BR and GA also applied for plant growth promotion,with a remarkable increase the height and in the roots of seedlings lignification.On the contrary,smearing the two fertilizer synthesis inhibitor at the time was found outside the seedling height and xylem level decreased.The analysis is based on the observation of the quantitative key gene PCR on Synthesis of BR and the signaling pathway of DWF4,BRI1 and BZR1,as well as differential expression analysis among the HD-ZIPIII family members PHV,PHB,ATHB15 gene and the regulation of lignin biosynthesis transcription factor VDN6 and SND1 expression;in addition,in order to study the application of BR is the interaction with other hormone such as auxin,cytokinin,in this study the auxin,cytokinin,gibberellin,abscisic acid,ethylene,SHI,SUR2 response genes OPR2,IPT3,GA20OX1,DELLA1,ABA2,MoCo,DAD1 gene differential expression analysis.It was found that cytokinin and gibberellin had a positive response to the topdressing of brassinolide,and the expression of VND6 and DWF4 was also increased significantly.The results showed that the control of Brassinolide on plant growth was mediated by multiple hormones,but also confirmed that the brassinolide on the development of xylem has a regulatory role.To further explore the brassinolide to lay the foundation for the molecular wisdom of wood formation.