Isolation And Characterization Of Brassinosteriod Biosynthesis Gene DET2 In Poplar

Brassinosteriods as essential plant hormones play crucial roles in plant growth and development.Brassinosteriods play impotent roles in cell division and elongation.DET2,a5?-reductase,is considered to catalyze a major rate-limiting in brassinosteriods biosynthesis.Study on PagDET2 gene is useful to understand the role of brassinosteriods in woody plants.In this study,.trees in pots were treated by applying BL or a BR biosynthesis inhibitor(PCZ)to observed the influences of stem growth and xylem formation.PagDET2,a homologus gene of Arabidopsis At DET2,was isolated from 84K(Populus alba × P.glandulosa,‘84K').Bioinformatic method was used to sequence alignment and analyze the basic physical,chemical characteristics and evolutionary relationship.Tissue expression patterns in poplar was analyzed by RT-PCR.The over-expression vector was constructed and transformed into 84 K poplar.PagDET2-OE and wild-type plants were used to measure the content of brassinosteriods in vivo and analyze the role of DET2 in plant growth and stresses resistance.Treated trees in pots by applying BL or a BR biosynthesis inhibitor(PCZ)could influences stem growth and xylem formation.BL treatment influences stem growth and xylem formation during secondary growth.Soil-applied BL can enhance poplar stem growth,but only within a concentration-dependent range.The BR biosynthesis inhibitor,propiconazole(PCZ),was used to examine the effect of lowered BR levels on poplar stem growthThe CDS of PagDET2 gene is 774 bp,encoding a 257 amino acid protein.The protein sequence PagDET2 protein are conserved among populus trichocarpa,Arabidopsis thaliana,rice,cotton,soybean and tomato.Tissue specific expression analysis showed that PagDET2 was detected in root,leaf tissue and stem tissue.Stem tissue of internode1 to 3 showed the highest expression level among these tissues.The brassinosteriods content of poplar was measured by ELISA.DET2 could significantly increase the endogenous brassinosteriods content of poplar.Overexpression of DET2 gene can promote plant growth and be more sensitive to salt stress.Overexpression of PagDET2,a rate-limiting gene in brassinosteriodsbiosynthesis,can significantly increase endogenous brassinosteriods content and increase plant growth.PagDET2 may also be involved in the wood formation and internode elongation.