Function Analysis Of BpBEE Gene In Betula Platyphylla

Brassinolide Enhanced Expression (BEE), which have encoded the characteristic bHLH transcription factors in plant, be involved in Brassinolide signal transduction. To analysis the functions of BpBEE2 in Betula platyphylla, plant overexpressing vector and suppressing vector were constructed, and were transformed into birch using Agrobacterium-mediated system, plant growth, salt and drought-tolerance of transgenic lines were analyzed. This study is composed of the following aspects:1. Three BpBEE genes were obtained from B. platyphylla base on birch transcriptome databases. Bioinformatics analyses showed that the genetic characteristics of BpBEEs were different, however, all gene have five introns, six exons in genome sequence, and the typical bHLH structure domain.2. Using real-time PCR, the expression patterns of three birch BpBEE genes were analyzed, the results showed that the genes were expressed in the leaves, female flowers, male flowers, stems and apical buds.All the three BpBEE genes expressed significantly higher in leaves than in others tissues. In the vigorously growing stage, BpBEE genes were up-regulated in leaves and bud, indicated that BpBEE genes may be involved in the growth process of birch. As for BR treatment, BpBEEl were significantly up-regulated in buds and xylems in the early stages; BpBEE2 was up-regulated in the xylems and phloems in early stage, and also increased in different degree in other stages. The results suggested that three BpBEE genes are involved in BR hormone response, BpBEE1 and BpBEE2 show early reply response.3. Plant overexpression vector containing BpBEE2 gene was constructed by Gateway technology and suppress vector was using enzyme linked methods, then transformed into birch via Agrobacterium tumefaciens-mediated. The transgenic plants were identified by PCR, the result showed that BpBEE2 gene was successfully integrated into the plant genome.We obtained one overexpression line and five suppression lines.4. Measured the growth of transgenic lines. The results showed that the growth over-expression was significantly higher than the wild type, while suppression expression lines was lower. Overexpression BpBEE2 gene can improved the plants growth.5. Birch transgenic and non-transgenic lines were implemented using 0.4%,0.6% NaCl and 5%,10% PEG stress treatment, fresh weight and rooting rates were to complie statistics, the results showed that transgenic lines were not significantly improved the resistance of salt and drought.6. Based on genome information of B. Platyphylla, a 1750 bp flanking sequence upstream of BpBEE1 gene was cloned, and constructed into plant expression vector, and was transferred into Arabidopsis, then investigated the expression pattern via histechemical GUS staining. Cis-regulatory elements was analyzed, some response elements of hormones were contained in the promoter. Histechemical GUS staining showed that leaf veins with obvious GUS expression were found in transgenetic Arabidopsises. GUS expression was stronger under MeJA treatment in transgenic line.IAA and ABA reduced the GUS activity in transgenic line.The results were same as GUS staining.