Cloning And Functional Analysis Of OsBRI1 Promoter In Rice

Brassinosteroids(BRs) are a class of plant polyhydroxysteroids that have been recognized as a new kind of phytohormones that play an essential role in plant development. Since the discovery of BL in 1979, more than 70 BRs have been isolated. Among all naturally occurring BRs, CS and BL are the most important BRs because of their wide distribution as well as their potent biological activity. In addition to the completion of the major gap in the BR signaling by understanding how BR signals are transmitted from the plasma membrane to the nucleus in Arabidopsis, the subcellular compartmentalization and trafficking of BR receptor complexes was introduced as an integral part of the BR signal transduction. It perceives and transmits signals through transmembrane receptor protein kinase BRI1, which is located on the cell membrane. Previous studies have indicated that AtBRI1 was widely expressed in Arabidopsis thaliana, but the expression of OsBRI1 in rice roots was not obvious. Therefore, the expression of BRI1 in rice and Arabidopsis were different. So this was caused by the gene itself or due to the differences in the promoter region so that the gene had different expression patterns. In order to explore the reason, we compared the BRI1 gene sequences of Brassicaceae and Gramineae and found that the coding gene of BRI1 was conservative, and the promoter region had diversity. So it is inferred that the polymorphism of promoter region may result in the different expression of BRI1 protein in rice and Arabidopsis thaliana. Therefore, we cloned the OsBRI1 promoter and compared the differences in the expression patterns of transformed Arabidopsis thaliana.The main results of the experiment are as follows:1. BRI1, between Brassicaceae and Gramineae, coding gene and promoter sequence alignment showed that coding sequences of BRI1 are conserved between the two families and promoter sequences have diversity.2. Bioinformatics analysis of the rice OsBRI1 start subsequence of cis-acting element, found the sequence containing multiple promoter is a basic component of the TATA box and CAAT box, and contains a variety of hormone response element such as CGTCA-motif, TGACG-motif, ABRE and TGA-element, adversity stress response elements(MBS, HSE, TCT-motif and CCAAT-box) and many other cis-acting element about light such as G-box, Sp1, GAG-motif..3. pOsBRI1 promoter was cloned by the PCR technology using specific primers. The pOsBRI1::GUS vectors were constructed and transformed into the Arabidopsis thaliana.4. GUS staining showed that OsBRI1 promoter and AtBRI1 promoter modes are no significant difference in expression. Just in the roots, OsBRI1 promoter does not have high expression in Arabidopsis, suggesting that may be due to some cis-acting element to regulate gene expression level.