Sequence Analysis of DET2 Gene In Different Gossypium Species

Brassinosteroids (BRs) are a class of plant steroidal hormones that are involved in a wide variety of physiological and developmental programmes. The first step in BR biosynthesis is catalyzed by a steroid 5a-reductase (DET2), and DET2 gene controls the level of BR. In cotton, DET2 gene (GhDET2) has been cloned in G. Gossypium (AADD tetraploid species). The genus Gossypium includes diploid species in eight genomic groups and five tetraploid species. In the evolution process, many genes sequences changed. So the research selected some diploid species and tetraploid species for tested materials to study the change of DET2 gene squence in the cotton evolution process. Based on the full-length gene cDNA sequence of DET2 in Genebank, we designed PCR primers to amplify DET2 gene, and its sequences in different cotton species were analysed. The results showed that DET2 gene was not only in A, D genomic species, but also in B, C genomic species, and there were high similarity among tested species. This indicated that DET2 gene in cotton in the evolution process had minor change, this gene might be an indispensability gene during cotton growth and development. The analysis of DET2 gene expression level in different cotton species showed that DET2 gene expression level of D genomic species was significantly higher than that of the other cotton species in AABAC genome. The results indicated that DET2 genes existed in all tested cotton species, but its importance in different species might be different. The research is propitious to understanding the change of DET2 gene during the cotton evolution, and provides more information of DET2 gene for improving cotton cultivars.