Abstract
The BES1 transcription factor family has an important role in the biosynthesis of brassinosteroids. It is a steroid
hormone that affects plant growth and development processes and the mechanism of response to environmental stresses. The
aim of this study was to determine the expression profiles of BES1 transcription factor in different tissues of sorghum
[Sorghum bicolor (L.) Moench] by applying different nitrogen sources (controlled fertilized, ammonia, nitrate and urea) and
to characterize BES1 gene family members through in silico methods. In sorghum genome, 9 Sobic-BES1 proteins with
amino acid numbers ranged from 190 and 716, molecular weights between 35.27 and 80.54 kDa and isoelectric points
between 5.0 and 10.07 were determined. In gene structure analysis, the number of estimated exons ranged from 2 to 10.
Phylogenetic relationship was determined using BES1 proteins of S. bicolor, Arabidopsis thaliana and Oryza sativa species.
Sobic-BES1-4 and Sobic-BES1-9 genes were found to be segmental duplicated in the evolutionary process. According to the
silico gene expression analysis, the expression levels of Sobic-BES1-4 and -9 genes were the highest in the root and shoot
tissues where different nitrogen sources and irrigation control were applied. On the other hand, the expression levels of
Sobic-BES1-1, Sobic-BES1-2 and Sobic-BES1-8 genes were differed according to the nitrogen source and tissue used. The
results of this study will provide a basis for functional gene research and contribute to the understanding of the BES1 gene
family in Sorghum bicolor.