Abstract: 【Objective】 A gene encoding MYB transcription factor, designated GmMYB111, was cloned, its basic biological functions and expression pattern were identified in soybean and yeast cells. 【Method】 A MYB transcription factor GmMYB111 was obtained from salt stress-related digital expression profiling (DGEP) data analysis. cDNA sequence of GmMYB111 was isolated and cloned using cDNA from soybean salt-treated roots by RT-PCR method. A homology search was performed using GmMYB111 protein sequence as a query, and protein sequences of high similarity with GmMYB111 from other species were obtained. Using MEGA5.05, multiple sequence alignments between GmMYB111 protein and its homologous ones from other species were done and a phylogenetic tree of homologous species was constructed. The induced expression and tissue-specific expression profiles of target genes in soybean with abiotic stress were detected by real-time fluorescent quantitative PCR. The subcellular localization of GmMYB111 was analyzed using Arabidopsisprotoplast transformation system, and its transcriptional activity and in vivo binding activity were determined by yeast hybrid system. 【Result】GmMYB111 gene, a significantly upregulated gene (27 folds) in response to salt stress, was obtained based on the preliminary digital expression profiling (DGEP) data related to salt stress in authors laboratory. Using RT-PCR method, fragment of this gene was cloned from cultivated soybean root. Sequence alignment revealed that its sequence was consistent with that from the published Williams82 genome database. Bioinformatics analysis indicated that the deduced amino acids had common characteristics of MYB transcription factors with two MYB domains of R2 and R3 at the N-terminal and an acidic amino acid-rich transcriptional activation domain at the C-terminal. Phylogenetic tree analysis suggested that the encoded protein had the closest genetic relationship with GmMYB76, GmMYB12a, and MtMYB61. The expression of GmMYB111 in soybean was induced by high salt, drought, chilling, and ABA treatments, respectively. Real-time fluorescent quantitative PCR detection results showed that the induced GmMYB111 was upregulated by high salt and cold stress, and was first upregulated and followed by a down-regulation by drought stress. There was a wave-like up- and down-regulated expression of GmMYB111 inducted by ABA treatment. Analysis of temporal and spatial expression showed that GmMYB111 was nearly expressed in all detected tissues, and its expression level was relatively high at seedling and low at maturing stage. From the perspective of different tissues, GmMYB111 showed the highest expression in stem, leaf, and flower, relatively low in root, and no expression in pod. Subcellular localization results showed that GmMYB111 was located in the nucleus which belongs to a typical transcription factor, yeast hybrid assay indicated that GmMYB111 had transcriptional activation functions and could bind to the cis-acting element TAACTG motif. 【Conclusion】GmMYB111 is a typical R2R3-MYB transcription factor, with transcriptional activation function and DNA binding activity. Its expression in soybean may be related to the abiotic stress and ABA signal transduction pathway. GmMYB111 is speculated to regulate the soybean response to abiotic stresses by regulating the expression of downstream genes.

Key words: soybean, GmMYB111, expression analysis, binding motif, transcriptional activation activity