The Molecular Characteristics of Soybean ARR-B Transcription Factors

The Type-B authentic response regulator (ARR-Bs) gene family is one of the important plant-specific transcription factor families involved in variety of physiological processes. However, study of ARR-Bs gene family in soybean is limited. Genome-wide analysis and expression profiling of the ARR-Bs gene family were performed in the soybean genome. 31 ARR-Bs genes (namely GmARR-B1-31) were identified, containing conserved catalytic domains with protein lengths and molecular weights ranging from 246 to 699 amino acids (aa) and 28.30 to 76.86 kDa, respectively. Phylogenetic analysis grouped ARR-Bs genes into three clusters-Cluster I, Cluster II, and Cluster III- which included 15, 12, and 4 genes, respectively, and were asymmetrically distributed on 17 chromosomes. Tissue specific expression analysis of GmARR-Bs family revealed a high transcription level in flowers, roots and seeds. The subcellular localization of GmARR5, GmARR14 were observed in the nucleus, and the promoter region of them included low-temperature responsive element (LTR), the C-repeat/dehydration responsive element (DRE), MBS, ABRE, MYB, MEJA and TCA-elements, which possibly participate in abiotic stress and hormones responses. qRT-PCR analysis showed that the expression of GmARR-B genes were affected by different abiotic stresses, especially cold stress and salt stress, and GmARR-B5 and GmARR-B14 were significantly induced by cold stress. This suggested that ARR-Bs genes were involved in multiple abiotic stress response pathways and acted as a positive factor under cold stress.