Abstract
Auxin response factor (ARF) is a transcription factor that can specifically bind to the promoter of auxin-responsive genes in plants and plays an important regulatory role in plant growth and development. The previous studies have predicted 25 ARF genes in Sorghum bicolor (SbARFs) and indicated that SbARFs play complex roles in salt and drought stresses. In this study, we reclassified and analyzed the structures of ARFs in three plants, including sorghum, rice, and Arabidopsis. Phylogenetic analyses categorized 73 ARF into five classes. By studying the characterization of the structures, it was found that SbARFs from the same evolutionary branches showed similar motif patterns. Furthermore, the expression patterns of SbARF genes during development and temperature stress were investigated in sorghum. Quantitative transcription-quantitative polymerase chain reaction (qRT-PCR) results suggested that they had different expression patterns in vegetative and reproductive organs at various developmental stages. High and low-temperature treatments and qRT-PCR demonstrated some of them changed dramatically along with the increase of treatment time. Additionally, in situ hybridization results displayed that SbARF genes were accumulated in vascular tissues under temperature stress. These findings provide evidence that SbARFs may play important roles in sorghum vegetative development, reproductive development, and auxin response to temperature stress.
Highlights
Auxin is known to be involved in the regulation of growth and development and abiotic stress response
Most Auxin response factor (ARF) proteins consist of three parts: An N-terminal B3-type DNA binding domain (DBD) that may recognize the auxin-response elements (AuxREs), a variable middle region that may play as an activation domain (AD) or repression domain (RD), and two C-terminal domains (CTD: domain III/IV)
We focused on the expression pattern of these SbARF genes during development and temperature stress in sorghum
Summary
Auxin is known to be involved in the regulation of growth and development and abiotic stress response. As an important family of proteins in auxin-mediated response, ARF can recognize the auxin-response elements (AuxREs) in the promoters of auxin-responsive genes and activate or repress their expression [1,2]. According to the characteristic of molecular structures, ARFs have been identified from different plant species, and their roles in auxin-related plant growth and development have been studied intensively. Later research has found that AtARF2 represses the cell division and expansion in many vegetative and floral organs [12]. It may serve as a molecular link with ABA-mediated regulation of seed germination, and root meristem and drought stress [13,14,15]. AtARF3 has confirmed the roles in self-incompatibility, gynoecium patterning, shoot apical meristem maintenance, organ polarity, and regeneration [7,16,17,18,19]
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