Systematic analysis of NAC transcription factors’ gene family and identification of post-flowering drought stress responsive members in sorghum
SbNAC genes (131) encoding 183 proteins were identified from the sorghum genome and characterized. The expression patterns of SbSNACs were evaluated at three sampling time points under post-flowering drought stress.
NAC proteins are specific transcription factors in plants, playing vital roles in development and response to various environmental stresses. Despite the fact that Sorghum bicolor is well-known for its drought-tolerance, it suffers from grain yield loss due to pre and post-flowering drought stress. In the present study, 131 SbNAC genes encoding 183 proteins were identified from the sorghum genome. The phylogenetic trees were constructed based on the NAC domains of sorghum, and also based on sorghum with Arabidopsis and 8 known NAC domains of other plants, which classified the family into 15 and 19 subfamilies, respectively. Based on the obtained results, 13 SbNAC proteins joined the SNAC subfamily, and these proteins are expected to be involved in response to abiotic stresses. Promoter analysis revealed that all SbNAC genes comprise different stress-associated cis-elements in their promoters. UTRs analysis indicated that 101 SbNAC transcripts had upstream open reading frames, while 39 of the transcripts had internal ribosome entry sites in their 5′UTR. Moreover, 298 miRNA target sites were predicted to exist in the UTRs of SbNAC transcripts. The expression patterns of SbSNACs were evaluated in three genotypes at three sampling time points under post-flowering drought stress. Based on the results, it could be suggested that some gene members are involved in response to drought stress at the post-flowering stage since they act as positive or negative transcriptional regulators. Following further functional analyses, some of these genes might be perceived to be promising candidates for breeding programs to enhance drought tolerance in crops.
KeywordsNAC Drought Sorghum bicolor (L.) Moench Phylogenetic tree Gene expression
This study was supported by Agricultural Biotechnology Research Institute of Iran (Project Number: 3-03-0305-93122), Education and Extension Organization (AREEO). University of Guilan and the Ministry of Science, Research and Technology are also acknowledged for supporting the project. The authors are grateful for the kind cooperation of Dr. Azim Khazaei and Mr. Mojtaba Jowkar (to plant culture in the field), Dr. Behzad Sorkhi (to provide real-time PCR facility) and Mr. Mohammad Jedari (to create the artworks).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflicts of interest.
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