Analysis of the ACP Gene Family in Sorghum Supports a Connection with Stress Tolerance
Acyl carrier proteins (ACP) are involved in fatty acid synthesis, and in plants’ growth, development, metabolism, and adaptation to stress. Although the assembly of the whole genome has been completed in sorghum as well as in multiple other plants, such as Arabidopsis and soybean, a genome-wide analysis of the ACP gene family in sorghum had not been conducted. Further investigation into ACP is of interest to scientists, breeders and growers.
In an effort to deepen their understanding of ACPs in sorghum, Ge and colleagues from Nantong University and Nantong Changjiang Seed Co., analyzed the sorghum ACP gene family and investigated the ACPs expression patterns under abiotic stresses. In the sorghum genome, nine ACP family members, located on chromosomes 1, 2, 5, 7, 8 and 9, were identified. Using multi-sequence alignment, the researchers showed that key regions have a high degree of conservation whereas other sections vary. This variation is likely the result of evolutionary events which altered the gene structure and function of specific SbACP family members. When the SbACP gene family was compared to that of maize, rice and Arabidopsis using phylogenetic tree analysis, the closer evolutionary relationship of maize and rice with sorghum was supported. The gene structure and conserved motif of SbACP5 and SbACP7, which shared a large fragment replication and thus were in the same branch of the evolutionary tree, were virtually identical. However, they had different response patterns to drought and salt treatment, which the researchers hypothesize, could be do to functional redundancy or differences in their cis-acting elements. Collinearity analysis revealed that 10% of the colinear genes were found throughout the genome, but within the SbACP family there was no tandem duplication, and there was only minor fragment replication, suggesting that most SbACPs are the product of relatively independent evolution events.
Subcellular localization of SbACPs was predicted to be mainly distributed in chloroplasts and mitochondria. However a tobacco transient localization assay showed SbACPs being mainly localized in chloroplasts. The three-dimensional structure prediction conducted in the study showed that protein sequences were highly conserved among the different ACP branches, supporting previous research. The promoter regions upstream of SbACPs were also analyzed; cis-acting elements in the gene promoter region regulate gene expression. The analysis showed that the SbACPs could potentially have a diverse array of functions, including light response, plant growth and development regulation, biotic and abiotic stress response, and plant hormone regulation. Further investigation, using qRT-PCR analysis, indicated the involvement of SbACPs in adaptive regulation to abiotic stresses like drought and high salinity, hinting at a connection between fatty acids and stress tolerance in sorghum. Out of the nine SbACP genes, all except SbACP4 and SbACP8 had different expression patterns in response to salt or water stress. In fact, SbACP9 was up-regulated 6 to 24 hours after water stress, showing such a strong response that the researchers feel it might have a direct connection to drought tolerance. The analysis of ACP genes in sorghum could assist future research into the function of SbACP genes and the genetic selection of stress-tolerant sorghum.
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Reference
Ge H, Xu J, Hua M, An W, Wu J, Wang B, Li P, Fang H. Genome-wide identification and analysis of ACP gene family in Sorghum bicolor (L.) Moench. BMC Genomics. 2022 Jul 25;23(1):538. PMID: 35879672. DOI: 10.1186/s12864-022-08776-2. Read more
