Introduction

Alternative Oxidase identified as AOX is substance comprising of diiron carboxylate that is present in plant material that combines with the ubiquinol for the reduction of oxygen into water molecules. As a terminal for the reduction process, the AOX facilitates the direct transfer of electrons for the oxidation process. The differences in the structure of the AOX antibody gene sequence is dependent on the molecular distinction influenced by the divergence of the AOX across different plant families. More often than not, the differences have implications on the role taken on dependent on the plant species. According to Pu et al. 2015 (p. 331 ), there are two patterns of expression of alternative oxidase which are AOX1 and AOX2 with the latter being absent in monocotyledonous plants.

Material and Method

In bread wheat, the supposed homeologeous AOX1 has been recognized and characterized as an important factor establishing connection between genomes with evolutional distance from the complex grass species and monocot rice. The BLAST tool availed in the URGI database has been used in the identification of the wheat homeologous. The tool established an enhanced and completed annotation of the genome sequence in wheat thus establishing the presence of the AOX1. In addition, subsequent to the identification, the tool enabled the designing of the primers for a magnification of the genomic DNA of the putative AOX1 sequences in the cultivated wheat. The CLC Main Workbench software was used in the analysis of the probable homeologous sequences AOX1 data sequences.

 

Results and Discussion

The possibility of the existence of the homeologous status of the AOX1 in wheat was confirmed following evidence of similar intron exon structure of the gene AOX in higher plants of the same family (Considine et al. 2002). The exon 2,3, and 4 were visible in the 1c and TaAOX1a genes were of similar conserved size to the other AOX gene in the family members of higher plants (57, 129 and 489 bp in that order in AOX1 genes were also in four exons-three introns gene structures). On the other hand, the TaAOX1bhas no introns and only one exon as seen in figure 1.

Fig.1: A Schematic drawing of TaAOX1 genomic structure showing intron-exon organization. It shown seven novel homeologous genes as well as the two known genes (AB078882.1, and AB078883.1) encoding Aox1 were identified in hexaploid wheat.

The expected TaAOX1b-2AL/2BL/2DL, TaAOX-6BL/6DL and TaAOX1a-2BL/2DL proteins comprise of 329-345 residues of amino acids. The alignment of the sequence of the putative amino acid are in close relation to OsAOX1 from rice displayed that all the genes contained residues of histidine and glutamate in addition to four ?-helix regions as indicated in figure 2.

Fig. 2. Alignment of the deduced amino acid sequences of orthologous Aox1 proteins Arabidopsis, Rice, and Wheat in the region bounded by IBSs. Identical amino acid residues are shown on dots. The Red asterisks indicate the conserved iron-binding residues (conserved Glu and His residues) that act as iron ligands. Blue asterisks indicated the regulatory cysteine residues. Four ?-helical regions proposed in the current AOX model are highlighted in purple, which indicated iron-binding motifs (McDonald et al., 2003).

The analysis of the expression of the three AOX1 gene families contained in wheat by qRT-PCR exposed that they are made as a response to the inhibitors of the transport chain of electrons e.g. antimycin A figure 3 and 4 and potassium cyanide, data not shown.

Fig.3: Phylogenetic tree of alternative oxidases1 (AOX1) in Arabidopsis, Rice, and Wheat.

Figure 4. Expression of AOX1 genes under  antimycin A

 

 

 

 

Conclusion

From the information provided above, the phylogenetic relationship in the AOX protein indicates a possible monophyletic origin. The AOX in the plant indicate the role of the homodimer in the release of selective pressure within the conservation of gene sequences or the structural requirements for the regulation of the physiological process influenced by the stress in the environment (Pu et al. 2015 p. 337). Thus, the presence of the gene indicates similarities an as possible relation in the role played by AOX in the plant (Costa et al. 2014 p. 176).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bibliography

Considine MJ, Holtzapffel RC, Day DA, Whelan J, Millar AH (2002) Molecular distinction

between alternative oxidase from monocots and dicots. Plant Physiol 129: 949–953.

Costa, J.H., McDonald, A.E., Arnholdt-Schmitt, B. and de Melo, D.F., 2014. A classification

scheme for alternative oxidases reveals the taxonomic distribution and evolutionary

history of the enzyme in angiosperms. Mitochondrion, 19, pp.172-183.

Pennisi, R., Salvi, D., Brandi, V., Angelini, R., Ascenzi, P. and Polticelli, F., 2016. Molecular

Evolution of Alternative Oxidase Proteins: A Phylogenetic and Structure Modeling

Approach. Journal of molecular evolution, 82(4-5), pp.207-218.

Pu, X.J., Lv, X. and Lin, H.H., 2015. Unraveling the evolution and regulation of the alternative

oxidase gene family in plants. Development genes and evolution, 225(6), pp.331-339.