Molecular, in silico and expression studies on lipoxygenases (LOXs) in potato (Solanum tuberosum L.)

Lipoxygenases (LOXs) namely 9-LOXs and 13-LOXs catalyse the oxygenation of polyunsaturated fatty acids to produce fatty acid hydroperoxides which are crucial in growth, development and stress responses in plants. Here, we isolated and characterized a 2723-bp cDNA encoding a distinct 861-aa 9-LOX form, designated StKCLX-1, using tuber total RNA from an Indian potato cultivar, Kufri Chipsona-1 through RT-PCR. A total of 17 LOX genes distributed in different chromosomes were identified and characterized in the potato genome. Multiple sequence alignment revealed highly conserved amino acids in the crucial domains, motifs and variable N-terminal regions between the LOX classes. A total of 36 LOXs from potato, tomato and Arabidopsis were used in phylogenetic analysis. A 3-D structure of StKCLX-1 was predicted by AlphaFold tool, validated through the predicted local-distance difference test (pLDDT) and Ramachandran Plot. Molecular docking predicted the nature of receptor-ligand interactions. STRING database was used to predict the protein-protein interactions. Expression patterns of the LOXs in the potato organs were examined by Expression Atlas and semi-quantitative RT-PCR. 9-LOX activity was noticed at early stages of tuberization, and significantly increased in the freshly-harvested mature tubers. This report would be useful in gaining insights into the structure-function relationships of the LOXs and corresponding multigene family-prerequisites for understanding tuber development in potato.