Genome-wide analysis of lipoxygenase genes in Coffea arabica and its diploid progenitors

Lipoxygenase proteins (LOXs) play a crucial role in plant growth, development, and defense notably through their involvement in jasmonic acid (JA) biosynthesis. Here, we aimed to identify and characterize genes encoding lipoxygenases in three coffee species, Coffea arabica, Coffea canephora, and Coffea eugenioides, and to evaluate whether LOX genes are differentially expressed following hexanoic acid application in C. arabica. We found 18 LOX genes in C. arabica and 9 genes each in C. eugenioides and C. canephora. Chromosomal localization analyses revealed strong correspondence between the LOX genes of tetraploid C. arabica and those of its putative diploid progenitors, C. eugenioides and C. canephora. Transcriptomic and enzymatic analyses showed that hexanoic acid application modulates the expression of specific LOX genes and alters lipoxygenase activity in leaves and roots of C. arabica cvs. Catuaí Vermelho and Obatã. Notably, three LOX genes displayed strong correlations between transcript abundance and enzymatic activity. Together, these results indicate that a subset of LOX genes in C. arabica represents promising candidates for detailed functional analyses, as they likely contribute substantially to lipoxygenase activity and elicitor-induced defense responses in Coffea species.