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 LOXs 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 Coffea arabica. We found 18 LOX genes in Coffea arabica and 9 genes each in Coffea eugenioides and Coffea canephora. Chromosomal localization analyses revealed strong correspondence between the LOX genes of tetraploid Coffea arabica and those of its putative diploid progenitors, Coffea eugenioides and Coffea canephora. Transcriptomic and enzymatic analyses showed that hexanoic acid application modulates the expression of specific LOX genes and alters LOX activity in leaves and roots of Coffea 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 Coffea arabica represents promising candidates for detailed functional analyses, as they likely contribute substantially to LOX activity and elicitor-induced defense responses in Coffea species.