Genome-wide identification and expression analysis of lipoxygenase genes in Tartary buckwheat

Lipoxygenases (LOXs; EC1.13.11.12) are widely involved in plant growth, development, maturation, senescence and stress resistance. LOXs have been studied in many crop species but not in Tartary buckwheat [Fagopyrum tataricum (L.) Gaertn.]. This study aimed to systematically identify and analyze LOX genes in Tartary buckwheat. Eight LOX genes, which were unevenly distributed on five chromosomes, were identified in the Pinu1 Genome database. The data indicated that during long evolution, FtLOX genes were subjected to purifying selection. The conservation of motifs within the 9-LOX and 13-LOX subfamilies supported the results of phylogenetic analyses. All FtLOX proteins contained the LOX family-specific His-(X)₄-His-(X)₄-His-(X)₁₇-His-(X)₈-His motif, suggesting that this motif is essential for protein function. Analyses of physical and chemical properties showed that FtLOX6 might function under both acidic and alkaline conditions. The FtLOX gene promoters contained many light-responsive elements, and transcriptome data further suggested their roles in growth regulation and the response to light. Quantitative real-time polymerase chain reaction analysis of expression differences in plants exposed to different wavelengths of light confirmed that FtLOX1 and FtLOX4–7 could respond to light. Genes co-expressed with FtLOX genes were involved in the photoreaction-related pathway. This study provides a basis for further functional research in order to better understand the biological role of individual LOX gene in Tartary buckwheat.