Understanding the Role of Auxin Carrier Genes under Biotic and Abiotic Stresses in L.

The PIN-FORMED (PIN) proteins represent the most important polar auxin transporters in plants. Here, we characterized the gene family in two olive genotypes, the subsp. var. and the var. (cv. 'Farga'). Twelve and 17 genes were identified for vars. and , respectively, being distributed across 6 subfamilies. Genes encoding canonical OePINs consist of six exons, while genes encoding non-canonical OePINs are composed of five exons, with implications at protein specificities and functionality. A copia-LTR retrotransposon located in intron 4 of of var. and the exaptation of partial sequences of that element as exons of the of var. reveals such kind of event as a driving force in the olive evolution. RNA-seq data showed that members from the subfamilies 1, 2, and 3 responded to abiotic and biotic stress factors. Co-expression of with genes involved in stress signaling and oxidative stress homeostasis were identified. This study highlights the importance of genes on stress responses, contributing for a holistic understanding of the role of auxins in plants.