Jasmonatos en frutilla (Fragaria x ananassa): caracterización fisiológica y molecular de los componentes de la vía de biosíntesis y señalización, y análisis estructura-función de los represores JAZ

Abstract

Jasmonates (JAs) are phytohormones regulating stress responses and developmental processes. The role of JAs is well known in Arabidopsis, in which they control flavonoid compounds accumulation like anthocyanins, through regulation of their biosynthesis and signaling pathways. Specifically, JASMONATE ZIM-DOMAIN (JAZ) proteins are central repressors of the JA-signaling pathway by protein-protein interactions, and these proteins also regulate transcription factors (FTs) of MYB-bHLH-WD40 (MBW) complex related to proanthocyanidin (PAs) and anthocyanin biosynthesis. However, JAs role in non-climacteric fruits like strawberry is unknown. The aims of this thesis were to elucidate JAs levels during development and ripening of strawberry (Fragaria × ananassa Duch.) fruits, and the conservation of JA signaling pathway components, as well as repressor activity of JAZ proteins on key members of JA-signaling pathway and MBW complex by protein-protein interactions. For this purpose, JAs content changes were evaluated during F. × ananassa fruit development; genes and proteins of JA-signaling pathway were characterized in Fragaria vesca L., and protein-protein interactions between JAZ and components of JA-signaling pathway and MBW complex were studied in F. × ananassa. JA contents showed higher levels at flowering and early stages of fruit development, and next, levels decreased to ripening, accompanied of downregulation of JA metabolism-related gene expression. In F. vesca, JAZ and MYC2 encoding genes were characterized and their expression exhibited a decreasing profile similar to JA levels in F. × ananassa. JAZ and MYC2 showed high conservation level in structural domains at protein level, respect to their analysed orthologs. Protein-protein interactions showed conservation of JAZ molecular targets, which belonging to JA signaling pathway, indicating a functional conservation for this pathway in strawberry. Besides, a new non-canonical degron sequence for FaJAZ1 was identified, which showed functionality for JA perception, mediated by coronatine. Finally, JAZ repressors also interacted with TFs of MBW complex, bHLH3-2, bHLH33-2, MYB10-2, related to PAs and anthocyanin biosynthesis in strawberry. Globally, these results suggest that JAs would have a functional role at early development stages of strawberry fruits, a functional conservation of JA-signaling and a regulator role of JAZ repressors on TFs related to PAs and anthocyanin biosynthesis in F. × ananassa.