Abstract

The phytohormone jasmonoyl-isoleucine (JA-Ile) regulates fundamental plant processes as developmental and defense responses. JA-Ile mediates the interaction between the F-box protein COI1 (part of the SCFCOI1 E3 ubiquitin ligase) and a JAZ repressor leading to early jasmonate responses. The Arabidopsis JAZs proteins contain a degron sequence, which is responsible for the stabilization of the COI1-JA-Ile-JAZ complex. In strawberry (Fragaria ×ananassa) JAZ family was described at transcriptional level during fruit development but the information about the interaction mode of this complex is still scarce at molecular level. To gain insight into the strawberry JA-Ile receptor complex, we evaluated the interaction at structural level, and protein models were built and analyzed for FaCOI1 and FaJAZ1, FaJAZ8.1 and FaJAZ10. The interaction between FaCOI1 and FaJAZ1, FaJAZ8.1 and FaJAZ10 were explored using several ligands, through molecular docking and molecular dynamics (MD) simulations, finding the strongest interaction with (+)-7-iso-JA-Ile than other ligands. Additionally, we tested interactions between FaCOI1 and FaJAZs by yeast two-hybrid assays in the presence of coronatine (COR, a JA-Ile mimic). We detected strong COR-dependent interactions between FaCOI1 and FaJAZ1, which have a new non-canonical (IPMQRK) degron sequence. Phylogenetic analysis showed that the new IPMQRK degron is only present in orthologs belonging to the Rosoideae but not in other Rosaceae subfamilies. Together, this study uncovers a new degron sequence in plants, which could be required to make an alternative and functional JA-Ile perception complex in strawberry