Functional characterization of fatty acyl-CoA reductase gene RcFAR1 and its insect resistance in callus of Rosa chinensis

This study aims to investigate the molecular mechanism underlying the resistance of rose (Rosa chinensis) to the beet armyworm (Spodoptera exigua) induced by powdery mildew (Podosphaera pannosa) infection, and to clarify the function of the fatty acyl-CoA reductase gene RcFAR1 in this process.Bioinformatic methods were employed to identify and analyze the RcFARs gene family in rose. The RcFAR1 gene, which is up-regulated upon powdery mildew infection, was cloned using RT-PCR. It was then transformed into rose callus via Agrobacterium-mediated transformation to obtain callus overexpressing RcFAR1. Gas chromatography-mass spectrometry (GC-MS) was used to detect changes in fatty alcohol content in the positive callus. An oviposition bioassay was conducted to analyze the effect of the transgenic callus on the oviposition choice of female S. exigua moths.The results showed that all members of the rose RcFARs family possess the typical conserved FAR domain. The contents of 1-hexadecanol and 1-octadecanol were significantly accumulated in the RcFAR1-overexpressing callus. Female S. exigua moths showed a significant oviposition preference for control callus transformed with the empty vector, with an oviposition repellent rate of 45% against the transgenic callus.RcFAR1 mediates pathogen-triggered fatty alcohol biosynthesis, and its products act as olfactory signals to repel S. exigua oviposition. This study establishes a callus-based tripartite interaction model (plant-pathogen-insect), providing a simple and effective experimental system for deciphering plant-induced defense mechanisms. RcFAR1 represents a promising candidate target for the molecular breeding of insect-resistant rose.