The Mechanism Involved in High-Lycopene Tomato Mutants for Broomrape Resistance

This is the authors' abstract. We don't add key points for this paper.

The root parasitic weed Phelipanche aegyptiaca (Pers.) Pomel poses a serious threat to solanaceous crops, leading to yield losses of up to 80% in tomato (Solanum lycopersicum L.). Strigolactones (SLs), derived from the carotenoid metabolic pathway, serve as key host-recognition signals for root-parasitic plants. This study investigated the molecular mechanisms of host resistance, focusing on the suppression of SL biosynthesis through altered carotenoid metabolism in the high-pigment tomato mutants hp-1 and ogc. Both pot experiment and in vitro seed germination assays demonstrated that the mutants exhibited reduced susceptibility to P. aegyptiaca and triggered lower germination rates in broomrape seeds compared to the wild-type cultivar AC. Quantitative RT-PCR analysis revealed a significant downregulation of SL biosynthesis genes (SlD27, SlCCD7, SlCCD8, SlMAX1, SlP450, SlDI4) in hp-1 at various parasitic stages post-inoculation, with a more pronounced suppression observed in hp-1 than in ogc. Notably, the extent of downregulation correlated with the enhanced resistance phenotype in hp-1. These findings highlight a synergistic resistance mechanism involving the coordinated regulation of carotenoid metabolism and SL biosynthesis, providing new insights into the molecular defense network underlying tomato-broomrape interactions.