DNA methylation of SlyAHL mediated by Fol-milR1 confers resistance to Fusarium wilt disease in tomato

Abstract Tomato ( Solanum lycopersicum ) is a nutrient-rich vegetable crop widely cultivated worldwide. Tomato Fusarium wilt disease caused by Fusarium oxysporum f.sp. lycopersici ( Fol ) is a soil-borne fungal disease that leads to enormous economic losses in tomato agricultural production worldwide. The latest research on small RNA (sRNA)-mediated DNA methylation (RdDM) has highlighted its role in plant disease resistance; however, the fungal pathogen cross-kingdom sRNA that mediates host DNA methylation to counteract tomato Fusarium wilt disease has not been explored. Previously, we documented that Fol -milR1, an sRNA effector, was transported into tomato cells during the pathogen infection and hijacked the tomato immune system by binding to SlyAGO4a . Here, we further explore how Fol -milR1-SlyAGO4a participates in resistance to Fusarium wilt by regulating the DNA methylation of disease-resistant genes in tomato. The Fusarium wilt-susceptible tomato cultivar Moneymaker was infected with the water/ Fol -WT/ Fol -milR1_KO strain, followed by whole-genome methylation sequencing. The methylation level of Solyc08g080960 ( SlyAHL ) was associated with Fol -milR1 expression in tomato. The methylation type was mainly CG in the SlyAHL coding region. SlyAHL was required for wilt disease resistance by regulating reactive oxygen species (ROS) accumulation in tomato. In summary, the Fol- milR1 -SlyAGO4a-SlyAHL function module, which mediates resistance to tomato wilt disease, provides a potential environmentally friendly strategy to manage it.