A miR858 variant negatively regulates resistance to tea leaf spot through targeting the CsMYB1-CsPME41 module

In recent years, tea leaf spot, caused by the fungus Epicoccum sorghinum, adversely affects both the yield and quality of tea in China. Transient overexpression and antisense oligonucleotide (AsODN) assays revealed that upregulating CsMYB1, a transcription factor located in the nucleus, enhances resistance to E. sorghinum infection in tea leaves. Overexpression of CsMYB1 in transgenic Nicotiana benthamiana conferred resistance to Botrytis cinerea. Multi-omics assays of transiently overexpressed CsMYB1 in tea leaves indicated that CsMYB1 induces the expression of numerous disease resistance genes. DNA affinity purification sequencing assay indicated that CsMYB1 can activate the expression of the disease resistance gene pectinesterase/pectinesterase inhibitor 41 (CsPME41). β-glucuronidase and dual-luciferase assays showed that csi-miR858-3p_L-1 targets and cleaves CsMYB1. Moreover, transient overexpression and AsODN assays in tea leaves and transgenic csi-miR858-3p_L-1 N. benthamiana plants indicated that increasing csi-miR858-3p_L-1 levels heightens susceptibility to E. sorghinum in tea leaves. The relative expression levels of CsMYB1, CsPME41, and csi-miR858-3p_L-1 in tea leaves exhibited distinct spatial and temporal patterns in response to E. sorghinum invasion. This study reveals that the csi-miR858-3p_L-1-CsMYB1-CsPME41 module plays a role in the disease resistance response of tea plants to E. sorghinum infection, providing crucial data for resistance breeding.