The Genome Assembly of Cochliobolus heterostrophus Strain TM17 and the Identification of Virulent Secreted Protein ChTMSP2

Cochliobolus heterostrophus, the causal agent of southern corn leaf blight, poses a significant global threat to maize production. However, the molecular basis of its virulence in maize remains largely unknown. Here, we present an improved genome assembly of the Chinese isolate C. heterostrophus strain TM17, comprising 17 contigs with 12 assembled as gapless chromosomes. RNA-seq analysis across three stages (conidial, vegetative, and appressorial) enabled classification of 969 predicted secreted protein genes into four functional groups. Among these, the Group II secreted protein-encoding gene ChTMSP2 is transcriptionally induced during maize infection and shown to be essential for the virulence on maize. Disruption of ChTMSP2 significantly attenuates fungal virulence on maize. Importantly, this virulence mechanism operates independently of both cell death activation and suppression of INF1-mediated immunity. Collectively, the TM17 genome assembly serves as a valuable resource for functional genomic studies and identification of virulence-associated secreted effectors in C. heterostrophus.