Transcriptome Analysis of the Cf-13-Mediated Hypersensitive Response of Tomato to Cladosporium fulvum Infection

Tomato leaf mold disease caused by Cladosporium fulvum (C. fulvum) is one of the most common diseases affecting greenhouse tomato production. Cf proteins can recognize corresponding AVR proteins produced by C. fulvum, and Cf genes are associated with leaf mold resistance. Given that there are many physiological races of C. fulvum and that these races rapidly mutate, resistance to common Cf genes (such as Cf-2, Cf-4, Cf-5, and Cf-9) has decreased. In the field, Ont7813 plants (carrying the Cf-13 gene) show effective resistance to C. fulvum; thus, these plants could be used as new, disease-resistant materials. To explore the mechanism of the Cf-13-mediated resistance response, transcriptome sequencing was performed on three replicates each of Ont7813 (Cf-13) and Moneymaker (MM; carrying the Cf-0 gene) at 0, 9, and 15 days after inoculation (dai) for a total of 18 samples. In total, 943 genes were differentially expressed, specifically in the Ont7813 response process as compared to the Moneymaker response process. Gene ontology (GO) classification of these 943 differentially expressed genes (DEGs) showed that GO terms, including hydrogen peroxide metabolic process (GO_Process), secondary active transmembrane transporter activity (GO_Function), and mismatch repair complex (GO_Component), which were the same as 11 other GO terms, were significantly enriched. An analysis of the Kyoto Encyclopedia of Genes and Genomes (KEGG) revealed that many key regulatory genes of the Cf-13-mediated resistance response processes were involved in the plant hormone signal transduction pathway, the plant-pathogen interaction pathway, and the MAPK signaling pathway-plant pathway. Moreover, during C. fulvum infection, jasmonic acid (JA) and salicylic acid (SA) contents significantly increased in Ont7813 at the early stage. These results lay a vital foundation for further understanding the molecular mechanism of the Cf-13 gene in response to C. fulvum infection.

Automated summary

Tomato leaf mold disease caused by Cladosporium fulvum is a common disease in greenhouse tomato production. The Cf genes play a role in resistance to the disease, but the effectiveness of common Cf genes has decreased due to the rapid mutation of C. fulvum. Ont7813 plants carrying the Cf-13 gene show effective resistance. Transcriptome sequencing revealed differentially expressed genes and enriched gene ontology terms in the response process. Key regulatory genes involved in plant hormone signal transduction, plant-pathogen interaction, and MAPK signaling pathways were identified. The JA and SA contents increased significantly in Ont7813 during C. fulvum infection.