Citrus as a molecular contact point for co-evolution of Alternaria pathogens

•Alternaria black rot, Alternaria leaf spot of rough lemon, and Alternaria brown spot of tangerines are three major citrus Alternaria pathogens.•Citrus could be considered as a molecular contact point for host-selective toxin (HST)-mediated co-evolution of these Alternaria pathogens and susceptibility in the field.•ACR-toxin is an HST produced by the rough lemon pathotype, and the target site of the toxin was identified as rough lemon mitochondria.•The biosynthetic gene cluster for ACR-toxin production was identified on the 1.5 Mb-chromosome of the rough lemon pathotype.•Another gene cluster for ACT-toxin production is located on the 1.9 Mb-chromosome of the tangerine pathotype.•These TOX genes were shown to have a role in ACR- or ACT-toxin biosynthesis by using gene disruption and silencing.

Alternaria black rot, Alternaria leaf spot of rough lemon, and Alternaria brown spot of tangerines are three major citrus Alternaria pathogens. Citrus could be considered as a molecular contact point for host-selective toxin (HST)-mediated co-evolution of these Alternaria pathogens and susceptibility in the field. ACR-toxin is an HST produced by the rough lemon pathotype, and the target site of the toxin was identified as rough lemon mitochondria. The biosynthetic gene cluster for ACR-toxin production is on the 1.5 Mb-chromosome of the rough lemon pathotype. Another gene cluster for ACT-toxin production is located on the 1.9 Mb-chromosome of the tangerine pathotype. These TOX genes shown to have a role in ACR- or ACT-toxin biosynthesis by using gene disruption and silencing.