AK-toxin I is a host-specific phytotoxic metabolite. AK-toxin I causes black spot disease of pear trees[1].
References
[1] Tadakazu Nakashima, et al. Isolation and Structures of AK-Toxin I and II, Host-specific Phytotoxic Metabolites Produced by Alternaria alternata Japanese Pear Pathotype. Agricultural and Biological Chemistry, Volume 49, Issue 3, 1 March 1985, Pages 807-815.