Tomato susceptibility/resistance to stem canker disease caused by
Alternaria alternata f. sp.
lycopersici and its pathogenic factor AAL-toxin is determined by the presence of the
Asc1 gene. Several cultivars of commercial tomato (
Solanum lycopersicum var.
lycopersicum,
SLL) are reported to
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Tomato susceptibility/resistance to stem canker disease caused by
Alternaria alternata f. sp.
lycopersici and its pathogenic factor AAL-toxin is determined by the presence of the
Asc1 gene. Several cultivars of commercial tomato (
Solanum lycopersicum var.
lycopersicum,
SLL) are reported to have a mutation in
Asc1, resulting in their susceptibility to AAL-toxin. We evaluated 119 ancestral tomato accessions including
S. pimpinellifolium (
SP),
S. lycopersicum var.
cerasiforme (
SLC) and
S. lycopersicum var.
lycopersicum “jitomate criollo” (
SLJ) for AAL-toxin susceptibility. Three accessions,
SP PER018805,
SLC PER018894, and
SLJ M5-3, were susceptible to AAL-toxin.
SLC PER018894 and
SLJ M5-3 had a two-nucleotide deletion (nt 854_855del) in
Asc1 identical to that found in
SLL cv. Aichi-first. Another mutation (nt 931_932insT) that may confer AAL-toxin susceptibility was identified in
SP PER018805. In the phylogenetic tree based on the 18 COSII sequences, a clade (S3) is composed of
SP, including the AAL-toxin susceptible PER018805, and
SLC. AAL-toxin susceptible
SLC PER018894 and
SLJ M5-3 were in Clade S2 with
SLL cultivars. As
SLC is thought to be the ancestor of
SLL, and
SLJ is an intermediate tomato between
SLC and
SLL,
Asc1s with/without the mutation seem to have been inherited throughout the history of tomato domestication and breeding.
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