Overexpression of the tomato Asc-1 gene mediates high insensitivity to AAL toxins and fumonisin B1 in tomato hairy roots and confers resistance to Alternaria alternata f. sp. lycopersici in Nicotiana umbratica plants.
The sphinganine-analog mycotoxins (SAMs) fumonisin B1 and AAL toxins are inhibitors of eukaryotic sphinganine N-acyltransferase in vitro. Treatment of eukaryotes with SAMs generally results in an accumulation of sphingoid base precursors and a depletion of complex sphingolipids. The asc,asc genotypes of tomato (Lycopersicon esculentum) and Nicotiana umbratica are sensitive to SAMs and host of the AAL toxin-producing fungus Alternaria alternata f. sp. lycopersici. Codominant insensitivity to SAMs in tomato is mediated by the Asc-1 gene, and sensitivity is associated with a frame-shift mutation present in asc-1. We investigated the function of Asc-1 in mediating insensitivity to SAMs and resistance to the fungus by overexpression of asc-1 and Asc-1. In this study, it is shown that overexpression of these genes did not lead to visual symptoms in tomato hairy roots and N. umbratica plants. Overexpression of asc-1 did not influence the (in)sensitivity to SAMs. Overexpression of Asc-1 in SAM-sensitive hairy roots and N. umbratica plants, however, mediated a high insensitivity to SAMs and resistance to plant infection by Alternaria alternata f. sp. lycopersici.
Brandwagt
Bas F
BF
Department of Genetics, Free University, BioCentrum Amsterdam, The Netherlands.
Kneppers
Tarcies J A
TJ
Nijkamp
H John J
HJ
Hille
Jacques
J
D000528:Alternaria / Q000472:pathogenicity*; D027182:Amino Acid Transport System y+ / Q000235:genetics*; D002264:Carboxylic Acids / Q000494:pharmacology*; D037341:Fumonisins; D018506:Gene Expression Regulation, Plant; D007113:Immunity, Innate / Q000235:genetics; D018551:Solanum lycopersicum / Q000187:drug effects / Q000235:genetics* / Q000382:microbiology; D018517:Plant Roots / Q000187:drug effects*; D014026:Nicotiana / Q000235:genetics* / Q000382:microbiology
D027182:Amino Acid Transport System y+; D002264:Carboxylic Acids; D037341:Fumonisins; C056933:fumonisin B1