Mesbah L A, Kneppers T J, Takken F L, Laurent P, Hille J, Nijkamp H J
Department of Genetics, Institute for Molecular Biological Sciences, BioCentrum Amsterdam, The Netherlands.
Mol Gen Genet. 1999 Feb;261(1):50-7. doi: 10.1007/s004380050940.
The Alternaria stem canker disease of tomato is caused by the necrotrophic fungal pathogen Alternaria alternata f. sp. lycopersici (AAL). The fungus produces AAL toxins that kill the plant tissue. Resistance to the fungus segregates as a single locus, called Asc, and has been genetically mapped on chromosome 3 of tomato. We describe here the establishment of a 1383-kb YAC contig covering the Asc locus and a series of plants selected for recombination events around the Asc locus. It was shown that the YAC contig corresponds to a genetic distance of at least 11.2 cM. Thus, the recombination rate in the Asc region is six times higher (123 kb/cM) than the average for the tomato genome. Furthermore, the Asc locus could be localised to a 91-kb fragment, thus paving the way for the cloning and identification of the Asc gene(s) by complementation.
番茄链格孢茎溃疡病由坏死营养型真菌病原体链格孢菌番茄专化型（AAL）引起。该真菌产生的AAL毒素会杀死植物组织。对该真菌的抗性作为一个单一位点进行分离，称为Asc，并且已在番茄的3号染色体上进行了遗传定位。我们在此描述了一个覆盖Asc位点的1383 kb酵母人工染色体（YAC）重叠群的构建，以及一系列围绕Asc位点选择用于重组事件的植株。结果表明，该YAC重叠群对应的遗传距离至少为11.2厘摩（cM）。因此，Asc区域的重组率（123 kb/cM）比番茄基因组的平均重组率高六倍。此外，Asc位点可定位到一个91 kb的片段上，从而为通过互补作用克隆和鉴定Asc基因铺平了道路。
