Development and characterization of a genetic linkage map of Cryptococcus neoformans var. neoformans using amplified fragment length polymorphisms and other markers

Forche, A., Xu, J., Vilgalys, R., and Mitchell, T. G. 2000, Development and Characterization of a Genetic Linkage Map of Cryptococcus neoformans var, neoformans Using Amplified Fragment Length Polymorphisms and Other Markers. Fungal Genetics and Biology 31, 189-203, A segregating population of singl e basidiospore isolates from a sexual cross was used to generate the first moderately dense genetic linkage map of Cryptococcus neoformans var. neofor mans (Serotype D), Polymorphic DNA markers were developed using amplified f ragment length polymorphisms, random amplified polymorphic DNA, and gene-en coding sequences, These markers were used to analyze 100 meiotic progeny. A ll markers were tested for distorted segregation with a goodness of fit tes t, Of the total of 181 markers, 148 showed balanced (1:1) segregation ratio s. Segregation distortion was observed for 33 markers, Based on all the mar kers, a linkage map was generated that consists of 14 major linkage groups with 127 markers, several small linkage groups, and 2 linkage groups that c onsist only of highly skewed markers. The genetic distance of the linkage m ap is 1356.3 cM. The estimated total haploid genome size for C, neoformans var. neofovmans was calculated using Hulberts method and yielded a map size of 1917 cM, The number of major linkage groups correlates well with the pr oposed number of 13 chromosomes for C. neoformans var. neoformans. Several genes, including CAP64, CnLAC, and the mating-type locus, were mapped, and their associations were consistent with published data. To date, 6 linkage groups have been assigned to their corresponding chromosomes, This linkage map should provide a framework for the ongoing genome sequencing project an d will be a useful tool for studying the genetics and pathogenicity of this important medical yeast. (C) 2000 Academic Press.