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TY - JOUR AU - Zhong, X.-B. AU - Bodeau, J. AU - Fransz, P. F. AU - Williamson, V. M. AU - van Kammen, A. AU - de Jong, J. H. AU - Zabel, P. PY - 1999 DA - 1999/03/01 TI - FISH to meiotic pachytene chromosomes of tomato locates the root-knot nematode resistance gene Mi-1 and the acid phosphatase gene Aps-1 near the junction of euchromatin and pericentromeric heterochromatin of chromosome arms 6S and 6L, respectively JO - Theoretical and Applied Genetics SP - 365 EP - 370 VL - 98 IS - 3 AB - The root-knot nematode resistance gene Mi-1 in tomato has long been thought to be located in the pericentromeric heterochromatin region of the long arm of chromosome 6 because of its very tight genetic linkage (approx. 1 cM) to the markers Aps-1 (Acid phosphatase 1) and yv (yellow virescent). Using Mi-BAC clones and an Aps-1 YAC clone in fluorescence in situ hybridisation (FISH) to pachytene chromosomes we now provide direct physical evidence showing that Mi-1 is located at the border of the euchromatin and heterochromatin regions in the short arm (6S) and Aps-1 in the pericentromeric heterochromatin of the long arm (6L) close to the euchromatin. Taking into account both the estimated DNA content of hetero- and euchromatin regions and the compactness of the tomato chromosomes at pachytene (2 Mb/μm), our data suggest that Mi-1 and Aps-1 are at least 40 Mb apart, a base pair-to-centiMorgan relationship that is more than 50-fold higher than the average value of 750 kb/cM of the tomato genome. An integrated cytogenetic-molecular map of chromosome 6 is presented that provides a framework for physical mapping. SN - 1432-2242 UR - https://doi.org/10.1007/s001220051081 DO - 10.1007/s001220051081 ID - Zhong1999 ER -