A new single‐locus cytogenetic mapping system for maize (Zea mays L.): overcoming FISH detection limits with marker‐selected sorghum (S. propinquum L.) BAC clones

• Published in: The Plant journal : for cell and molecular biology Vol. 35; no. 5; pp. 647 - 659
• Main Authors: Koumbaris, George L., Bass, Hank W.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.09.2003; Blackwell Science
• Subjects: Avena - genetics; Biological and medical sciences; Chromosome Mapping - methods; Chromosomes, Artificial, Bacterial - genetics; Chromosomes, Plant - genetics; cytogenetic; Diverse techniques; FISH; Fundamental and applied biological sciences. Psychology; Genetic Markers - genetics; Genome, Plant; genomics; In Situ Hybridization, Fluorescence - methods; maize; Molecular and cellular biology; pachytene; Poaceae - genetics; sorghum; Sorghum - genetics; Zea mays - genetics; Genetic mapping; Monocotyledones; sorghum; Zea mays; pachytene; cytogenetic; maize; Gene; Gramineae; Angiospermae; Fluorescence in situ hybridization; Cytogenetics; FISH; genomics; Spermatophyta
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1046/j.1365-313X.2003.01829.x

Summary The development of a cytogenetic map for maize (Zea mays L.) is shown to be feasible by means of a combination of resources from sorghum and oat that overcome limitations of single‐copy gene detection. A maize chromosome‐addition line of oat, OMAd9.2, provided clear images of optically isolated pachytene chromosomes through a chromosome spread and painting technique. A direct labeled oligonucleotide fluorescence in situ hybridization (FISH) probe MCCY specifically stained the centromere. The arm ratio (long/short) for maize chromosome 9 in the addition line was 1.7, comparable to the range of 1.6–2.1 previously reported for maize chromosome 9. A sorghum (Sorghum propinquum L.) BAC library was screened by hybridization with each of three maize core‐bin‐marker (CBM) probes: umc109 (CBM9.01), umc192/bz1 (CBM9.02), and csu54b (CBM9.08). A single BAC clone for each marker was chosen; designated sCBM9.1, sCBM9.2, or sCBM9.8; and used as a FISH probe on pachytene spreads from OMAd9.2. In each case, discrete FISH signals were observed, and their cytogenetic positions were determined to be 9S.79 (at position 79% of the length of chromosome 9 short arm) for sCBM9.1, 9S.65 for sCBM9.2, and approximately 9L.95 for sCBM9.8. These map positions were co‐linear with linkage‐map positions for these and other loci common to the linkage and cytogenetic maps. This work represents a major breakthrough for cytogenetic mapping of the maize genome, and also provides a general strategy that can be applied to cytogenetic mapping of other plant species with relatively large and complex genomes.