Whole-chromosome paints in maize reveal rearrangements, nuclear domains, and chromosomal relationships

Significance Whole-chromosome oligo-FISH paints using synthetic oligonucleotide libraries that can be amplified and labeled were generated for all 10 chromosomes of maize, facilitating chromosome studies with high sensitivity and specificity for genetically diverse lines. Applications include visualization of simple or complex chromosomal aberrations, establishment of chromosomal domains, illustration of mitotic and meiotic behavior, and providing insights into chromosomal relationships.
Whole-chromosome painting probes were developed for each of the 10 chromosomes of maize by producing amplifiable libraries of unique sequences of oligonucleotides that can generate labeled probes through transcription reactions. These paints allow identification of individual homologous chromosomes for many applications as demonstrated in somatic root tip metaphase cells, in the pachytene stage of meiosis, and in interphase nuclei. Several chromosomal aberrations were examined as proof of concept for study of various rearrangements using probes that cover the entire chromosome and that label diverse varieties. The relationship of the supernumerary B chromosome and the normal chromosomes was examined with the finding that there is no detectable homology between any of the normal A chromosomes and the B chromosome. Combined with other chromosome-labeling techniques, a complete set of whole-chromosome oligonucleotide paints lays the foundation for future studies of the structure, organization, and evolution of genomes.