A new property of the maize B chromosome

• Published in: Genetics (Austin) Vol. 131; no. 1; pp. 211 - 223
• Main Authors: Carlson, W.R. (University of Iowa, Iowa City, IA), Roseman, R.R
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Genetics Soc America 01.05.1992; Genetics Society of America
• Subjects: Anaphase; Biological and medical sciences; CHROMOSOME; chromosome elimination; chromosome translocation; chromosome transmission; Chromosomes; Chromosomes - ultrastructure; Corn; CROMOSOMAS; Crossing Over, Genetic; Cytogenetics; cytology; Fundamental and applied biological sciences. Psychology; Genetics; Genetics of eukaryotes. Biological and molecular evolution; Investigations; Medical research; MEIOSE; MEIOSIS; Metaphase; Mitosis; Pteridophyta, spermatophyta; Translocation; TRANSLOCATION CHROMOSOMIQUE; Translocation, Genetic; TRASLOCACION DE CROMOSOMAS; ultrastructure; Vegetals and fungi; ZEA MAYS; Zea mays - cytology; Zea mays - genetics; Chromosomal aberration; Monocotyledones; Chromatin; Zea mays; Segregation; Accessory B chromosome; Meiosis; Chromosome elimination; Disjunction; Gramineae; Angiospermae; Cytogenetics; Deletion; Abnormal chromosome; Spermatophyta; Chromosome translocation
• ISSN: 0016-6731; 1943-2631; 1943-2631
• DOI: 10.1093/genetics/131.1.211

TB-9Sb is a translocation between the B chromosome and chromosome 9 in maize. Certain deletions of B chromatin from the translocation cause a sharp decrease in B-9 transmission compared to the rate for standard TB-9Sb. The deletions remove components of a B chromosome genetic system that serves to suppress meiotic loss in the female. At least two distinct B-chromosome regions suppress meiotic loss: one on the B-9 and one on 9-B. The system operates by stabilizing univalent B-type chromosomes. It allows the univalents to migrate to one pole in meiosis, despite the absence of a pairing partner. The findings reported here are the first evidence for genetic control of meiotic loss by a B chromosome. However, it is proposed that the practice of suppressing meiotic loss is common to the B chromosomes of all species. The need to suppress meiotic loss results from the fact that B chromosomes are frequently unpaired in meiosis and subject to very high frequencies of loss. B chromosomes may utilize one or more of the following methods to suppress meiotic loss: (a) regular migration of univalent B's to one pole in meiosis, (b) enhanced recombination between B chromosomes and (c) mitotic nondisjunction