Abstract
The B chromosomes of maize typically undergo nondisjunction during the second microspore division (generative cell division). When the microspore nucleus contains only one B chromosome, two kinds of sperm result, one with two B chromosomes and one with no B chromosomes. The sperm with the B chromosomes preferentially fertilizes the egg cell. Previous studies of these phenomena have been limited to genetic analysis and chromosome spreads. In this study we show that a B chromosome-specific probe can be used with fluorescence in situ hybridization (FISH) analysis to detect the presence, location, and frequency of B chromosomes in intact interphase nuclei within mature pollen of maize. Using genetic line TB-10L18, our results indicate that nondisjunction of the B centromere occurs at an average frequency of 56.6%, based on four plants and 1306 pollen grains analyzed. This is consistent with the results of genetic studies using the same B-A translocation. In addition, our results suggest that B chromosome nondisjunction can occur during the first microspore division. Spatial distribution of the B chromosome-specific probe appears to be largely confined to one tip of the sperm nucleus, and a DNA fragment found outside the pollen nuclei often hybridizes to the B chromosome-specific probe.
Full Text
The Full Text of this article is available as a PDF (2.5 MB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Carlson W. R. Factors affecting preferential fertilization in maize. Genetics. 1969 Jul;62(3):543–554. doi: 10.1093/genetics/62.3.543. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Carlson W. R., Roseman R. R. A new property of the maize B chromosome. Genetics. 1992 May;131(1):211–223. doi: 10.1093/genetics/131.1.211. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Randolph L F. Genetic Characteristics of the B Chromosomes in Maize. Genetics. 1941 Nov;26(6):608–631. doi: 10.1093/genetics/26.6.608. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Roman H. Mitotic Nondisjunction in the Case of Interchanges Involving the B-Type Chromosome in Maize. Genetics. 1947 Jul;32(4):391–409. doi: 10.1093/genetics/32.4.391. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Shi L., Zhu T., Mogensen H. L., Keim P. Sperm Identification in Maize by Fluorescence in Situ Hybridization. Plant Cell. 1996 May;8(5):815–821. doi: 10.1105/tpc.8.5.815. [DOI] [PMC free article] [PubMed] [Google Scholar]