B chromosome behavior in maize pollen as determined by a molecular probe.
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.
Rusche
M L
ML
Department of Biological Sciences, Northern Arizona University, Flagstaff 86011, USA.
Mogensen
H L
HL
Shi
L
L
Keim
P
P
Rougier
M
M
Chaboud
A
A
Dumas
C
C
D019921:Biotinylation; D002875:Chromosomes; D015342:DNA Probes; D018744:DNA, Plant; D016650:Fluorescein-5-isothiocyanate; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D011058:Pollen / Q000235:genetics*; D003313:Zea mays / Q000235:genetics*
D015342:DNA Probes; D018744:DNA, Plant; D016650:Fluorescein-5-isothiocyanate