Production of viable male unreduced gametes in Brassica interspecific hybrids is genotype specific and stimulated by cold temperatures

Mason, Annaliese S., Nelson, Matthew N., Yan, Guijin and Cowling, Wallace A. (2011) Production of viable male unreduced gametes in Brassica interspecific hybrids is genotype specific and stimulated by cold temperatures. BMC Plant Biology, 11 103.1-103.13. doi:10.1186/1471-2229-11-103


Author Mason, Annaliese S.
Nelson, Matthew N.
Yan, Guijin
Cowling, Wallace A.
Title Production of viable male unreduced gametes in Brassica interspecific hybrids is genotype specific and stimulated by cold temperatures
Journal name BMC Plant Biology   Check publisher's open access policy
ISSN 1471-2229
Publication date 2011-06-11
Sub-type Article (original research)
DOI 10.1186/1471-2229-11-103
Open Access Status DOI
Volume 11
Start page 103.1
End page 103.13
Total pages 13
Place of publication London, United Kingdom
Publisher BioMed Central
Collection year 2012
Language eng
Formatted abstract
Background: Unreduced gametes (gametes with the somatic chromosome number) may provide a pathway for evolutionary speciation via allopolyploid formation. We evaluated the effect of genotype and temperature on male unreduced gamete formation in Brassica allotetraploids and their interspecific hybrids. The frequency of unreduced gametes post-meiosis was estimated in sporads from the frequency of dyads or giant tetrads, and in pollen from the frequency of viable giant pollen compared with viable normal pollen. Giant tetrads were twice the volume of normal tetrads, and presumably resulted from pre-meiotic doubling of chromosome number. Giant pollen was defined as pollen with more than 1.5 × normal diameter, under the assumption that the doubling of DNA content in unreduced gametes would approximately double the pollen cell volume. The effect of genotype was assessed in five B. napus, two B. carinata and one B. juncea parents and in 13 interspecific hybrid combinations. The effect of temperature was assessed in a subset of genotypes in hot (day/night 30°C/20°C), warm (25°C/15°C), cool (18°C/13°C) and cold (10°C/5°C) treatments.

Results:
Based on estimates at the sporad stage, some interspecific hybrid genotypes produced unreduced gametes (range 0.06 to 3.29%) at more than an order of magnitude higher frequency than in the parents (range 0.00% to 0.11%). In nine hybrids that produced viable mature pollen, the frequency of viable giant pollen (range 0.2% to 33.5%) was much greater than in the parents (range 0.0% to 0.4%). Giant pollen, most likely formed from unreduced gametes, was more viable than normal pollen in hybrids. Two B. napus × B. carinata hybrids produced 9% and 23% unreduced gametes based on post-meiotic sporad observations in the cold temperature treatment, which was more than two orders of magnitude higher than in the parents.

Conclusions:
These results demonstrate that sources of unreduced gametes, required for the triploid bridge hypothesis of allopolyploid evolution, are readily available in some Brassica interspecific hybrid genotypes, especially at cold temperatures.
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status Non-UQ
Additional Notes Article Number 103, pp. 1-13

Document type: Journal Article
Sub-type: Article (original research)
Collections: Non HERDC
School of Agriculture and Food Sciences
 
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Created: Thu, 15 Mar 2012, 11:32:30 EST by Annaliese Mason on behalf of School of Agriculture and Food Sciences