%0 Journal Article
%T Production of viable male unreduced gametes in Brassica interspecific hybrids is genotype specific and stimulated by cold temperatures
%A Annaliese S Mason
%A Matthew N Nelson
%A Guijun Yan
%A Wallace A Cowling
%J BMC Plant Biology
%D 2011
%I BioMed Central
%R 10.1186/1471-2229-11-103
%X 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 กม 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.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.Unreduced gametes, or gametes with the somatic chromosome number (also referred to as "2n" gametes), are thought to play an important role in the evolution of polyploid species [1,2]. If two unreduced gametes unite, a fertile polyploid hybrid may form-either autopolyploid (fertilization within species) or allopolyploid (fertilization between species). Most plant species are now thought to be of recent or ancestral polyploid origin [3]. However, little is known about the frequency of unreduced gamete formation and the genetic and environmental factors which affect unreduced gamete production in most genera [2]. In Solanum tuberosum and Trifolium pratense, unreduced gamete production appears to be initiated by a monogenic recessive allele with other genes affecting the frequency of production (reviewed by Bretagnolle and Thompson (1995) [4]). Unreduced gamete-producing mutants linked to defects in the meiotic cell cycle machinery have also been recently identified in model plant Arabidopsis thaliana, leading to greater understanding o
%U http://www.biomedcentral.com/1471-2229/11/103