tailieunhanh - báo cáo khoa học: " Production of viable male unreduced gametes in Brassica interspecific hybrids is genotype specific and stimulated by cold temperatures"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Production of viable male unreduced gametes in Brassica interspecific hybrids is genotype specific and stimulated by cold temperatures | Mason et al. BMC Plant Biology 2011 11 103 http 1471 -2229 11 103 BMC Plant Biology RESEARCH ARTICLE Open Access Production of viable male unreduced gametes in Brassica interspecific hybrids is genotype specific and stimulated by cold temperatures Annaliese S Mason Matthew N Nelson Guijun Yan and Wallace A Cowling 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 X 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 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 to at more than an order of magnitude higher frequency than in the parents range to . In nine hybrids that produced viable mature pollen the frequency of viable giant pollen range to was much greater than in the parents range to . Giant pollen most likely formed from unreduced gametes was more viable than normal pollen in hybrids. Two B. napus X B. carinata hybrids produced