摘要
An original base population with wide genetic variability was developed by multiple-parent cross- ing,intermating and recrossing using the dominant male-sterile gene ms2(Tal).Then the phenotypic recurrent selection was conducted for the male-sterile plants in order to improve the population and develop a gene pool with increased resistance to scab in wheat.Generations RC_0-RC_2 and RC_1-RC_5 from the resistance resource pool were evaluated for the resistance and the effect of population improvement was analyzed in Nanjing under soil-surface inoculation with F.graminearum-diseased seeds in 1988/1989 and single-floret inoculation with ascospore suspension of G.zeae in 1991/1992,respectively.The experimental results of the soil-surface inoculation indicated that the numbers or percentages of diseased spikelets and seeds per spike of the male-fertile plants were decreased significantly and the comprehensive resistance of the population to scab was obviously increased.The percentages of uninfected seeds per spike in generations RC_0,RC_1 and RC_2 were 49.2%,65.5% and 70.7%,respectively.The frequencies of plants with lower than 30% of diseased spikelet and seed percentages in the population were increased by 40% and 36%,respectively,through 2 cycles of se- lection.Under the condition of the single-floret inoculation,the results further demonstrated that the resistance to the fungal spread could be improved significantly through the phenotypic recurrent selection.The opportunity of obtaining superior resistant plants from the population would be enhanced gradually with the development of the gene pool.On average,from RC_1 to RC_5,the population mean of diseased spikelets of inoculated spikes was reduced by 8.6% and the frequency of resistant plants with fewer than 4 diseased spikelets per inoculated spike was increased by 4.2%,respectively,per cycle.The frequency of susceptible plants with more than 10 diseased spikelets in inoculated spikes was decreased by 9.2% after 4 cycles of se- lection.The genetic variance for resistance reduced remarkably but no significant decrease in the genetic coefficient of variation was found during the first 4 cycles of selection.
An original base population with wide genetic variability was developed by multiple-parent cross-ing,intermating and recrossing using the dominant male-sterile gene ms2（Tal）.Then the phenotypic recurrentselection was conducted for the male-sterile plants in order to improve the population and develop a gene poolwith increased resistance to scab in wheat.Generations RC<sub>0</sub>-RC<sub>2</sub> and RC<sub>1</sub>-RC<sub>5</sub> from the resistance resource poolwere evaluated for the resistance and the effect of population improvement was analyzed in Nanjing undersoil-surface inoculation with F.graminearum-diseased seeds in 1988/1989 and single-floret inoculation withascospore suspension of G.zeae in 1991/1992,respectively.The experimental results of the soil-surfaceinoculation indicated that the numbers or percentages of diseased spikelets and seeds per spike of themale-fertile plants were decreased significantly and the comprehensive resistance of the population to scab wasobviously increased.The percentages of uninfected seeds per spike in generations RC<sub>0</sub>,RC<sub>1</sub> and RC<sub>2</sub> were49.2%,65.5% and 70.7%,respectively.The frequencies of plants with lower than 30% of diseased spikeletand seed percentages in the population were increased by 40% and 36%,respectively,through 2 cycles of se-lection.Under the condition of the single-floret inoculation,the results further demonstrated that the resistanceto the fungal spread could be improved significantly through the phenotypic recurrent selection.Theopportunity of obtaining superior resistant plants from the population would be enhanced gradually with thedevelopment of the gene pool.On average,from RC<sub>1</sub> to RC<sub>5</sub>,the population mean of diseased spikelets ofinoculated spikes was reduced by 8.6% and the frequency of resistant plants with fewer than 4 diseasedspikelets per inoculated spike was increased by 4.2%,respectively,per cycle.The frequency of susceptibleplants with more than 10 diseased spikelets in inoculated spikes was decreased by 9.2% after 4 cycles of se-lection.The genetic variance for resistance reduced remarkably but no significant decrease in the geneticcoefficient of variation was found during the first 4 cycles of selection.
基金
the National Natural Science Foundation of Cina
National 8th Five-Year Plan for Tackling Key Problems of Science and Technology in Ctina
