| Avena nuda L.(Naked oat)belongs to Avena L.,Gramineae family,which is an important kind of grain,forage and feed crops.The germplasm of this species is stored as seeds.Inevitable changes of seeds from the formation to maturity occur to aging in conservation process because of the comperhensive function under the seed itself and outside environmental factor.Naked oat No.9Dingyan and No.1Yanke of Avena nuda L.were selected as materials were used to study and evaluate effect of the appropriate sample size,seeds aging and regeneration population size on the alteration of genetic integrity by SSR molecular marker technique.The purpose of this study was to provide basic data for making a criteria for preserving and regenerating naked oat germplasm resources and the updating of standards.The main results were shown as follows:1.Nine groups of different sample size of naked oat(10,20,30,40,50,60,70,80,90 individuals per group)were set randomly and thenumber of alleles,the effective number of alleles,Shannon index and other genetic parameters among different sample sizes were studied.The results showed that 20 polymorphic primers were screened from 134 SSR primers,and 43 and 32 alleles were detected in No.9Dingyan and No.1Yanke,respectively.And number of alleles per locus was 2.09 and 1.60,respectively.The sample size was related to the number of alleles and the percentage of polymorphic loci(No.9Dingyan were 0.002** and 0.003** respectively,No.1Yanke were 0.015* and 0.012* respectively).In No.9Dingyan and No.1Yanke materials,the S curve(the number of alleles and the percentage of polymorphic loci)increased slowly and reached a plateau when the sample sizes were more than 70 and 50.The standard deviations of other genetic parameters were de-creased with the sample size more than 70 and 50.Therefore,the suitable sample sizes of the No.9Dingyan and No.1Yanke were chosen as 70 and 50 respectively.2.Two kinds of naked oat materials were treated by artificial aging to get different germination rate groups,and genetic integrity analysis was carried out by SSR molecular marker technique.The number of alleles,the number of effective alleles,the diversity index and the Shannon index were significantly lower than that of in the control group D9-0(germination rate >90%)when the germination rate was lower than that of in the control group D9-1(germination rate 80%-85%),and there were no significant difference between group D9-1(germination rate 80-85%),D9-2(germination rate 60-70%)and D9-3(germination rate <30%).Considering the genetic diversity parameters and UPGMA cluster analysis entirely,it was suggested that when the germination rate of No.9Dingyan was reduced to less than 85%,it was necessary to reproduce.There were no significant differences in the parameters of four different germination rate of No.1Yanke,but all of them decreased along with the decrease of germination rate.3.The effects of the sample size of different regeneration population on the genetic integrity of No.1Yanke were studied.The number of alleles,the number of effective alleles,the genetic diversity index and the Shannon index of the three regeneration populations(50,100,150)were significantly different compared to the control group,and the difference among the three regeneration populations were not significant The number of alleles,the number of polymorphic loci and the percentage of polymorphic loci were lower than that of in the control group,Therefore,the effect of regeneration population on the genetic integrity of germplasm was not significant.4.There were significant positive correlation between the number of alleles,the number of effective alleles,the genetic diversity index andthe Shannon index in the sample size(50,90)and the regeneration population(50,100)(0.003**,0.002**,respectively).And the Pearson correlation coefficient of the sample size(90)and the population(100)was greater than that of the sample size(50)and the regeneration population(50)reached 0.998.It is shown that the sample size(90)and the regeneration population(100)are more representative of the genetic integrity to the population in the production practice. |
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