利用SRAP标记研究繁殖群体量对芝麻种质资源遗传完整性的影响

Effects of Regeneration Population on the Genetic Integrity of Sesame Germplasm Using SRAP Markers

研究繁殖群体量对芝麻种质资源遗传完整性的影响,以确定适宜的繁殖群体量,为种质资源更新繁殖提供理论参考。利用SRAP分子标记技术对育成品种和地方种质2种不同类型的芝麻种质资源的不同群体量的遗传参数进行分析。结果显示:(1)育成品种:随机抽取了10、15、20、25、30、35和40株的7个群体量梯度,24对引物共扩增到DNA位点525个,平均每对引物扩增21.88个,多态性位点24个,占总位点数的4.57%。随着群体量的不断增加,扩增总位点数和遗传相似系数均表现为不断增加,多态性位点比率和遗传距离均呈现先升后降趋势。当群体量达到35~40株时,遗传相似系数达到一定高值(0.998 73和1.000 00),遗传距离降低到一定程度(0.000 64和0.000 00)。聚类结果显示群体量为35和40株的群体被紧密聚在一起,因此可认为育成品种的繁殖群体量达到35~40株时可以保持其遗传完整性;(2)地方种质:随机抽取10、15、20、25、30、35、40、45、50、55和60株的11个群体量梯度,24对引物共扩增到DNA位点552个,平均每对引物扩增23.00个,多态性位点44个,占总位点数的7.97%。随着群体量的不断增加,扩增总位点数波动上升,多态性位点比率和遗传距离呈先升后降然后再轻度变化的趋势。遗传相似系数则随群体量的增大表现为先下降后上升然后轻度下降后再次回升的趋势,并于群体量为40和60株时达到最大值0.99758。聚类结果显示群体量为50、55和60株的群体被紧密聚在一起,因此可认为地方种质的繁殖群体量达到50~55株时可保持其遗传完整性;(3)在芝麻种质资源繁育中,不同类型的种质资源由于其遗传背景的纯度存在差异,应选择不同的繁殖群体量以保持其遗传完整性。

The effect of regeneration population on the genetic integrity of sesame germplasm was studied to determine the appropriate population size and provide theoretical references for germplasm renewal and reproduction.The genetic parameters of two different types of sesame germplasm including released cultivar and local germplasm were analyzed using SRAP markers.(1) Released cultivar: Seven gradients of population size including 10, 15, 20, 25, 30, 35 and 40 were selected randomly. 24 pairs of primers were co-amplified to 525 loci, with an average of 21.88 loci per primer pairs, including 24 polymorphic loci, accounting for 4.57% of the total locus. With the increase of population size, the total amplification loci and genetic similarity coefficient increased, and the ratio of polymorphic loci and genetic distance increased and then decreased. When the population size reached 35-40 plants, the genetic similarity coefficient reached a certain high value(0.998 73 and 1.000 00), and the genetic distance decreased to a certain degree(0.000 64 and 0.000 00). The clustering results showed that the populations with 35 and 40 were closely clustered. So the genetic integrity could be maintained when the population size of released cultivar reached 35-40.(2) Local germplasm: Eleven gradients of population size including 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 and 60 were selected randomly. 24 pairs of primers were co-amplified to 552 DNA locus, with an average of 23.00 locus per primer pairs, and including 44 polymorphic loci, accounting for 7.97% of the total loci. With the increase of population size, the total amplification loci fluctuation increased, and the ratio of polymorphic loci and genetic distance first increased, then decreased and then slightly changed. With the increase of population size, the genetic similarity coefficient first decreased, then increased, then slightly decreased and then rose again, and reached the maximum value of 0.99758 when the population size was 40 and 60 plants. The clustering results showed that the populations of 50, 55 and 60 plants were closely clustered. So it could be considered that the genetic integrity of local germplasm could be maintained when the reproductive population reached 50-55 plants.(3) In the regenerating of sesame germplasm, different germplasm types should have different population size to maintain the genetic integrity because of the different genetic purity.