苎麻自交纯合进度研究

【目的】研究苎麻自交后代群体的遗传多样性和群体结构，探究自交纯合进度，对自交后代群体的纯合趋势进行判断。【方法】以中苎1号为材料，采用筛选出的多态性高的31对SSR引物和48对SRAP引物对3个自交后代群体的基因组DNA进行扩增。通过DNA位点纯合率和遗传多样性参数分析群体的遗传多样性。用Structure、NTSYS和AMOVA软件对群体结构进行分析。并用标记指数来比较SSR和SRAP标记方法的标记效率。【结果】SSR和SRAP标记得到的多样性指标变化明显，从S₃代到S₅代，平均扩增出57条和157条多态性条带，DNA位点纯合率上升了5.2%和4.61%，多态性位点减少了13个和44个，有效等位基因数降低了0.7883个和2.1629个，基因多样性下降了0.1143和0.0684，多样性指数降低了0.0465和0.1207。用Structure软件对群体结构分析表明S₅代群体中蓝色组分最多，均在65%以上。主成分分析表明，S₃群体的分散程度最高，S₄和S₅群体比较集中，而且S₃群体包含了S₄和S₅群体的大部分。2种标记方法得到的群体结构和主成分分析表明，经过连续自交，后代群体的一致性越来越好。用AMOVA软件对群体内和群体间的分子变异情况分析表明2种标记方法都显示群体内变异（94.69%和99.02%）明显大于群体间变异（5.31%和0.98%），均达到整体变异的94%以上。SSR标记得到的位点平均信息量（H_av=0.4689）高于SRAP的估计值（H_av=0.4197），而平均有效复合指数（EMR=3.2781）SRAP标记大于SSR标记（EMR=1.8562），标记效率值SRAP标记（MI=1.3758）大于SSR标记（MI=0.8704）。【结论】SSR和SRAP两种分子标记适于苎麻资源的遗传多样性和群体结构分析。随着自交代数的增多，后代群体的一致性不断提高，杂合度逐渐降低。

Study on Homozygous Progress Evaluation of Self-Pollination in Ramie (Boehmeria Nivea L.)

【Objective】The objective of this study was to demonstrate genetic diversity, population structure and the rate of purification of inbred progenies in ramie, and to further identify the homozygous trends. 【Method】A total of 31 pairs of SSR and 48 pairs of SRAP primers were screened out based on inbred progenies of Zhong Zhu No.1. Genetic diversity was analyzed by the homozygous locus ratio and genetic diversity parameters, population structure of inbred progenies were analyzed by using Structure, NTSYS- pcV2.1 and AMOVA softwares. Marker index(MI) was calculated to assess the discriminatory power of SSR and SRAP.【Result】 SSR and SRAP markers indicated that all genetic diversity parameters decreased obviously from S₃ to S₅, 57 and 157 polymorphic bands were amplified, the homozygous locus ratio increased by 5.2% and 4.61%, the average polymorphic loci dropped by 13 and 44, the average effective number of alleles dropped by 0.7883 and 2.1629, Nei’s gene diversity dropped by 0.1143 and 0.0684, and the average Shannon’s information index dropped by 0.0465 and 0.1207. The number of blue bands was over 65% in S₅ generation groups by SSR and SRAP with Structure software. The dispersion of S₃ generation group was higher than S₄ and S₅ generation groups, S₃ generation groups mainly contain S₄ and S₅ generation groups. Population structure and PCA by SSR and SRAP showed the uniformity of inbred progenies increased gradually. Genetic variation among populations by SSR and SRAP was larger than the variation within populations with AMOVA software, and the total variation was more than 94%. The average heterozygosity obtained using SSR (H_av=0.4689) was higher than estimated using SRAP (H_av=0.4197). Mean effective multiplex ratio was maximum for the SRAP (EMR=3.2781) followed by SSR(EMR=1.8562). Consequently, the marker index, which is the mean of the product of H_av and EMR was maximum for SRAP followed by SSR.【Conclusion】SSR and SRAP are suitable for genetic diversity and populations structure of ramie germplasm, with the increase of the number of inbred generations, the uniformity of inbred progenies increased gradually, and the average heterozygosity(H) reduced gradually.