AFLP标记分析生活力影响大豆中黄18种质遗传完整性

Analysis of Viability Affecting on Genetic Integrity in Soybean Germplasm Zhonghuang 18 by AFLP Markers

以中黄18种子为试验材料,采用不同时间(0、112、154和196d)老化处理,获得4个群体G0-1、G0-2、G0-3和G0-4,其发芽率分别为98.0%、95.0%、81.0%和79.0%。将这4个群体进行2次田间繁殖,得到4个繁殖一代群体G1-1、G1-2、G1-3和G1-4及4个繁殖二代群体G2-1、G2-2、G2-3和G2-4。以群体G0-1为对照,选用12对AFLP引物组合分析12个群体的遗传完整性。结果显示,所有处理群体与对照群体G0-1的等位基因频率t检验概率值均为1.00,即无显著差异。群体G2-4与对照群体G0-1的遗传相似系数仍高达0.9333,表明发芽率为79.0%群体的繁殖二代群体与对照群体的遗传相似性仍然较高。显著性t检验结果显示,与对照群体G0-1相比,群体G1-1、G2-1、G1-2和G2-2的每位点有效等位基因数(Ae)、遗传多样性指数(H)和香农指数(I)差异不显著;群体G0-3、G0-4、G1-3、G1-4、G2-3和G2-4的上述遗传多样性参数则显著降低。与对照群体G0-1相比,群体G1-1、G2-1、G1-2和G2-2的稀有等位基因数无显著变化;而群体G0-3、G0-4、G1-3、G1-4、G2-3和G2-4的稀有等位基因数则大幅下降。以上结果表明,与对照群体相比,由发芽率分别为98.0%和95.0%的群体更新的子代群体,其群体遗传多样性和稀有等位基因数无显著变化,而由发芽率分别为81.0%和79.0%的群体更新的子代群体,则显著下降。因此,生活力下降比繁殖世代对大豆种质群体的遗传结构影响更大,建议初始发芽率为98.0%的大豆种质更新发芽率标准不应低于81.0%。

Using low temperature genebank is a main way for conserving crop germplasm resources. However,with the extension of storage time,the viability of seeds stored in the genebank will inevitably decline. Therefore,preserved seeds need to be regenerated periodically. In this study,soybean cultivar Zhonghuang 18 was used as a material and aged for different days （0,112,154,and 196 d） to obtain four populations G0-1,G0-2,G0-3,and G0-4. The germination percentages of the four populations were 98.0%,95.0%,81.0%,and 79.0%,respectively. These populations were regenerated twice in the field. The first descendant popu-lations were marked as G1-1,G1-2,G1-3,and G1-4,and the second were marked as G2-1,G2-2,G2-3,and G2-4,respectively. Population G0-1 was taken as the control. The genetic variation between the control and treated populations was detected using AFLP marker. Sixty individual seedlings derived from each population were detected by 12 AFLP primer combinations. The result showed that t-test probability values for allele frequencies were 1.00 between the control and treated populations,which indicated that there was no significant difference in the allele frequencies of the treated population compared with the control. The genetic similarity coefficient between population G2-4 and G0-1 was 0.9333,which manifested high genetic similarity between these two populations. The results of t-test showed that there was no significant difference in effective number of alleles per loci （Ae）,index of genetic diversity （H）,Shannon＇s information index （I） between the control G0-1 and G1-1,G2-1,G1-2,and G2-2. The index values of Ae,H,and I for the populations of G0-3,G0-4,G1-3,G1-4,G2-3,and G2-4 declined significantly compared with those of the control G0-1. The number of rare alleles for the populations G1-1,G2-1,G1-2,and G2-2 did not change significantly compared with that for the control G0-1 while that for populations of G0-3,G0-4,G1-3,G1-4,G2-3,and G2-4 declined greatly. Above results showed that the genetic diversity and the number of rare alleles for the descendant population of the populations with 98.0% and 95.0% germination percentages did not change significantly compared with those for the control G0-1,but declined significantly for the populations with 81.0% and 79.0% germination percentages. Therefore,the viability decline had a greater impact on the genetic composition of soybean population than the regeneration times. It was recommended that soybean seeds with initial germination percentage of 98.0% should be regenerated before its germination percentage declined to 81.0%.