Effects of Seed Viability and Number of Generations on Genetic Integrity of Soybean Germplasm Zhonghuang 18 by AFLP Markers

摘要：The seeds of a soybean cultivar Zhonghuang 18 were subjected to accelerated aging for 0 (population G 0-1), 112 (population G 0-2), 154 (population G 0-3) and 196 d (population G 0-4), whose germination percentage was found to be 98.0%, 95.0%, 81.0%, and 79.0%, respectively. Then, the four populations were regenerated twice in the field. The first descendant populations were marked as G 1-1, G 1-2, G 1-3 and G 1-4, and the second were marked as G 2-1, G 2-2, G 2-3 and G 2-4, respectively. The genetic variation between the control population (G 0-1) and the experimental populations was analyzed using 12 AFLP primer combinations. The results showed that there was no significant difference in genetic similarity between the 11 experimental populations and the control population G 0-1. The genetic similarity between population G 2-4 and G 0-1 was still as high as 0.933 3, indicating that the F 2 generation of the population whose germination percentage was only 79.0% still had a high genetic similarity to the control population. The results of t -tests revealed that the populations G 1-1, G 2-1, G 1-2 and G 2-2 showed no significant difference from the control population G 0-1 in effective number of alleles per locus (Ae), genetic diversity index (H) and Shannon s diversity index (I), while these indices of populations G 0-3, G 0-4, G 1-3, G 1-4, G 2-3 and G 2-4 were significantly reduced.χ 2 tests indicated that the populations G 1-1 and G 2-1 showed little difference, and the populations G 0-2, G 0-3, G 0-4, G 1-2, G 1-3, G 1-4, G 2-2, G 2-3, and G 2-4 showed great difference in allele frequency distribution from the control population G 0-1, and the difference was greater when the seed viability was lower. Compared with the control population G 0-1, the number of rare alleles (Nr) of the populations G 0-2, G 1-1, G 2-1, G 1-2 and G 2-2 showed no significant difference, while that of the populations G 0-3, G 0-4, G 1-3, G 1-4, G 2-3 and G 2-4 declined obviously. These results revealed that compared with the control