关键词: 文冠果, 父本分析, SSR分子标记, 遗传多样性

Abstract:

Objective: In this study, SSR markers were used to identify the paternal origin of the open-pollinated progeny population of 5 high-yielding Xanthoceras sorbifolium (yellowhorn) varieties, and to explore suitable pollinator trees or pollinator varieties that can enhance the yield of specific yellowhorn varieties, thereby providing references for yellowhorn variety selection and high-yield cultivation. Method: A total of 395 progeny plants derived from the free pollination of 5 high-yielding yellowhorn varieties and 288 candidate male parents were used as materials. Based on the SSR markers developed by the team in the previous stage, a total of 17 SSR markers were screened out. Paternity identification was conducted through Cervus software, and genetic diversity analysis was carried out on the offspring population. Result: At a 95% confidence level, the paternal parent of 121 offspring was successfully identified. Both ‘Qiaoranboke’ and ‘Zhongshi No.4’ provided pollen for the mother trees. The paternal parent ‘Qiaoranboke’ and maternal parent ‘Zhongshi No.4’ had the most offspring, totaling 6 offspring. Among the 68 seedling-originated yellowhorn plants, 3 paternal origins produced the most offspring, totaling 15 offspring. The four yellowhorn trees with the numbers 12-150, 12-193, 6-144, and 6-107 had a high overall reproductive contribution rate and some of their pollen travelled a relatively long distance. The reproductive contribution rates of the yellowhorn with the numbers 12-141 and 6-161 to the maternal parent ‘Zhongshi No.9’ were 4.13% and 3.31%, respectively, and the reproductive contribution rate of the yellowhorn with the number 6-107 to the maternal parent ‘Qiaoranboke’ was 2.48%. Through paternal analysis, no self-pollinated offspring was detected, indicating that self-pollination in yellowhorn is extremely weak. The effective pollen dispersal distance of yellowhorn was 6?154.1 m, with an average distance of 54.67 m. Proximal pollen (<60 m) accounted for 62.28% of the total pollen sources. The average number of alleles, average effective number of alleles, average Shannon’s information index (I), average observed heterozygosity, and average expected heterozygosity were 8.706, 3.152, 1.308, 0.619, and 0.644, respectively. The polymorphic information content (PIC) ranged from 0.369 to 0.834, with an average of 0.588. Both population genetic structure and clustering analysis results indicated that the 395 yellowhorn germplasm samples were able to be divided into two major groups. Conclusion: The pollen sources of yellowhorn are relatively dispersed, and distance significantly affects the pollination rate of yellowhorn. The ‘Qiaoranboke’ cultivar is suitable as a pollinator for the ‘Zhongshi No.4’ cultivar. The yellowhorn trees numbered 12-150 and 12-193 are suitable as pollinators for the ‘Zhongshi No.1’ cultivar. The yellowhorn trees numbered 6-144, 9-200, and 6-107 are suitable as pollinators for ‘Zhongshi No.4’, ‘Zhongshi No.4’, and ‘Qiaoranboke’, respectively. The ‘Zhongshi No.4’ half-sib family exhibits the highest genetic diversity, while the ‘Yuandashuozhong’ half-sib family shows the lowest genetic diversity.

Key words: Xanthoceras sorbifolia, paternal analysis, SSR molecular markers, genetic diversity