JOURNAL OF NANJING FORESTRY UNIVERSITY ›› 2023, Vol. 47 ›› Issue (1): 145-153.doi: 10.12302/j.issn.1000-2006.202110049

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Genetic diversity and genetic structure of Tilia miqueliana population

WANG Huanli(), YAN Lingjun, HUANG Xi, WANG Zhongwei, TANG Shijie()   

  1. Institute of Botany Jiangsu Province and Chinese Academy of Science,Jiangsu Key Laboratory for the Research and Utilization of Plant Resources, Nanjing 210014, China
  • Received:2021-10-25 Accepted:2021-11-29 Online:2023-01-30 Published:2023-02-01
  • Contact: TANG Shijie E-mail:wanghuanli@cnbg.net;tangshijie69@aliyun.com

Abstract:

【Objective】 Tilia miqueliana is an important native tree species in Jiangsu Province, and its wild germplasm resources are particularly scarce. Exploration of the genetic diversity and the genetic structure of T. miqueliana in the field population provides the scientific basis for its resource protection, variety breeding and genetic improvement.【Method】 Fifteen polymorphic EST-SSR primers were used to analyze the genetic diversity and population structure of 93 individuals from five natural populations of T. miqueliana located on Baohua Mountain (Jiangsu Province, P1), Niushou Mountain (Jiangsu Province, P2), Huangcangyu Nature Reserve (Anhui Province, P3), Shu Mountain (Anhui Province, P4) and Tiantai Mountain (Zhejiang Province, P5). 【Result】 (1) A total of 96 alleles (A) were detected using 15 EST-SSR primer pairs. The average allelic richness at a locus was 6.4. The total number of tetraploid genotypic richness (G) and tetraploid specific genotypes (Gi) were 441 and 251, respectively. The average of the specific genotype ratio (R1) and the germplasm identification rate (R2) were 45.73% and 17.99%, respectively. (2) In the five populations, the mean number of alleles per locus (Aloc) and the tetraploid genotypic richness (Gloc) were 5.50 ± 2.43 and 9.41 ± 4.29, respectively. The mean observed heterozygosity (Ho) and the mean expected heterozygosity (He) were 0.61 ± 1.43 and 0.62 ± 0.14, respectively. Based on the values for Gloc and He, the P1 and P3 populations were identified as having high genetic diversity. (3) The genetic differentiation coefficient (Gst) was 0.030, indicating a low genetic differentiation among the five populations. Analysis of molecular variance (AMOVA) showed that the variation in genetic diversity predominantly came from within the population (96%). (4) Cluster analysis and genetic structure analysis by structure showed that the five tested populations could be divided into two groups (Group1. P1, P2 and P5; Group2. P3 and P4). The Mantel test results showed that there was no significant correlation between the genetic differentiation and the geographic distance. 【Conclusion】 High levels of genetic diversity were found within the five populations of T. miqueliana, among which Baohua Mountain population and Huangcangyu Nature Reserve population showed considerably higher genetic diversity than that the other populations showed. Combined with the results from the clustering and genetic structure analysis, we can infer that population expansion may have been centered on these two populations and migrated to other regions through human activities. There was no pronounced genetic differentiation among the different geographic populations, which may be due to the long life of individuals, the lack of natural regeneration of populations, and seed dispersal among populations through human activities. Therefore, we propose to establish isolation areas, identify priority populations for protection, increase plant outcrossing, and use artificial breeding and germplasm regeneration to protect the wild populations.

Key words: Tilia miqueliana, SSR marker, genetic structure, genetic diversity

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