Genetic diversity and population structure analysis of Franklinia alatamaha, a tree species existing only in cultivation

• Published in: Tree genetics & genomes Vol. 16; no. 4
• Main Authors: Gladfelter, Heather J., Yadav, Lav K., Merkle, Scott A., Wilde, H. Dayton
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.08.2020; Springer Nature B.V
• Subjects: Biomedical and Life Sciences; Biotechnology; Coastal plains; Cultivation; Forestry; Franklinia alatamaha; Genetic analysis; Genetic diversity; Genotyping; Inbreeding; Life Sciences; Mathematical analysis; Nucleotides; Original Article; Ornamental plants; Plant Breeding/Biotechnology; Plant Genetics and Genomics; Plant species; Polymorphism; Population; Population genetics; Population structure; Seeds; Single-nucleotide polymorphism; Statistical analysis; Structural analysis; Subpopulations; Tea; Tree Biology; United States > US; Georgia; Gamma irradiation; Genetic diversity; Genotyping-by-sequencing; Polymorphism
• ISSN: 1614-2942; 1614-2950
• DOI: 10.1007/s11295-020-01455-x

Franklinia alatamaha is a small tree in the tea family (Theaceae) that has been valued for its ornamental qualities since 1765, when it was first recorded by John and William Bartram on the Georgia Coastal Plain. The only known population of F. alatamaha became extinct in the wild by the early 1800s. However, F. alatamaha has been cultivated as an ornamental for nearly 250 years. The plants existing today are derived from seeds collected from the Georgia population by the Bartrams. To examine the genetic variation of the cultivated F. alatamaha population, leaves from live and herbarium accessions were obtained from 42 sites worldwide. Genotyping-by-sequencing (GBS) was used to determine the genetic diversity and structure of 76  F. alatamaha accessions, including a 178-year-old herbarium specimen. STRUCTURE analysis with 9604 high-quality single-nucleotide polymorphisms (SNPs) identified two subpopulations within the cultivated accessions. This result was supported by UPGMA (unweighted pair group method with arithmetic mean) and principal component analyses. F statistics indicated that there was a moderate level of genetic diversity among the cultivated accessions ( F ST  = 0.09), with more genetic diversity among accessions within a subpopulation than between the two subpopulations. The inbreeding coefficient of the cultivated accessions was low ( F IS  = − 0.4902), indicating that the sampled trees represent what was once a highly outcrossing population. Polymorphism was also detected by GBS analysis of 19  F. alatamaha plants grown from gamma-irradiated seeds. The genetic differentiation identified in this study may be useful for further development of new horticultural traits of F. alatamaha .