Genetic Diversity of the Endangered Dalbergia odorifera Revealed by SSR Markers

Abstract

Dalbergia odorifera T. Chen (Fabaceae) is a semi-deciduous tree species indigenous to Hainan Island in China. Due to its precious heartwood “Hualimu (Chinese)” and Chinese medicinal components “Jiangxiang”, D. odorifera is seriously threatened of long-term overexploitation and has been listed on the IUCN (International Union for Conservation of Nature’s) red list since 1998. Therefore, the elucidation of its genetic diversity is imperative for conservation and breeding purposes. In this study, we evaluated the genetic diversity of 42 wild D. odorifera trees from seven populations covering its whole native distribution. In total, 19 SSR (simple sequence repeat) markers harbored 54 alleles across the 42 samples, and the medium genetic diversity level was inferred by Nei’s gene diversity (0.36), observed (0.28) and expected heterozygosity (0.37). Among the seven wild populations, the expected heterozygosity (He) varied from 0.31 (HNQS) to 0.40 (HNCJ). The analysis of molecular variance (AMOVA) showed that only 3% genetic variation existed among populations. Moderate population differentiations among the investigated populations were indicated by pairwise Fst (0.042–0.115). Structure analysis suggested two clusters for the 42 samples. Moreover, the seven populations were clearly distinguished into two clusters from both the principal coordinate analysis (PCoA) and neighbor-joining (NJ) analysis. Populations from Haikou city (HNHK), Baisha autonomous county (HNBS), Ledong autonomous county (HNLD), and Dongfang city (HNDF) comprised cluster I, while cluster II comprised the populations from Wenchang city and Sansha city (HNQS), Changjiang autonomous county (HNCJ), and Wuzhisan city (HNWZS). The findings of this study provide a preliminary genetic basis for the conservation, management, and restoration of this endemic species.

Genetic Diversity and Population Genetic Structure of Cinnamomum camphora in South China Revealed by EST-SSR Markers

“…Our results indicated only a medium genetic diversity level in 41 C. camphora populations from China (Ho range from 0.30 to 0.61 and He range from 0.31 to 0.48). This is consistent with the different populations [46] and population size used in those studies [21].…”

“…Generally, the genetic diversity of species with a widespread distribution is higher than that of species with a narrow or endemic distribution [47,48]. Considering that the native habitant of C. camphora is widespread in the whole region of South China, it is not surprising that the genetic diversity in this study (Ho = 0.45 and He = 0.40) is much higher than that of other narrow or endemic species, such as Dalbergia odorifera (Ho = 0.28 and He = 0.37) [21], Gastrodia elata (Ho = 0.05 and He = 0.46) [24], and Ottelia acuminata (Ho = 0.28 and He = 0.37) [49]. However, the genetic diversity of C. camphora is much lower than that of other widespread tree species, such as Xanthoceras sorbifolia (Ho = 0.72 and He = 0.53) [50], Albanian olive (Ho = 0.75 and He = 0.60) [51], and Eugenia dysenterica DC.…”

“…Molecular markers are often used to investigate the genetic diversity and population genetic structure in tree species, especially for those species with less genetic information [21][22][23][24][25]. SSR markers are the ideal choices for wild tree populations because of their high variability and codominance [26,27].…”

Phylogeography of the rare and endangered lycophyteIsoetes yunguiensis

“…In the present study, I. yunguiensis showed high genetic diversity compared with other rare, endemic, and endangered plants, such as Isoetes sinensis Palmer (He = 0.118; Kang, Ye & Huang, 2005) Liu et al, 2019), and Brasenia schreberi J. F. Gmelin (He = 0.256; Li et al, 2018). Most rare and endangered plants are seed plants that can achieve a higher gene flow via long-distance pollen and seed dispersal than ferns that rely solely on spores.…”

Research in Forest Biology in the Era of Climate Change and Rapid Urbanization

“…Structure analysis suggests two clusters for the 42 samples. These findings provide a preliminary genetic basis for the conservation, management, and restoration of this endemic species [9].…”