Multilocus nSSR genotypes and conservation genetics of a Tertiary relict “living fossil” tree: Parrotia persica (Hamamelidaceae)

Résumé fourni par la source

Parrotia persica (Hamamelidaceae) is a Tertiary relict “living fossil” tree endemic to Hyrcanian forest of Iran and Azerbaijan and in risk of extinction. Fossil evidence indicated P. persica diverged from its East Asian sister species P. subaequalis during the Miocene. To date, the genetic diversity and spatial genetic structure of P. persica remain largely unclear, which hinders the conservation of this threatened species. In this study, we first identified 5,459 candidate polymorphic nuclear microsatellite (nSSR) loci of P. persica via CandiSSR. Among those nSSRs, di-nucleotide (78.60%) and tri-nucleotide (16.34%) repeats were the most abundant, and 24 polymorphic nSSRs were then used to genotype 638 individuals of P. persica from 37 populations to estimate genetic diversity and population structure. Our results revealed that P. persica exhibited moderate level of genetic diversity ( H E = 0.485), low genetic differentiation ( F ST = 0.024; G’ST = 0.041) and high gene flow ( N m = 10.167) among populations. The P. persica population genetic structure could be divided into two gene pools, corresponding to two evolutionarily significant units (ESUs) in a clear spatial pattern of east vs. west of the Hyrcanian forest. Significant IBD (isolation by distance) effect was also examined in the two ESUs. We propose urgent in situ and ex situ conservation strategies for the long-term preservation for the rare “living fossil” P. persica . Notably, higher cross species transferability of our newly developed nSSRs was proven on P. subaequalis and other closely related species in Hamamelidaceae. Taken together, our research provides genetic resources for future studies of population genetics, molecular breeding, germplasm management and planning scientific conservation strategies and schemes for P. persica and other Hamamelidaceae species.

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