Microsatellite markers indicate genetic differences between cultivated and natural populations of endangeredTaxus yunnanensis

Abstract

Taxus yunnanensis (Taxaceae) is an endangered plant known for its effective natural anti-cancer metabolite, taxol. To assess the effectiveness of T. yunnanensis ex situ conservation in China, the genetic diversity and genetic structure of nine cultivated and 14 natural populations were compared using 11 polymorphic microsatellite markers. The purpose of this comparison was to determine whether the cultivated populations were genetic representatives of natural types. Among the 14 natural populations studied, three were from Tibet and 11 were from the Hengduan Mountains. There were fewer genetic variations among cultivated populations than among natural populations, but this difference was not significant. However, 23 unique alleles were detected in cultivated populations and 14 were detected in natural populations. Striking differences in genetic structure (GST = 0.365) was observed between them. STRUCTURE, AMOVA and cluster analyses also consistently showed a clear genetic separation between the 14 natural and seven cultivated populations. Only five natural populations from the south-central Hengduan Mountains were genetically represented in two cultivated collections. The reason for the occurrence of distinct genetic differences between cultivated and natural populations and the loss of natural population-specific alleles in the cultivated populations can be attributed to uneven selection during establishment. These results suggest that the genetic structure of T. yunnanensis may not have been conserved effectively. Based on our study, practical conservation strategies for ex situ preservation of T. yunnanensis have been developed.

Meta‐analysis of genetic representativeness of plant populations under ex situ conservation in contrast to wild source populations

“…3). Because of the small population sizes, increased spatial isolation, and artificial selection caused by incomplete sampling strategies, high levels of ex-situ-wild F ST have been reported in several empirical studies, even between ex situ populations and the wild populations where they were collected (Lauterbach et al 2012;Miao et al 2015;Müller et al 2017). Furthermore, the effect size of ex-situwild F ST significantly increased as the duration of ex situ conservation increased (Fig.…”

“…Inbreeding coefficient also exhibits mixed results among ex situ conservation genetic studies (Aavik et al 2012;Yokogawa et al 2013). Furthermore, the levels of genetic differentiation among ex situ populations (among-ex-situ F ST ) or between ex situ and wild populations (ex-situ-wild F ST ) are similar or higher compared with those among wild populations (among-wild F ST ) (Li et al 2005;Lauterbach et al 2012;Yokogawa et al 2013;Miao et al 2015).…”

Low genetic diversity in the endangeredTaxus yunnanensisfollowing a population bottleneck, a low effective population size and increased inbreeding

“…Greater attention should also be paid to seed dormancy mechanisms. Miao et al (2015) found that individuals established by seed propagation had greater genetic diversity and contained more unique alleles than those that were vegetatively propagated. Similarly, Yang et al (2011) reported that the former tended to have greater numbers of prosperous roots, straighter trunks and stronger disease resistance than the latter.…”

“…In summary, the two natural T. yunnanensis populations investigated in this study were characterized by low genetic diversity following a population bottleneck, weak but significant SGS, extremely low effective population size and high inbreeding. To effectively conserve the genetic diversity of this species to maintain the adaptive potential under changing environmental conditions, in situ and ex situ conservation should be implemented (Miao et al, 2015), especially for the actual breeding individuals (Ne). Moreover, increasing the Ne can not only promote the quantity of expected heterozygosity (Ht), but also decrease the degree of inbreeding within a population based on the equation Ht/Ho = [1 -l/(2Ne)] t = 1 -F given by Falconer (1989).…”

Integration of multiple climate models to predict range shifts and identify management priorities of the endangered Taxus wallichiana in the Himalaya–Hengduan Mountain region

“…Subsequently, the effectiveness of taxol has been documented for the treatment of various cancers, inflammatory conditions, and Acquired Immune Deficiency Syndrome (Yan et al 2013;Yang et al 2017). As one of the most successful anticancer drugs derived from natural sources (Yang et al 2017), taxol has a huge and expanding market demand (Miao et al 2015). The bark and leaves of T. wallichiana are now used to produce taxol, and this is the reason for its exploitation (Thomas and Farjon 2011;Uniyal 2013).…”