Genetic diversity and geographic differentiation in Tacca chantrieri (Taccaceae): An autonomous selfing plant with showy floral display

Laboratory for Plant Biodiversity and Biogeography, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650204, China.
Annals of Botany (Impact Factor: 3.65). 09/2006; 98(2):449-57. DOI: 10.1093/aob/mcl123
Source: PubMed


Despite considerable investment in elaborate floral displays, Tacca chantrieri populations are predominantly selfing. It is hypothesized that this species might possess considerable spatial or temporal variation in outcrossing rates among populations. To test this hypothesis, genetic variability and genetic differentiation within and among T. chantrieri populations were investigated to find out if they are in agreement with expectations based on a predominantly inbred mating system.
Genetic diversity was quantified using inter-simple sequence repeats (ISSR) in 303 individuals from 13 populations taken from known locations of T. chantrieri in China, and from one population in Thailand.
Of the 113 primers screened, 24 produced highly reproducible ISSR bands. Using these primers, 160 discernible DNA fragments were generated, of which 145 (90.62 %) were polymorphic. This indicated considerable genetic variation at the species level. However, there were relatively low levels of polymorphism at population levels, with percentages of polymorphic bands (PPB) ranging from 8.75 % to 55 %. A high level of genetic differentiation among populations was detected based on different measures (Nei's genetic diversity analysis: G(ST) = 0.5835; AMOVA analysis: F(ST) = 0.6989). Furthermore, based on levels of genetic differentiation, the 14 populations clustered into two distinct groups separated by the Tanaka Line.
High levels of differentiation among populations and low levels of diversity within populations at large spatial scales are consistent with earlier small-scale studies of mating patterns detected by allozymes which showed that T. chantrieri populations are predominantly selfing. However, it appears that T. chantrieri has a mixed-mating system in which self-fertilization predominates, but there is occasional outcrossing. Significant genetic differences between the two distinct regions might be attributed to vicariance along the Tanaka Line. Finally, possible mechanisms of geographic patterns based on genetic differentiation of T. chantrieri are discussed.

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Available from: De-Zhu Li, Oct 07, 2015
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    • "Forrest et al. (2004) explained the strong differentiation found among European populations of Spiranthes romanzoffiana (Orchidaceae) (ΦST = 0.892) as resulting from the lack of gene flow between the evaluated populations, combined with different reproductive strategies across populations (autogamy, vegetative reproduction and crossing). Other works with autogamous species (Nybon and Bartish 2000; Xiao et al. 2006; Zhang et al. 2006; Voss et al. 2012; Aguayo et al. 2013 "
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    • "Using inter simple sequence repeat (ISSR) markers, we previously demonstrated that there is a strong genetic differentiation in T. chantrieri across eastern and western parts of the Tanaka line (Zhang et al., 2006), but the divergent time and the factors that resulted in the genetic differentiation of T. chantrieri between the two lineages were unclear. Here, we utilize chloroplast DNA variation of T. chantrieri distributed in tropical regions to elucidate phylogeographic patterns and demography of this species and then explore the possible causes that can explain the phylogeographic patterns of distribution in T. chantrieri. "
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    • "ISSR is a technique that overcomes most of these limitations [5,7]. This technology has been used to DNA fingerprint a wide range of crops [5,7,8–10] and to understand ploidy complex and the geographic origin of some plant species [11,12–16]. DNA profiling techniques that have been successfully used in assessing relatedness of Cynodon accessions includes DNA amplification fingerprinting (DAF) [17], RAPD [18,19], AFLP [20,21], ISSR [22], SSR [23] and chloroplast specific simple sequence repeat length polymorphism (CpSSRLP) [20]. "
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