Development of microsatellite markers for the apomictic triploid fern Myriopteris lindheimeri (Pteridaceae)

Abstract

Premise of the study:Microsatellite markers were developed for investigating the population dynamics of Myriopteris lindheimeri (Pteridaceae), an apomictic triploid fern endemic to deserts of the southwestern United States and Mexico.Methods and Results:Using 454 sequencing, 21 microsatellite markers were developed. Of these, 14 were polymorphic with up to five alleles per locus and eight markers amplified in one or more congeneric close relatives (M. covillei, M. fendleri, M. aurea, and M. rufa). To demonstrate marker utility, M. lindheimeri samples from three Arizona populations were genotyped at nine loci. For each population, diversity measures including percent polymorphic loci, frequency of heterozygotes across all loci, and genotypic diversity were calculated. Across the three populations, on average, 63% of loci were polymorphic, the average frequency of heterozygotes (across all loci) was 0.32, and average genotypic diversity was 0.34.Conclusions:These markers provide a foundation for future studies exploring polyploidy and apomixis in myriopterid ferns.

A current perspective on apomixis in ferns

“…Recent population surveys have used a variety of molecular tools to examine genotypic diversity in apomictic groups, including allozymes, simple sequence repeats (SSRs), inter-simple sequence repeats (ISSRs), and amplified fragment length polymorphisms (AFLPs). Their results support the claim that apomictic lineages have low levels of genotypic diversity across and, especially, within populations (e.g., in Myriopteris, Grusz & Pryer, 2015;and Dryopteris, Schneller & Krattinger, 2010;Peredo et al, 2013), particularly when compared to limited sampling of a single obligate outcrosser (i.e., Blechnum spicant; Peredo et al, 2013). However, extensive sampling of apomictic taxa within Cyrtomium (Ootsuki et al, 2011) revealed comparatively high genetic diversity in these lineages across Japan.…”

Using nuclear gene data for plant phylogenetics: Progress and prospects II. Next‐gen approaches

“…Initially, their development required a significant investment of time and resources (including DNA enrichment, cloning and Sanger sequencing steps) just for production of one to two dozen primer pairs that generated polymorphic fragment profiles (Glenn & Schable, ). Recently, however, next generation sequencing of whole genomes, even at low degrees of coverage from such high genome content species as ferns (Grusz & Pryer, ), has been shown to produce hundreds of primers that can amplify regions containing di‐, tri‐ and tetra‐nucleotide repeats with the use of software such as the programs MSATCOMMANDER (Faircloth, ), or MISA (Microsatellite identification tool, http://pgrc.ipk-gatersleben.de/misa/). Initially, because it produced significantly longer read lengths, the Roche 454 GS‐FLX Titanium platform was used for such studies (Zalapa et al, ) such as ones used to screen Schistosoma parasites (Glenn et al, ) and fava bean accessions (Yang et al, ).…”