Genetic diversity of Typha latifolia (Typhaceae) and the impact of pollutants examined with tandem‐repetitive DNA probes

Abstract

Genetic diversity at variable-number-tandem-repeat (VNTR) loci was examined in the common cattail, Typha latifolia (Typhaceae), using three synthetic DNA probes composed of tandemly repeated "core" sequences (GACA, GATA, and GCAC). The principal objectives of this investigation were to determine whether: (1) the previously reported almost complete lack of polymorphism at allozyme loci in this species was indicative of a reduced amount of genetic diversity at VNTR loci as well; (2) VNTR markers were informative about possible clonal propagation; and (3) significant differences in genetic structure of sampling sites were associated with differences in environmental levels of pollutants at those sites. Previously, widespread sampling across the eastern United States, surveying across ten allozyme loci, has detected only two genotypes, involving a difference at a single locus, among 104 populations. In this study, the amount of genetic diversity detected at VNTR loci: (1) among ramets (N = 40; 40 genotypes detected) collected at ∼8-km intervals along a 320-km transect; (2) among ramets (N = 220; 117 genotypes detected) from five study sites separated by 50-3000 m; and (3) even among ramets within each study site [N = 44 per site; from 13 to 34 genotypes detected per site (270 m(2))] exceeds that previously found in those more geographically widespread allozyme surveys. Among the 260 ramets analyzed here, the mean number of bands scored per individual was 48.61 (SD = 2.80). Mean genetic similarity among ramets collected along the 320-km transect was 0.91, which was within the range of mean genetic similarity within the five study sites (range: 0.89-0.95). Among the five study sites, 61% of the samples analyzed appeared to be clonal ramets, with up to 12 clones detected for 44 ramets sampled within a site. Clones grew intermingled and ranged up to 39 m in extent. Permutation tests of genetic similarity revealed significant genetic differentiation between each of the five study sites. Consistent with the previous allozyme studies, T. latifolia was characterized by extremely low genetic variation relative to levels of polymorphism detected at VNTR loci in other plant species. Estimated heterozygosity among ramets along the 320-km transect ranged from 0.11 to 0.13, while that within the five study sites ranged from 0.05 to 0.12. Estimates of F(st) (0.32-0.41) also indicated considerable genetic subdivision among these stands. Significantly higher genetic diversity was detected at the two study sites that chemistry and toxicity data indicate to be the most severely impacted by pollutants. Although this correlation does not establish cause and effect, the results of this study indicate that the analysis of genetic diversity at VNTR loci may be a useful tool for monitoring anthropogenic-induced changes in the genetic structure of natural populations of plants.

Assessment of genetic diversity of Typha angustifolia in the development of cattail stands

“…Even though we could not conduct chemical analyses of the water and soil samples, the cattail stands were possibly exposed to chemical pollutants such as pesticides from the adjacent agronomic system. It is known that significantly higher genetic diversity of T. latifolia is related to exposure to pollutants (Keane et al 1999). However, the results of this study could not reveal the direct cause for the significantly high genetic diversity of ST 5.…”

“…Although many studies have been performed on cattail genetic diversity, such as the spatial distribution of genetic diversity, interspecific comparison of genetic diversity, and the potential for interspecific hybridization (Keane et al 1999, Selbo and Snow 2004, Tsyusko et al 2005, TillBottraud et al 2010, few studies have been conducted on genetic diversity changes during the development of subdivided cattail stands. Therefore, in this study, the extent and differences in genetic variation among Typha angustifolia stands within a small area were investigated using random amplification of polymorphic DNA-polymerase chain reaction to evaluate the changes in genetic diversity of T. angustifolia during stand development in the same population.…”

Mating system and genetic diversity of a rare desert legume Ammopiptanthus nanus (Leguminosae)

“…However, in the case of A. nanus, AFLP markers unexpectedly failed to detect more genetic variation than ISSR markers. Similarly, comparable frequencies of polymorphic markers and levels of heterozygosity were detected in Typha latifolia L. by Lamote et al (2005) using AFLP markers and Keane et al (1999) using variable number of tandem repeat (VNTR) markers. These findings were partly attributed to the low level of genetic diversity in the species analyzed (Lamote et al, 2005).…”

Analysis of the genetic variability and structure of Ochlerotatus taeniorhynchus (Diptera: Culicidae) populations from the Colombian Atlantic coast on the basis of random amplified polymorphic DNA markers

“…In contrast and in agreement with our results, other organisms have shown similar levels of genetic heterogeneity in isoenzymes, RAPDs, and microsatellites. This was the case observed in Typha latifolia (Keane et al, 1999) and several wild cereals (Li et al, 1999).…”