Low genetic differentiation among seasonal cohorts inSenecio vulgarisas revealed by amplified fragment length polymorphism analysis

Abstract

Common groundsel, Senecio vulgaris (Asteraceae), is a highly selfing semelparous ephemeral weed that belongs to the few plant species in central Europe capable of growing, flowering and fruiting all year round. In temperate climates, flowering S. vulgaris cohorts were found to appear up to three times per year. Using amplified fragment length polymorphism (AFLP) molecular markers we examined temporal genetic differentiation among spring, summer and autumn cohorts at each of seven sites located in two regions in Switzerland. Strong genetic differentiation among cohorts may indicate the existence of seasonal races of S. vulgaris, reproductively isolated by nonoverlapping flowering phenologies. Analysis of molecular variance (amova) revealed that < 2.5% of the AFLP variation resided among cohorts within sites, whereas there was significant genetic differentiation among plants from different sites (15.6%) and among individuals within cohorts (81.9%). Significant genetic differentiation was also observed between the two regions. Isolation-by-distance was found on a regional scale, but not on a local scale. Gene flow was estimated to be approximately 15-fold higher among cohorts within sites than among sites. We further found, on average, similar levels of genetic diversity within the three seasonal cohorts. The results of this study demonstrate that season of growth represents a weak barrier for genetic exchange among S. vulgaris populations and does not affect molecular variance. Therefore, there is no evidence for the existence of seasonally specialized races of S. vulgaris. We discuss some implications of the results for the biological control of S. vulgaris using a native rust fungus.

Functional significance of triazine-herbicide resistance in defence of Senecio vulgaris against a rust fungus

“…vulgaris, the accession used in our study, is reported to be nearly absent (Kadereit, 1984;Popay & Roberts, 1970). A recent molecular marker study at seven sites in two regions of Switzerland further showed that the three seasonal cohorts of S. vulgaris may simply arise from seed shed in the previous generation (Haldimann et al, 2003). Moreover, all S. vulgaris in the vicinity of our plots had been removed before the start and during our experiment, and plots had been fenced with a fine mesh to avoid cross-contaminations through seed dispersal.…”

“…vulgaris L. (Asteraceae), common groundsel, is a predominantly selfing, short-lived annual (Haldimann, Steinger, & Mu¨ller-Scha¨rer, 2003) that is common worldwide and often reported as a troublesome weed (Holm, Doll, Helm, Dancho, & Herberger, 1997). S. vulgaris was the first species to evolve herbicide resistance and TR populations have subsequently become common and widespread in Europe and North America (Holt & LeBaron, 1990).…”

Relationships of Zingiber species, and genetic variability assessment in ginger (Zingiber officinale) accessions from ex-situ genebank, on-farm and rural markets

“…High variance within group/population compared with among group/populations was also observed in sexually as well as asexually reproducing species (e.g. Sreekumar and Renuka 2005, Hangelbroek et al 2002, Haldimann et al 2003.…”

Testing the Evolution of Increased Competitive Ability (Eica) Hypothesis in a Novel Framework

“…DNA was extracted from fresh leaf tissue and AFLP analysis was carried out essentially as described by Haldimann et al (2003). However, after preselective polymerase chain reaction (PCR) amplification, fragments were amplified in a second selective multiplex PCR amplification by combining the fluorescent-labeled 5-FAM (EcoRI þ AGG) (Microsynth, Balgach, Switzerland), JOE (EcoRI þ ACC) (Microsynth), and TAMRA (EcoRI þ AGC) primers with the MseI þ CAA primer in a first reaction and then with the MseI þ CTT primer in a second reaction.…”