|Elwinger, Gerald - USDA-NRCS|
Submitted to: American Society of Agronomy Branch Meeting
Publication Type: Abstract Only
Publication Acceptance Date: June 27, 2003
Publication Date: October 19, 2003
Citation: Gustine, D.L., Elwinger, G.F., Sanderson, M.A. 2003. Molecular analysis of genetic structure in grazed white clover populations [Abstract]. American Society of Agronomy Branch Meeting. p. 19. Technical Abstract: White clover (Trifolium repens L.) populations spread by vegetative growth, exhibit high genetic and clonal diversity, and often exist for many decades in grazed swards at northern midlatitudes. The genetic makeup of white clover (WC) populations undergoes complete turnover in less than two weeks. This study was conducted to determine whether genetic structure exists within rapidly changing populations in the field and is a factor in creating genetic diversity. Trifoliate leaf samples were taken monthly in 1997 and 1998 from up to 37 specific points in four 1.2 x 1.2 m quadrats from May to September on three central Pennsylvania farm sites. Randomly amplified polymorphic DNA (RAPD) profiles of population samples from quadrats were analyzed by analysis of molecular variance (AMOVA) and tested by spatial autocorrelation analysis based on multivariate nonparametric approaches. AMOVA indicated genetic variability was dynamic at the local scale. Significant (P < 0.05) overall spatial autocorrelation was found in 26 populations that had clones and in seven populations without clones, while no significant autocorrelation was found in 27 and seven populations with and without clones, respectively. Number of clones and patch size was less important in determining genetic structure than variable existence of spatial autocorrelation. During the study, numbers of clonal members increased or decreased and some clones were found on two or three dates of harvest. Our data show that clones in WC populations undergo dynamic spatial and temporal variability at a local scale as they do at the regional scale.