Genetic diversity in perennial ryegrass and white clover among old Dutch grasslands as compared to cultivars and nature reserves

Abstract

To support conservation policies for old Dutch grasslands that are still in agricultural use, morphological variation and AFLP-based (amplified fragment length polymorphism-based) genetic diversity was studied in perennial ryegrass and white clover populations and compared with the diversity in reference varieties. In addition, AFLP variation was also studied in grasslands located in nature reserves. From principal component analysis (PCA), it appeared that date of ear emergence in perennial ryegrass and characters related to plant vigour in white clover were the main morphological characters separating the reference varieties from the old Dutch grassland populations, and some of the grassland populations from each other. In both species, intrapopulation variation was lower for the reference varieties. Lower heterogeneity within the reference varieties was also found in the AFLP analysis. All common AFLP's observed in old Dutch grasslands could also be found in the reference varieties and nature reserves. Only a small number of low-frequency alleles found in old Dutch grasslands were absent from the other two groups. However, band frequencies of markers could vary considerably between populations, which may have been caused by selection. Analysis of the AFLP data by PCA distinguished the majority of reference varieties from the old Dutch grasslands, and showed genetic differentiation only between some grasslands. Comparison of old Dutch grasslands with grasslands in nature reserves indicated that basically the same range of genetic variation is covered by the two groups. Our study indicates that the Netherlands harbour a more or less continuous population for major parts of the diversity of perennial ryegrass and white clover. It was concluded that no specific conservation measures are presently needed to maintain genetic diversity of perennial ryegrass and white clover occurring in old Dutch grasslands.

Towards an optimal sampling strategy for assessing genetic variation within and among white clover (Trifolium repens L.) cultivars using AFLP

“…In addition to the 45 field samples, leaf samples were collected from 30 greenhouse-sown seedlings of each cultivar. Up to that time, the 75 samples of each variety used to investigate appropriate sample size was more than the norm in studies of genetic diversity in white clover (Kölliker et al , 2001; Gustine and Elwinger, 2003; Van Treuren et al , 2005; Bortolini et al , 2006; Rizza et al , 2007). …”

“…Even so, studies of white clover genetic diversity have been inapt at explicitly optimizing sample sizes or verifying sampling effectiveness (Kölliker et al , 2001; Gustine and Elwinger, 2003; Van Treuren et al , 2005; Bortolini et al , 2006; Rizza et al , 2007). Herein, an investigation was undertaken of the impact of both sample size and the sampling scheme, on assessing genetic diversity within and among white clover cultivars.…”

Implementation of Molecular Markers Diversity in Parental Selection of Alfalfa (Medicago SativaL.) Germplasm

“…Molecular markers offer numerous advantages over conventional phenotype-based markers due to the following characteristics: they are stable and detectable in all tissues regardless of growth, differentiation, development, or defence status of the cell; they are not confounded by the environment, pleiotropic and epistatic effects; they are polymorphic and evenly distributed throughout the genome; they are simple, quick and inexpensive and need small amounts of tissue and DnA samples; they have linkage to distinct phenotypes and require no prior information about the genome of an organism (1,18). Various molecular marker types have been widely used to assess genetic diversity, to identify germplasm or to characterize population structures in alfalfa and other perennial forage crops (2,4,7,8,10,16,19,20,27,31). however, the published papers on implementation of data obtained by molecular marker analyses to practical breeding are quite limited.…”

Variation in effective pollination rates in relation to the spatial and temporal distribution of pollen release in rejuvenated perennial ryegrass

“…Amplified fragments were separated on 6% denaturing polyacrylamide gels. Further details about the AFLP procedures are presented by Van Treuren et al (2005).…”