Maintaining germplasm genetic integrity is a key objective of long-term ex situ conservation. Periodic regeneration, performed on limited plots with small number of individuals, increases the risk of genetic drift and genetic diversity changes. In this study, six accessions of white flowered, dry seed pea varieties (Pisum sativum L. subsp. sativum var. sativum): Bohatýr, Klatovský zelený, Hanák, Moravský hrotovický krajový, Raman and Viktoria-75 and four accessions of colour flowered, fodder pea (P. sativum subsp. sativum var. arvense (L.) Poiret: Arvika, Č eský banán, Moravská krajová and Niké, representing Czechoslovak varieties and landraces, bred over the last 40-80 years, were analyzed using ten microsatellite locus specific markers. Each accession was represented by 20 individual seeds of two temporally different samples, spanning the period of 20 or 40 years. Together with intra-accession variation (except of cv. Hanák), evidence of genetic changes, e.g. differences in allele frequencies as well as genetic composition of sample, was detected in six out of ten accessions (Arvika, Bohatýr, Č eský banán, Moravský hrotovický krajový, Moravská krajová and Raman). Evidence of genetic erosion was found in three accessions (Č eský banán, Moravský hrotovický krajový and Raman), while in another three (Arvika, Bohatýr and Moravská krajová) the level of diversity was found to have increased. Moreover in three samples of Bohatýr (2004) and Klatovský zelený (1963 and2004), low levels of heterozygosity was detected. These results demonstrate that in pea, a selfpollinating and highly homozygous plant, the danger of the loss of genetic integrity exists. These findings are significant for long-term ex situ germplasm management.

Genetic variability among 41 accessions of red pepper (<I>Capsicum annuum</I> L.) was assessed using eight microsatellite markers. Three of the microsatellite markers (<I>Hpms 1-1, Hpms 1-168, and Hpms 1-274</I>) had uniform spectra in all the analyzed plants. Two to eight alleles were detected for the remaining loci. In total, 28 alleles were detected, i.e. 3.5 alleles per one microsatellite locus on average. The highest number of different alleles was detected with <I>Hpms 1-5</I> (8 alleles) and <I>Hpms 2-21</I> primers (7 alleles). Molecular data were complemented with morphological measurements according to the descriptor list for the genus <I>Capsicum</I>. A dendrogram based on our genetic analysis suggests a high level of similarity between some of the accessions presumed to be distant and, at the same time, genetic variability between accessions of the same or similar name. These results show the possibility of duplicities in the current Czech collection of red pepper genetic resources.

Changes in genetic diversity of peas bred in the Czech Republic and in former Czechoslovakia since the mid-20 th century were analysed using 38 molecular marker loci, including retrotransposons and microsatellites, differentiating a total of 84 alleles. Both marker types were comparably effective in revealing the genetic diversity, with a high correlation (r = 0.81), although the pairwise genetic distances of each marker type differed. In total, 175 accessions, selected from the Czech pea gene bank collection and representing the pea cultivars collected or bred in the country, were divided into three groups according to their date of sampling or variety registration. The first group contained 70 old cultivars and landraces collected prior to 1961. The second group contained 46 cultivars released from 1961 to 1980. The third group contained 59 cultivars released between 1981 and 2004. In spite of the decline in several diversity measures, differences in allele frequencies and even allele loss in three microsatellite loci were recorded over the 70-year period, while these differences between the groups were not statistically significant. In addition, genetic heterogeneity was detected in 29 accessions (15%). This indicates that although no genetic erosion could be observed since then, it is important to monitor the genetic diversity, furthermore it highlights the vital role of germplasm collections for the crop diversity conservation.

Microsatellites, or simple sequence repeats (SSRs) are widespread class of repetitive DNA sequences, used in population genetics, genetic diversity and mapping studies. In spite of the SSR utility, the genetic and evolutionary mechanisms are not fully understood. We have investigated three microsatellite loci with different position in the pea (Pisum sativum L.) genome, the A9 locus residing in LTR region of abundant retrotransposon, AD270 as intergenic and AF016458 located in 5'untranslated region of expressed gene. Comparative analysis of a 35 pair samples from seven pea varieties propagated by single-seed descent for ten generations, revealed single 4 bp mutation in 10th generation sample at AD270 locus corresponding to stepwise increase in one additional ATCT repeat unit. The estimated mutation rate was 4.76 × 10(-3) per locus per generation, with a 95% confidence interval of 1.2 × 10(-4) to 2.7 × 10(-2). The comparison of cv. Bohatýr accessions retrieved from different collections, showed intra-, inter-accession variation and differences in flanking and repeat sequences. Fragment size and sequence alternations were also found in long term in vitro organogenic culture, established at 1983, indicative of somatic mutation process. The evidence of homoplasy was detected across of unrelated pea genotypes, which adversaly affects the reliability of diversity estimates not only for diverse germplasm but also highly bred material. The findings of this study have important implications for Pisum phylogeny studies, variety identification and registration process in pea breeding where mutation rate influences the genetic diversity and the effective population size estimates.