Papers by Isabel Roldán-ruiz
Annals of Anatomy - Anatomischer Anzeiger, 2012
Wild apples (Malus sp.) have been a major food source in the northern Alpine region since prehist... more Wild apples (Malus sp.) have been a major food source in the northern Alpine region since prehistory and their use is well understood. The onset of deliberate fruit tree growing in the area is, however, less clear. It is generally assumed that horticulture was practised in Roman times, but it might be even earlier. In the archaeological record seed testa and pericarp remains are particularly frequent at sites with waterlogged preservation such as lakeshore settlements or wells, pits and ditches, but the distinction between wild and domestic plants is not morphologically possible. With waterlogged remains being one main source of information about past fruit cultivation, we have tested the feasibility of analysing ancient DNA from waterlogged preserved bulk samples of testa fragments. We studied apple seeds from three Neolithic and three Roman sites with waterlogged preservation in the Alpine foreland. Chloroplast markers failed in all samples, but nuclear ITS1 (internal transcribed spacer region 1) of the ribosomal DNA was successfully typed in two Roman samples from the site Oedenburg/Biesheim-Kunheim (Haut-Rhin, F). The retrieved ITS1 sequences are identical to each other and are shared with wild Malus sylvestris and Malus sieversii, and with domestic apple cultivars, supporting the potential of using waterlogged remains for identifying the genetic status of apple diachronically.
Sustainable use of Genetic Diversity in Forage and Turf Breeding, 2010
Members of the grass family are important as resource for the production of first generation bio-... more Members of the grass family are important as resource for the production of first generation bio-ethanol, which is based on the fermentation of starch and sucrose which is obtained from food crops like corn (US), wheat (Europe) or sugarcane (Brazil). If Europe wants to meet the objective of the new directive on the promotion of the use of energy from renewable sources, it will be necessary to make the transition from first to second generation conversion technologies for the production of bio-ethanol. These conversion techniques are based on the use of recalcitrant lignocellulosic biomass as feedstock. The energy contained in lignocellulosic biomass is largely entrapped in the plant cell wall, which is built up of cellulose, hemicellulose and lignin and can make up to 70% of the total plant biomass. To be able to produce ethanol from these rigid cell walls, the cellulose and hemicellulose need to be degraded first into monosaccharides. For the moment, this degradation constitutes a bottleneck in the process. Especially lignin is a disturbing factor. Therefore, an interesting approach to improve lignocellulosic crops is to reduce their lignin content. In this study, we use Brachypodium distachyon as a model to study the effect of up-or down regulation of genes with a key-role in the monolignol biosynthesis pathway on the saccharification efficiency. The general strategy and preliminary results of this study will be discussed.
Euphytica, 2002
Several genotypes of Lolium perenne (2n = 2x = 14) were screenedfor the production of 2n eggs. In... more Several genotypes of Lolium perenne (2n = 2x = 14) were screenedfor the production of 2n eggs. In each cross a diploid genotype, used asfemale parent, was pollinated with a tetraploid genotype. All interploidycrosses were made in isolation cages. Flow cytometrical analysis of theprogeny of 154 diploid plants revealed 28 tetraploid descendants. Theseoffspring plants were harvested on 15 different diploid
Aquatic Botany, 2005
We investigated to what extent DNA-markers can assist species determination in the genus Typha. A... more We investigated to what extent DNA-markers can assist species determination in the genus Typha. A set of AFLP markers was used to discriminate samples of the species Typha latifolia and Typha angustifolia collected in Flanders (North Belgium). The T. latifolia samples formed a compact cluster while the T. angustifolia samples were divided into smaller groups. It was not clear whether
Aquatic Botany, 2002
We used amplified fragment length polymorphisms (AFLPs) to conduct a study of the genetic diversi... more We used amplified fragment length polymorphisms (AFLPs) to conduct a study of the genetic diversity of Flemish populations of Iris pseudacorus in two hydrologically isolated river basins. AFLP analysis using four primer combinations was carried out on 88 different ramet samples, collected at nine different locations. A total of 148 polymorphic markers were scored. Samples from the basin of the
Molecular Ecology Notes, 2005
We characterize thirteen polymorphic microsatellite loci isolated from Naja atra genomic librarie... more We characterize thirteen polymorphic microsatellite loci isolated from Naja atra genomic libraries, which were enriched for AC-motif microsatellites. The thirteen loci were screened on a group of 48 individuals from two populations, one in Yong'an and the other in Ganzhou. These markers revealed a relatively high degree of genetic diversity (4-12 alleles per locus) and heterozygosity (Ho ranged from 0.213-0.854 and He ranged from 0.301-0.838). Tests for departure from Hardy-Weinberg equilibrium and for linkage disequilibrium were conducted for each of the two populations separately. After sequential Bonferroni correction, none of the 13 loci showed significant departures from Hardy-Weinberg equilibrium. Hierarchical analysis of molecular variance indicated that a small but significant (P < 0.001) proportion (16.0%) of the total variation in the microsatellite DNA data were attributable to differences among populations, indicating geographical structuring and restricted gene flow. It could be attributable to the Wuyi mountains in the area having a sufficiently isolating effect to significantly reduce gene flow. Our microsatellite data also showed a low N m (1.31) value in the two populations from mainland China. Thus, the Yong'an and Ganzhou populations could be treated as distinct evolutionarily significant units (ESUs). The high level of polymorphism revealed
Sustainable use of Genetic Diversity in Forage and Turf Breeding, 2010
Lignocellulosic biomass is a renewable carbon source and can significantly contribute to a reduct... more Lignocellulosic biomass is a renewable carbon source and can significantly contribute to a reduction of the use of fossil resources for the production of energy, chemicals and materials. Lignocellulose serves as feedstock ao for the production of energy (by direct ...
Sustainable use of Genetic Diversity in Forage and Turf Breeding, 2010
Abstract Mixed grass-clover grasslands are an essential element of sustainable farming systems. T... more Abstract Mixed grass-clover grasslands are an essential element of sustainable farming systems. The presence of clover in the mixture contributes significantly to the reduction of nitrogen fertilizer application needs, and results in improved nutri-tional value. In red clover, ...
To cite th is article / Pou r citer cet article etic diversity of Fu sariu m h ead bligh t QTLs a... more To cite th is article / Pou r citer cet article etic diversity of Fu sariu m h ead bligh t QTLs amon g Western Eu ropean wh eat.
Molecular Ecology Notes, 2005
We report on the characterization and mapping of 76 simple sequence repeat (SSR) markers for Loli... more We report on the characterization and mapping of 76 simple sequence repeat (SSR) markers for Lolium perenne . These markers are publicly available or obtained either from genomic libraries enriched for SSR motifs or L. perenne expressed sequence tag (EST) clones. Four L. perenne mapping populations were used to map the SSR markers. A consensus linkage map of the four mapping populations containing 65 of the SSR markers is presented, together with primer information and a quality score indicating the usefulness of the SSR marker in different populations. The SSR markers identified all seven L. perenne linkage groups.
Molecular Breeding, 2000
In this study the morphological and protein diversity of twelve diploid perennial ryegrass access... more In this study the morphological and protein diversity of twelve diploid perennial ryegrass accessions (Lolium perenne L.) was examined. These accessions comprised five closely related groups, each containing an `initial variety' (IV) and one or more declared `essentially derived varieties' (EDV), with differing degrees of relatedness. `Essential derivation' is a legal concept relating to intellectual property in plant varieties and
Plant methods, 2014
In grasses, leaf growth is often monitored to gain insights in growth processes, biomass accumula... more In grasses, leaf growth is often monitored to gain insights in growth processes, biomass accumulation, regrowth after cutting, etc. To study the growth dynamics of the grass leaf, its length is measured at regular time intervals to derive the leaf elongation rate (LER) profile over time. From the LER profile, parameters such as maximal LER and leaf elongation duration (LED), which are essential for detecting inter-genotype growth differences and/or quantifying plant growth responses to changing environmental conditions, can be determined. As growth is influenced by the circadian clock and, especially in grasses, changes in environmental conditions such as temperature and evaporative demand, the LER profiles show considerable experimental variation and thus often do not follow a smooth curve. Hence it is difficult to quantify the duration and timing of growth. For these reasons, the measured data points should be fitted using a suitable mathematical function, such as the beta sigmoid...
Journal of Agricultural and Food Chemistry, 2007
The concentrations of R-acids, -acids, desmethylxanthohumol, and xanthohumol were monitored in th... more The concentrations of R-acids, -acids, desmethylxanthohumol, and xanthohumol were monitored in the hop varieties Admiral (A), Wye Challenger (WC), and First Gold (FG) during the harvest seasons of 2003 through 2005. Hops grown under an organic regimen were compared to plants grown conventionally in hop fields in close vicinity. The concentrations of the key compounds depended very much on climatological conditions showing, in general, highest levels in poorest weather conditions (2004). Of the three varieties studied, FG was the only one showing a clear trend for higher concentrations of secondary metabolites under organic growing conditions than under conventional farming conditions. Cultivation of A and WC seems to be very sensitive to climatic conditions and environmental stresses caused by pests and diseases, thereby leading to various results. WC proved to be a rich source of bioactive chalcones, particularly desmethylxanthohumol.
Trends in Genetics, 2014
The cultivated apple is a major fruit crop in temperate zones. Its wild relatives, distributed ac... more The cultivated apple is a major fruit crop in temperate zones. Its wild relatives, distributed across temperate Eurasia and growing in diverse habitats, represent potentially useful sources of diversity for apple breeding. We review here the most recent findings on the genetics and ecology of apple domestication and its impact on wild apples. Genetic analyses have revealed a Central Asian origin for cultivated apple, together with an unexpectedly large secondary contribution from the European crabapple. Wild apple species display strong population structures and high levels of introgression from domesticated apple, and this may threaten their genetic integrity. Recent research has revealed a major role of hybridization in the domestication of the cultivated apple and has highlighted the value of apple as an ideal model for unraveling adaptive diversification processes in perennial fruit crops. We discuss the implications of this knowledge for apple breeding and for the conservation of wild apples.
TAG Theoretical and Applied Genetics, 2001
The comparison of different methods of estimating the genetic diversity could define their useful... more The comparison of different methods of estimating the genetic diversity could define their usefulness in plant breeding and conservation programs. In this study, a total of 15 morphological traits, eight AFLPprimer combinations and 20 simple sequence repeat (SSR) loci were used (i) to study the morphological and genetic diversity among 62 selected highland maize accessions, (ii) to assess the level of correlation between phenotypic and genetic distances, and (iii) to classify the accessions into groups based on molecular profiles and morphological traits. The analysis of variance of the morphological data revealed significant differences among accessions for all measured traits. The mean morphological dissimilarity (0.3 with a range of 0.1-0.68) was low in comparison to dissimilarity calculated using SSR markers (0.49 with a range 0.27-0.63) and AFLP markers (0.57 with a range 0.32-0.69). The correlation between the morphological dissimilarity matrix and the matrices of genetic dissimilarity based on SSR and AFLP markers was 0.43 and 0.39, respectively (p = 0.001). The correlation between SSRs and AFLPs dissimilarity matrices was 0.67 (p = 0.001). This congruence indicates that both marker systems are equally suited for genetic diversity study of maize accessions. Cluster analysis of morphological and marker distances revealed three groups of maize accessions with distinctive genetic profiles and morphological traits. This information will be useful for collections, conservation and various breeding programs in the highlands of Ethiopia.
![Research paper thumbnail of AFLP markers demonstrate local genetic differentiation between two indigenous oak species [ Quercus robur L . and Quercus petraea (Matt.) Liebl .] in Flemish populations](https://attachments.academia-assets.com/42441443/thumbnails/1.jpg)
TAG Theoretical and Applied Genetics, 2002
The nuclear genetic variation within and between four sessile (Q. petraea) and six pedunculate (Q... more The nuclear genetic variation within and between four sessile (Q. petraea) and six pedunculate (Q. robur) autochthonous Flemish oak populations was investigated with AFLP markers. One sessile and one pedunculate oak population were additionally screened for detailed leaf characteristics using an image analysis system. Principal coordinate analysis on the AFLP data classified the oaks in two main groups, according to their taxonomic status. No species-specific AFLP markers were found using four primer combinations, but marker frequency differences up to 71% were recorded between both species. Analysis of the genetic structure showed that the divergence between species, as observed by ordination, was significant. Both species revealed similar diversity levels. A smaller though significant differentiation was also revealed for both species among populations within species. Molecular and morphology based approaches showed a high degree of consistency. Screening of 60 AFLP primer combinations using a bulking strategy did not allow identifying species-specific markers, which supports the conclusions reached in previous studies. The distribution of genetic variability at the species and at the population level is discussed.
Theoretical and Applied Genetics, 2008
PLoS Genetics, 2012
The apple is the most common and culturally important fruit crop of temperate areas. The elucidat... more The apple is the most common and culturally important fruit crop of temperate areas. The elucidation of its origin and domestication history is therefore of great interest. The wild Central Asian species Malus sieversii has previously been identified as the main contributor to the genome of the cultivated apple (Malus domestica), on the basis of morphological, molecular, and historical evidence. The possible contribution of other wild species present along the Silk Route running from Asia to Western Europe remains a matter of debate, particularly with respect to the contribution of the European wild apple. We used microsatellite markers and an unprecedented large sampling of five Malus species throughout Eurasia (839 accessions from China to Spain) to show that multiple species have contributed to the genetic makeup of domesticated apples. The wild European crabapple M. sylvestris, in particular, was a major secondary contributor. Bidirectional gene flow between the domesticated apple and the European crabapple resulted in the current M. domestica being genetically more closely related to this species than to its Central Asian progenitor, M. sieversii. We found no evidence of a domestication bottleneck or clonal population structure in apples, despite the use of vegetative propagation by grafting. We show that the evolution of domesticated apples occurred over a long time period and involved more than one wild species. Our results support the view that self-incompatibility, a long lifespan, and cultural practices such as selection from open-pollinated seeds have facilitated introgression from wild relatives and the maintenance of genetic variation during domestication. This combination of processes may account for the diversification of several long-lived perennial crops, yielding domestication patterns different from those observed for annual species.
Plant Systematics and Evolution, 2009
Parasite populations do not necessarily conform to expected patterns of genetic diversity and str... more Parasite populations do not necessarily conform to expected patterns of genetic diversity and structure. Parasitic plants may be more vulnerable to the negative consequences of landscape fragmentation because of their specialized life history strategies and dependence on host plants, which are themselves susceptible to genetic erosion and reduced fitness following habitat change. We used AFLP genetic markers to investigate the effects of habitat fragmentation on genetic diversity and structure within and among populations of hemiparasitic Viscum album. Comparing populations from two landscapes differing in the amount of forest fragmentation allowed us to directly quantify habitat fragmentation effects. Populations from both landscapes exhibited significant isolation-by-distance and sex ratios biased towards females. The less severely fragmented landscape had larger and less isolated populations, resulting in lower levels of population genetic structure (F ST = 0.05 vs. 0.09) and inbreeding (F IS = 0.13 vs. 0.27). Genetic differentiation between host-tree subpopulations was also higher in the more fragmented landscape. We found no significant differences in withinpopulation gene diversity, percentage of polymorphic loci, or molecular variance between the two regions, nor did we find relationships between genetic diversity measures and germination success. Our results indicate that increasing habitat fragmentation negatively affects population genetic structure and levels of inbreeding in V. album, with the degree of isolation among populations exerting a stronger influence than forest patch size.
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Papers by Isabel Roldán-ruiz