Epigenetics in plant tissue culture

Plants produced vegetatively in tissue culture may differ from the plants from which they have been derived. Two major classes of off-types occur: genetic ones and epigenetic ones. This review is about epigenetic aberrations. We discuss recent studies that have uncovered epigenetic modifications at the molecular level, viz., changes in DNA methylation and alterations of histone methylation or acetylation. Various studies have been carried out with animals, and with plant cells or tissues that have grown in tissue culture but only little work has been done with shoots generated by axillary branching. We present various molecular methods that are being used to measure epigenetic variation. In micropropagated plants mostly differences in DNA methylation have been examined. Epigenetic changes are thought to underlie various well-known tissue-culture phenomena including rejuvenation, habituation, and morphological changes such as flower abnormalities, bushiness, and tumorous outgrowths in, among others, oil palm, gerbera, Zantedeschia and rhododendron

Analysis of a database of DNA profiles of 734 hybrid tea rose varieties

Over 10,000 Hybrid Tea rose varieties have been described. The large number of varieties and the size of the reference collections may cause problems in DUS (Distinctiveness, Uniformity, and Stability) testing. Molecular markers may help to solve these problems by providing high power to identify and recognise seedling-derived varieties based on unique genotypes, while grouping mutants into groups with identical marker scores. Here we describe the use of a set of 11 rose microsatellite markers to generate a database of molecular profiles of Hybrid Tea varieties. The data were analysed with respect to reproducibility, discriminative power, genetic (sub) structure, and correlation between molecular and DUS characteristics. The use of the markers in the DUS context is discussed with respect to the options 2 and 3 as they were formulated by the UPOV-BMT working group. It is concluded that an option 3 approach (granting of PBR based on distinctness observed with molecular markers) is feasible for ros

Phylogenetic relationships in Betula (Betulaceae) based on AFLP markers

The genus Betula comprises various species in boreal and temperate climate zones of the Northern Hemisphere. The taxonomy of Betula is controversial and complicated by parallel evolution of morphological traits, polyploidization events, and extensive hybridization and introgression among species. Multilocus molecular data from AFLPs were used to provide phylogenetic information. A large number of polymorphic markers (321 variable bands) were produced in 107 Betula accessions from 23 species and 11 hybrids. The AFLP results were largely congruent with the results from previously examined nuclear DNA markers. Four distinct subgenera were identified within the genus Betula. These subgenera were partly in disagreement with the traditional (but disputed) division of the genus. In addition, the results indicated several groups of conspecific taxa. The majority of the species fell within subgenus Betula and shared a high degree of similarity with B. pendula. All hybrids were associated with this group, and the AFLP data contained signals on putative parents for some of the interspecific hybrids. Subgenus Chamaebetula and part of the Neurobetula species should be merged with Betula. The subgenera Betulenta, Betulaster, and the remaining part of Neurobetula are distinct and well supported. Although our results indicate that four major taxonomic groups can be recognized within the genus Betula, the relationship between them remains unclear. This may be due to the occurrence of hybridization and introgression, which would have a homogenizing effect on the relationships between species. Naturally occurring Betula species of hybrid origin may explain the low bootstrap values within the Betula clade

'Ui is een puzzel met 150 duizend stukjes'

Om zeer grote genomen in kaart te kunnen brengen, moeten eerst fundamentele vragen worden opgelost. Zonder hulp van de overheid komen die antwoord er niet, zegt René Smulders. Terwijl grondige sequencing veredeling aantoonbaar versnelt

Monitoring ecologische effectiviteit van verbindingszones; een inventarisatie ten behoeve van een integraal monitoringsprogramma voor provinciale en robuuste verbindingen

In Nederland wordt als onderdeel van de ecologische hoofdstructuur (EHS) een groot aantal verbindingszones aangelegd. Verbindingszones hebben tot doel om de uitwisseling van doelsoorten tussen natuurgebieden te stimuleren en dragen daarmee bij aan de ruimtelijke samenhang van de natuur in Nederland. In deze studie worden, op basis van gesprekken en een literatuur review, de verschillende mogelijkheden vergeleken voor monitoring van het ecologisch functioneren van verbindingszones. Er wordt daarbij onderscheid gemaakt tussen tijdelijke monitoring van de (provinciale) ecologische verbindingszones en structurele monitoring van robuuste verbindingen als onderdeel van de EHS. Er wordt gepleit voor een gecoördineerd monitoringsprogramma gericht op samenwerking tussen rijk, provincies en terreinbeheerders, zowel wat betreft gegevensverzameling als analysemethoden. Het voorstel voor een gecoördineerd monitoringsprogramma omvat een combinatie van een breed in te zetten algemene methode waarbij de aanwezigheid van doelsoorten wordt vastgesteld, en een langdurige monitoring van de daadwerkelijke uitwisseling van doelsoorten in een beperkt aantal verbindingen

In search of genetic diversity in Rosa foetida Hermann in Iran

Rosa foetida is a dense, erect shrub with bright yellow or scarlet flowers with a yellowish reverse petal. It is most abundant in South West Asia. In Iran R. foetida occurs mainly in the mountainous North and West regions. The species is the origin of the strong yellow color in hybrid roses, which was introduced into modern cultivars in 1900 through a single species hybridization event. In this study we have used 10 microsatellite markers to determine diversity in Rosa foetida accessions collected across Iran. To our surprise, nearly all samples collected were of the same genotype, even when collected at different sites. Only four different genotypes have been detected in total. The results are discussed in relation to breeding system, human influence and overall gene pool statu

Natural hybridization between Populus nigra L. and P. x canadensis Moench. Hybrid offspring competes for niches along the Rhine river in the Netherlands

Black poplar (Populus nigra L.) is a major species for European riparian forests but its abundance has decreased over the decades due to human influences. For restoration of floodplain woodlands, the remaining black poplar stands may act as source population. A potential problem is that P. nigra and Populus deltoides have contributed to many interspecific hybrids, which have been planted in large numbers. As these Populus x canadensis clones have the possibility to intercross with wild P. nigra trees, their offspring could establish themselves along European rivers. In this study, we have sampled 44 poplar seedlings and young trees that occurred spontaneously along the Rhine river and its tributaries in the Netherlands. Along these rivers, only a few native P. nigra L. populations exist in combination with many planted cultivated P. x canadensis trees. By comparison to reference material from P. nigra, P. deltoides and P. x canadensis, species-specific AFLP bands and microsatellite alleles indicated that nearly half of the sampled trees were not pure P. nigra but progeny of natural hybridisation that had colonised the Rhine river banks. The posterior probability method as implemented in NewHybrids using microsatellite data was the superior method in establishing the most likely parentage. The results of this study indicate that offspring of hybrid cultivated poplars compete for the same ecological niche as native black poplars

Crop volunteers and climate change; Effects of future climate change on the occurrence of maize, sugar beet and potato volunteers in the Netherlands

COGEM has commissioned a research project on the effect of the possible future climate change on the occurrence of volunteers. One of the aspects that is considered in the risk assessment of GM crops is whether this crop is able to survive and/or establish in the Netherlands. Climate change could possibly facilitate the survival of a conventional or GM crop. This research project was carried out to investigate whether the survival of maize, potato and sugar beet could change as a result of future climate change in order to allow a timely adjustment of COGEM’s advices if needed