WUR Plant Breeding
WUR Plant Breeding
De Klerk G.-J.M.,WUR Plant Breeding |
Van Den Dries N.,WUR Plant Breeding |
Krens F.A.,WUR Plant Breeding
Acta Horticulturae | Year: 2017
The apoplast consists of the cell wall continuum and the intercellular spaces. Flooding of the apoplast is the major causative factor of the hyperhydricity (HH) syndrome. Flooding reduces gas exchange by cells. This leads to anaerobiosis and to accumulation within cells of gases like ethylene. The flooding is caused by the ample availability of water in tissue culture and occurs more on liquid medium and Gelritesolidified medium than on agar-solidified medium. Gelrite causes more HH since medium solidified with Gelrite liquefies, probably because of chelating compounds excreted by plant tissues. Root pressure causes translocation of water from the roots to the apoplast. At the same time, the water that has entered the apoplast cannot easily be removed in vitro by transpiration due to the very high relative humidity in the headspace. When the stomata are forced to close by addition of salicylic acid, transpiration is even more impaired. This results in an increase of HH.
Groeneveld R.A.,Wageningen University |
Ansink E.,VU University Amsterdam |
van de Wiel C.C.M.,WUR Plant Breeding |
Wesseler J.,TU Munich
Sustainability | Year: 2011
In this paper we assess the benefits and costs of introducing biologically contained genetically modified (GM) crops, with an application to the potential introduction of GM tomatoes and eggplants in Italy and Spain. Such crops possess both the standard beneficial GM traits, and they prevent introgression of transgenes from GM crops to their conventional or wild relatives, thereby adding to the safety of their cultivation. As a result, coexistence regulations for these crops are less stringent than for crops without biological containment. The potential adoption of biologically contained GM tomatoes and eggplants is assessed in a cost-benefit framework for Italy and Spain. We conclude that biological containment has considerable potential benefits if policy makers are willing to loosen the restrictions on the introduction of these varieties. © 2011 by the authors.
Koning-Boucoiran C.F.S.,WUR Plant Breeding |
Smulders M.J.M.,WUR Plant Breeding |
Krens F.A.,WUR Plant Breeding |
Esselink G.D.,WUR Plant Breeding |
Maliepaard C.,WUR Plant Breeding
Acta Horticulturae | Year: 2012
Genetic analysis in tetraploid rose is complex: inheritance of genes could be disomic, keeping the two original diploid genomes separate but it could also be tetrasomic, permitting the four homologous chromosomes to pair and recombine during meiosis, and including the possibility of double reduction. Marker-assisted breeding (MAB) is particularly suited for traits such as disease resistance since disease resistance assays are laborious, time and money consuming, but we need to extend the number of markers for better coverage of the genome before being able to find associations and apply MAB. Our goal was to produce hundreds of single nucleotide polymorphism (SNP) markers to provide the coverage needed. Disease resistance, more specifically powdery mildew resistance is our primary target because chemical pest control will be increasingly limited. Molecular markers could provide a good tool to facilitate selection in an earlier stage of a breeding program. We investigated the inheritance of powdery mildew resistance in an F1 population originating from a cross between two tetraploid genotypes, P540 and P867, differing in powdery mildew resistance. SNP marker development started with Next Generation Sequencing (Illumina GAII) of cDNA obtained from RNA isolated from flowers at three developmental stages for each parent. We identified a large number of putative single nucleotide polymorphisms (SNPs) between and within both parents. SNPs that were expected to segregate as simplex × nulliplex and duplex × nulliplex markers were selected for genotyping the entire F1 population using the KASP platform (KBioscience). For a pilot study on a limited number of SNPs we defined specific selection criteria resulting in a set of 20 SNPs for testing on the population. It was found that selecting the SNPs according to the ratio of the number of reads from the Illumina sequencing data did not guarantee the appropriate segregation ratios in the progeny. Continued research will focus on identifying haplotypes and on QTL mapping of powdery mildew resistance. We will present results on the criteria used to select SNP markers, success rate, the realised segregation ratios in the offspring, the reconstruction of the homologous chromosomes (haplotypes) in the cross, and QTL mapping of powdery mildew resistance.