Beurteilung der Fruchtqualität beim Apfel im Rahmen des EU-Projekts Hidras

The EU project Hidras (High Quality Disease Resistant Apples for a sustainable agriculture, QLK5-CT-2002-01-01492) aims to identify genetic factors controlling apple fruit quality with the objective of increasing the acceptability of disease resistant apples. At Agroscope Changins-Wädenswil (ACW) we are performing ex-pert panel tests and consumer tests. The consumer inquiry during the public fair BEA 2005, end of April 2005 in Bern, Switzerland, resulted in comprehensive information on consumption trends in apple for dif-ferent age groups. This work is coordinated with partners in Poland and Belgium. All the age groups consid-ered flavour, juiciness and firmness as very important quality criteria for apples. The preference of apples to other fruit such as pears, bananas or citrus is more significant with adults and especially elder people. How-ever, apple was the most favourite fruit species for all age classes. Almost one third of the adults prefer an apple to other snacks. On the other hand, children prefer chips and popcorn and only 12% prefer an apple to other snacks. The overall appearance and eating quality of scab resistant varieties (Ariane, Topaz and Goldrush) and non-resistant varieties (Gala, FAW 5878 and La Flamboyante) evaluated by the same consumers con-firmed, that the resistant varieties were competitive in respect to fruit quality with the non-resistant varieties

Modern approaches for breeding high quality apples with durable resistance to scab, powdery mildew and fire blight

New methods to allow for more precise selection of tree and fruit characters in breeding programmes were developed in recent years. Marker-assisted selection (MAS) is common practice in the ACW apple breeding programme at Wädenswil. Genetic markers can reduce the number of plants and the time required for evaluation, thus new varieties become commercially available sooner. How can this molecular selection method reasonably be applied in an apple breeding programme? Application of phenotypic and molecular selection techniques in the ACW apple breeding programme and results are presented

Breeding apples with durable disease resistance

Apple cultivars with high fruit quality, good productivity and durable disease and pest resistance are highly required in ecological Fruit growing. In the past apple breeders mainly used single resistance genes giving good field resistance towards scab and mildew. They originate from wild species such as Malus floribunda 821, M. zumi and M. robusta. However, this type of resistance can be overcome by new pathogen races. Today the main emphasis is on the combination of functional different major resistance genes and the use of quantitative resistance to achieve durability. Molecular markers were developed which particularly permit the detection of major resistance genes. The combined presence of the target resistance genes in a seedling can be determined by marker-assisted selection (MAS). Currently similar markers for loci on the genome which determine quantitative resistance (QTL) are being developed. Benefits and limits of durable disease resistant variety in organic Fruit growing will be discussed

Rust mite resistance in apple assessed by quantitative trait loci analysis

The aim of this study was to assess the genetic basis of rust mite (Aculus schlechtendali) resistance in apple (Malus × domestica). A. schlechtendali infestation of apple trees has increased as a consequence of reduced side effects of modern fungicides on rust mites. An analysis of quantitative trait loci (QTLs) was carried out using linkage map data available for F1 progeny plants of the cultivars ‘Fiesta' × ‘Discovery'. Apple trees representing 160 different genotypes were surveyed for rust mite infestation, each at three different sites in two consecutive years. The distribution of rust mites on the individual apple genotypes was aggregated and significantly affected by apple genotype and site. We identified two QTLs for A. schlechtendali resistance on linkage group 7 of ‘Fiesta'. The AFLP marker E35M42-0146 (20.2cM) and the RAPD marker AE10-400 (45.8cM) were closest positioned to the QTLs and explained between 11.0% and 16.6% of the phenotypic variability. Additionally, putative QTLs on the ‘Discovery' chromosomes 4, 5 and 8 were detected. The SSR marker Hi03a10 identified to be associated to one of the QTLs (AFLP marker E35M42-0146) was traced back in the ‘Fiesta' pedigree to the apple cultivar ‘Wagener'. This marker may facilitate the breeding of resistant apple cultivars by marker assisted selection. Furthermore, the genetic background of rust mite resistance in existing cultivars can be evaluated by testing them for the identified SSR marke

High-resolution genetic map of the Rvi15 ( Vr2 ) apple scab resistance locus

The Rvi15 (Vr2) apple scab resistance locus found in the GMAL 2473 accession has been previously mapped to the top of the Linkage Group 2 (LG2) by analyzing 89 progeny plants of a cross between ‘Idared' and GMAL 2473. A new population of 989 progeny plants, derived from a cross between ‘Golden Delicious' and GMAL 2473, has been analyzed with the two SSR markers CH02c02a and CH02f06, previously found to be associated with Rvi15 (Vr2), and with two published markers derived from NBS sequences (ARGH17 and ARGH37) estimated to map close to the Rvi15 (Vr2) locus. ARGH17 and ARGH37, were found to be the closest markers to the resistance locus, bracketing it within an interval of 1.5cM. The SSRs mapped one on each side of Rvi15 (Vr2). CH02f06 mapped at 2.9cM from ARGH37 while CH02a02a mapped at 1.7 from ARGH17. The position of Rvi15 (Vr2) respect to CH02a02a indicates that Rvi15 (Vr2) and Rvi4 (Vh4), a second apple scab gene mapped on the top of LG2, are two different resistance genes. In order to develop even more tightly linked markers to Rvi15 (Vr2), ARGH17 was used as the starting point for chromosome walking through the Rvi15 (Vr2) homolog region of the cv. ‘Florina'. A single ‘Florina' BAC clone, 36I17, was sufficient to span the homologous locus in the new population's recombinant progeny. Sequencing of the 36I17 BAC clone allowed identifying seven putative ORFs, including two showing a TIR-NBS-LRR structure. Ten additional markers could be developed mapping within a 1.8cM interval around the Rvi15 (Vr2) resistance gene. ARGH17 and GmTNL1 markers, the latter also derived from NBS-LRR resistance gene homolog sequence, are the closest markers to Rvi15 (Vr2) bracketing it within a 0.5cM interval. The availability of 12 markers within the Rvi15 (Vr2) region, all within a small physical distance (kbp) in ‘Florina', suggests that cloning of the Rvi15 (Vr2) apple scab resistance gene from GMAL 2473 will be possibl

Züchtung krankheitsresistenter Apfelsorten

Breeding high quality apples combined with excellent agronomic features promotes sustainable production systems. This approach includes durable genetic disease resistance against scab (Venturia inaequalis), powdery mildew (Podosphaera leucotricha) and fire blight (Erwinia amylovora). Glasshouse screening of advanced selections and traditional cultivars with a shoot inoculation test for fire blight resistance highlighted considerable differences. We report on approaches for breeding new high quality scab and mildew resistant and fire blight tolerant varieties including markerassisted selection (MAS) and on promising advanced selections

A candidate gene for fire blight resistance in Malus × robusta 5 is coding for a CC-NBS-LRR

Fire blight is the most important bacterial disease in apple (Malus ×  domestica) and pear (Pyrus communis) production. Today, the causal bacterium Erwinia amylovora is present in many apple- and pear-growing areas. We investigated the natural resistance of the wild apple Malus ×  robusta 5 against E. amylovora, previously mapped to linkage group 3. With a fine-mapping approach on a population of 2,133 individuals followed by phenotyping of the recombinants from the region of interest, we developed flanking markers useful for marker-assisted selection. Open reading frames were predicted on the sequence of a BAC spanning the resistance locus. One open reading frame coded for a protein belonging to the NBS-LRR family. The in silico investigation of the structure of the candidate resistance gene against fire blight of M. ×  robusta 5, FB_MR5, led us hypothesize the presence of a coiled-coil region followed by an NBS and an LRR-like structure with the consensus ‘LxxLx[IL]xxCxxLxxL'. The function of FB_MR5 was predicted in agreement with the decoy/guard model, that FB_MR5 monitors the transcribed RIN4_MR5, a homolog of RIN4 of Arabidopsis thaliana that could interact with the previously described effector AvrRpt2EA of E. amylovor

Snapshots of mean ocean temperature over the last 700 000 years using noble gases in the EPICA Dome C ice core

Together with the latent heat stored in glacial ice sheets, the ocean heat uptake carries the lion’s share of glacial–interglacial changes in the planetary heat content, but little direct information on the global mean ocean temperature (MOT) is available to constrain the ocean temperature response to glacial–interglacial climate perturbations. Using ratios of noble gases and molecular nitrogen trapped in the Antarctic EPICA Dome C ice core, we are able to reconstruct MOT for peak glacial and interglacial conditions during the last 700 000 years and explore the differences between these extrema. To this end, we have to correct the noble gas ratios for gas transport effects in the firn column and gas loss fractionation processes of the samples after ice core retrieval using the full elemental matrix of N2, Ar, Kr, and Xe in the ice and their individual isotopic ratios. The reconstructed MOT in peak glacials is consistently about 3.3+-0.4°C cooler compared to the Holocene. Lukewarm interglacials before the Mid-Brunhes Event 450 kyr ago are characterized by 1.6+-0.4°C lower MOT than the Holocene; thus, glacial–interglacial amplitudes were only about 50%of those after the Mid-Brunhes Event, in line with the reduced radiative forcing by lower greenhouse gas concentrations and their Earth system feedbacks. Moreover, we find significantly increased MOTs at the onset of Marine Isotope Stage 5.5 and 9.3, which are coeval with CO2 and CH4 overshoots at that time.We link these CO2 and CH4 overshoots to a resumption of the Atlantic Meridional Overturning Circulation, which is also the starting point of the release of heat previously accumulated in the ocean during times of reduced overturning

A candidate gene for fire blight resistance in Malus × robusta 5 is coding for a CC-NBS-LRR

Erworben im Rahmen der Schweizer Nationallizenzen (http://www.nationallizenzen.ch)Fire blight is the most important bacterial disease in apple (Malus ×  domestica) and pear (Pyrus communis) production. Today, the causal bacterium Erwinia amylovora is present in many apple- and pear-growing areas. We investigated the natural resistance of the wild apple Malus ×  robusta 5 against E. amylovora, previously mapped to linkage group 3. With a fine-mapping approach on a population of 2,133 individuals followed by phenotyping of the recombinants from the region of interest, we developed flanking markers useful for marker-assisted selection. Open reading frames were predicted on the sequence of a BAC spanning the resistance locus. One open reading frame coded for a protein belonging to the NBS–LRR family. The in silico investigation of the structure of the candidate resistance gene against fire blight of M. ×  robusta 5, FB_MR5, led us hypothesize the presence of a coiled-coil region followed by an NBS and an LRR-like structure with the consensus ‘LxxLx[IL]xxCxxLxxL’. The function of FB_MR5 was predicted in agreement with the decoy/guard model, that FB_MR5 monitors the transcribed RIN4_MR5, a homolog of RIN4 of Arabidopsis thaliana that could interact with the previously described effector AvrRpt2EA of E. amylovora