Using SNP arrays to leverage historic data sets for improved prediction accuracy and estimation of GxE of fruit maturity in sweet cherry (abstract)

Publishe

Genetics of zonal leaf chlorosis and genetic linkage to a major gene regulating skin anthocyanin production (MdMYB1) in the apple (Malus × domestica) cultivar Honeycrisp.

'Honeycrisp' is a widely grown and acclaimed apple cultivar that is commonly used in breeding programs. It also has a well-documented tendency to develop the physiological disorder, zonal leaf chlorosis (ZLC). This disorder causes reduced photosynthetic capacity and is thought to be due to a problem with phloem loading, although the underlying genetics of the disorder have not previously been discerned. In order to understand the breeding implications of the disorder, six families with 'Honeycrisp' as a parent and one family with 'Honeycrisp' as both a maternal and paternal grandparent were evaluated for ZLC incidence over two years. One major quantitative trait locus (QTL) for ZLC incidence was identified on linkage group (LG) 9. A haplotype in 'Honeycrisp' that originated from grandparent 'Duchess of Oldenburg' was associated with increased ZLC incidence in offspring in both years and all families evaluated. The LG9 QTL was 5 to 10 cM from MdMYB1, which is a major gene regulating fruit skin anthocyanin production. 'Honeycrisp' is heterozygous for red fruit skin overcolor at MdMYB1. The 'Honeycrisp' haplotype at the LG9 QTL associated with increased ZLC is in linkage phase with the allele at MdMYB1 associated with red color. Selection for the red allele from 'Honeycrisp' at MdMYB1 will result in most offspring also inheriting the haplotype at the LG9 QTL associated with high ZLC. The occurrence of two copies of this haplotype was sub-lethal in seedlings of a family where both parents inherited both the red overcolor allele at MdMYB1 and the haplotype at the LG9 QTL associated with high ZLC. This is the first study to have identified a genetic component of ZLC with clear breeding implications

Light-emitting organic field-effect transistor using an organic heterostructure within the transistor channel

The authors have realized a light-emitting organic field-effect transistor. Excitons are generated at the interface between a n-type and a p-type organic semiconductor heterostructure inside the transistor channel. The dimensions and the position of the p-n heterostructure are defined by photolithography. The p-n heterostructure is at a distance of several microns from the metal electrodes. Therefore, the exciton and photon quenching in this device is reduced. Numerical simulations fit well with the experimental data and show that the light-emitting zone can move within the transistor channel. (c) 2006 American Institute of Physics.status: publishe

Headed apple architecture data year 1 and 2

Phenotypic data of 1-year-old and 2-year-old headed trees from a germplasm collection modern cultivars and older local varietie

Data from: Sylleptic branching in winter-headed apple (Malus × domestica) trees: accession-dependent responses and their relationships with other tree architectural characteristics

Well-feathered apple trees are essential for commercial orchards to optimize yields. However, most cultivars do not form these sylleptic branches readily in commercial nurseries due to high apical dominance. Several treatments exist to promote their formation in the nurseries, one of which is heading. However, not all cultivars are expected to react similarly to these treatments. We studied the branching response of 155 genotypes following heading and its relation to other architectural traits as a function of the cultivar’s genetic background. Trees were grown for two consecutive years after grafting in a nursery, and the main axes were headed in the winter following growth in year 1. After heading, a single shoot was retained when growth resumed in the second year. Plant architectural traits such as growth of the main shoot, internode length, sylleptic branching, etc. were measured before and after heading and were statistically compared using a mixed model. This model showed the effect of heading for all architectural traits studied. In addition significant genotype and genotype × treatment interactions were found. In general, genotypes that showed a more vigorous growth during the first year also reacted more vigorously to heading. Accounting for the genetic substructure of this collection, no clear distinction in tree response could be found except in a small group of individuals that belonged to an F1 mapping population. This study shows that heading is not favorable for all genotypes to promote sufficient sylleptic branching and that other methods are needed to promote branching in these accessions

Sylleptic branching in winter-headed apple (<em>Malus × domestica</em>) trees: accession-dependent responses and their relationships with other tree architectural characteristics

UMR AGAP - équipe AFEF - Architecture et fonctionnement des espèces fruitièresInternational audienceWell-feathered apple trees are essential for commercial orchards to optimize yields. However, most cultivars do not form these sylleptic branches readily in commercial nurseries due to high apical dominance. Several treatments exist to promote their formation in the nurseries, one of which is heading. However, not all cultivars are expected to react similarly to these treatments. We studied the branching response of 155 genotypes following heading and its relation to other architectural traits as a function of the cultivar’s genetic background. Trees were grown for two consecutive years after grafting in a nursery, and the main axes were headed in the winter following growth in year 1. After heading, a single shoot was retained when growth resumed in the second year. Plant architectural traits such as growth of the main shoot, internode length, sylleptic branching, etc. were measured before and after heading and were statistically compared using a mixed model. This model showed the effect of heading for all architectural traits studied. In addition significant genotype and genotype × treatment interactions were found. In general, genotypes that showed a more vigorous growth during the first year also reacted more vigorously to heading. Accounting for the genetic substructure of this collection, no clear distinction in tree response could be found except in a small group of individuals that belonged to an F1 mapping population. This study shows that heading is not favorable for all genotypes to promote sufficient sylleptic branching and that other methods are needed to promote branching in these accessions

As It Stands: The Palouse Wild Cider Apple Breeding Program

Providing hands-on education for the next generation of plant breeders would help maximize effectiveness of future breeding efforts. Such education should include training in introgression of crop wild relative alleles, which can increase genetic diversity while providing cultivar attributes that meet industry and consumer demands in a crop such as cider apple. Incorporation of DNA information in breeding decisions has become more common and is another skill future plant breeders need. The Palouse Wild Cider apple breeding program (PWCabp) was established at Washington State University in early 2014 as a student-run experiential learning opportunity. The objectives of this study were to describe the PWCabp’s approaches, outcomes, and student involvement to date that has relied on a systematic operational structure, utilization of wild relatives, and incorporation of DNA information. Students chose the crop (cider apple) and initial target market and stakeholders (backyard growers and hobbyists of the Palouse region). Twelve target attributes were defined including high phenolics and red flesh. Phase one and two field trials were established. Two promising high-bitterness selections were identified and propagated. By running the PWCabp, more than 20 undergraduate and graduate students gained experience in the decisions and operations of a fruit breeding program. PWCabp activities have produced desirable new germplasm via utilization of highly diverse Malus germplasm and trained new plant breeding professionals via experiential learning

Elucidating the genetic background of the early-flowering transgenic genetic stock T1190 with a high-density SNP array

Apple trees have a long juvenile period, which makes apple genetic improvement via breeding costly and time-consuming. Transgenic genetic stocks carrying the early-flowering gene BpMADS4 have been used to reduce the juvenility of apple from five or more years to less than 10 months. One such genetic stock, T1190, has been used widely in breeding and research. It was reported to be a seedling of ‘Pinova’ but the other parent was unknown. Not knowing the alleles that this unknown parent contributed to T1190 brings uncertainties to breeding programs and research studies. In this study, the full pedigree of the genetic stock T1190 was reconstructed using an apple 20K SNP array and a panel of 530 reference cultivars and breeding selections. T1190 was determined to be an offspring of ‘Pinova’ and ‘Idared’. The full pedigree of T1190 was used to deduce the mosaic ancestor composition of the transgene-hosting chromosome. Such knowledge is useful to ensure breeding programs and research studies achieve their expected objectives.</p