PGP

Pear Genomics Research Network

 Most of the U.S. pear genetics researchers and breeders have teamed up under the Pear Genomics Research Network (PGRN), with the objective of working together towards a common goal: the development of new pear cultivars for the U.S. pear industry. The PGRN has the support of the California Pear Advisory Board, the Pear Pest Management Research Fund, the Pear Bureau Northwest and the Washington Tree Fruit Research Commission.

Development of Marker-Based Breeding Technologies for Pear Improvement

Pear production can be increased by developing new varieties with improved agronomic characteristics, such as disease/insect resistances and dwarfing stature, which can be combined with high fruit quality and many other traits. In traditional breeding the selection of such elite cultivars is based on the visual evaluation of phenotype, and in woody perennial crops, including pear, this process is time consuming and expensive, because of the trees’ long juvenile phase, laborious trait assessment, and large land requirement. Marker-assisted selection (MAS) technologies are currently routinely and successfully applied for several plant crops, and they can potentially increase pear breeding efficacy.

We developed an Affymetrix Axiom® Pear 70K Genotyping Array and we used it to screen ~2000 different pear cultivars collected from the National Clonal Germplasm Repository (USDA/ARS NCGR) in Corvallis, OR. These genotypic data will be useful to find strong marker-trait associations to be applied for MAS in pear, information which is currently lacking for most of the traits of interest in this crop.

We are also part of an international consortium (with FEM, IRHS-INRA of Angers and PFR) for the development of a new high-quality reference genome for European pear: ‘Bartlett’ v2.0.

Optimizing a protocol for the high-throughput phenotyping of Armillaria resistance in pear

An issue of growing concern in California pear orchards is the root disease caused by the fungus Armillaria mellea. A. mellea is recalcitrant to soil fumigation and resistant to conventional fungicide applications. Cultural and biological methods can improve yields, but the effect is only temporary. Therefore, the development of Armillaria resistant pear rootstock varieties would be extremely helpful for the control of this disease.

Genetic bases of resistance to Armillaria have never been investigated in pear, and such type of studies are just starting in other fruit and nut crops. Currently, the only phenotyping protocol applicable to large-scale evaluations, such as those necessary for association studies, is an in vitro assay developed for grape. The objective of this project is to test this protocol on a small number of pear rootstock genotypes and evaluate its suitability for high-throughput phenotyping of Armillaria resistance in pear.

Participating Organizations