Soybean gene for resistance to alphis glycines
Inventors
Hill, Curtis B. • Hartman, Glen L.
Assignees
US Department of Agriculture USDA • University of Illinois System
Publication Number
US-8692053-B2
Publication Date
2014-04-08
Expiration Date
2027-10-09
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Abstract
An Aphis glycines resistance Rag2 gene is provided herein, along with methods for identifying its presence using marker-assisted selection. A cultivar of G. max having resistance to Aphis glycines conferred by the Rag2 gene has been identified. The Rag2 gene, as well as the methods, aphid-resistant varieties, and markers disclosed herein may be used to breed new elite lines expressing soybean aphid resistance.
Core Innovation
An Aphis glycines resistance gene designated Rag2 has been identified in soybean, mapped to a novel chromosomal locus on linkage group F, and is closely linked to molecular markers Soyhsp176 and Satt510. This gene confers strong resistance to the soybean aphid by preventing aphid colonization through reduced aphid multiplication, survival, and development. The resistance expressed by Rag2 is dominant over susceptibility and effective against all known soybean aphid biotypes.
The problem addressed is the significant damage caused by the soybean aphid, Aphis glycines, an invasive pest first found in the U.S. Midwest in 2000 and responsible for substantial yield losses and plant damage. There was, prior to this invention, limited and ineffective integrated pest management for A. glycines, with no known resistance gene in cultivated soybean (Glycine max). Existing soybean aphid resistance genes, Rag1 and related genes, were distinct from Rag2. The invention solves the need for molecular tools and markers to identify and breed soybean varieties with aphid resistance.
The invention further provides methods for identifying the presence or absence of the Rag2 resistance gene in soybean germplasm using marker-assisted selection with linked DNA markers. This enables more efficient breeding of soybean cultivars resistant to Aphis glycines. The methods include introgressing Rag2 into susceptible or less resistant soybean germplasm, producing inbred soybean lines homozygous for Rag2 resistance, and stacking Rag2 with other aphid resistance genes such as Rag1 from linkage group M to maximize resistance durability and effectiveness.
Claims Coverage
The claims include a method with multiple inventive features related to reliably introgressing soybean aphid resistance via the Rag2 gene into soybean germplasm using marker-assisted selection, accompanied by defining the linked genetic locus and markers.
Method for introgressing Rag2 resistance into soybean germplasm
A method comprising crossing a first soybean germplasm having Rag2-conferred Aphis glycines resistance with a second germplasm lacking said resistance or having less resistance, producing progeny, and selecting progeny with Rag2 resistance.
Marker-assisted selection using linked DNA markers
Analyzing progeny germplasm via marker-assisted selection to detect the Rag2 locus on linkage group F, defined as flanked by markers Soyhsp176 and Satt510, by identifying allelic DNA polymorphisms linked to Rag2 resistance and present in PI200538.
Use of specified molecular markers for detection
Selecting molecular markers from the group consisting of Satt510, Soyhsp176, Sat—234, and Sat—297, or other markers mapping within 20 cM of these on linkage group F, for identification of the Rag2 gene by marker-assisted selection.
Compatibility with soybean germplasm having resistance on linkage group M
Applying the method where the second soybean germplasm has resistance to Aphis glycines conferred by another gene located on linkage group M, allowing stacking of resistance genes.
Use of germplasm with agronomic traits
Performing the method with a second germplasm possessing desirable agronomic traits, facilitating introduction of Rag2 without compromising these traits.
Production of inbred cultivar homozygous for Rag2 resistance
Self-crossing plants testing positive for Rag2 resistance until a homozygous inbred line adapted for hybrid combinations conferring Aphis glycines resistance is obtained.
The claims comprehensively cover the method of introgressing Rag2-mediated aphid resistance into soybean lines, defining the Rag2 locus genetically and the use of linked molecular markers for efficient selection, including the stacking of resistance with genes on other linkage groups, and generating homozygous inbred lines adapted for hybrid seed production.
Stated Advantages
Enables efficient and reliable identification of the Rag2 resistance gene in soybean plants using linked molecular markers, obviating the need for direct aphid bioassays.
Facilitates the breeding and development of elite soybean cultivars with durable resistance to soybean aphids through marker-assisted selection and gene stacking.
Reduces time and cost in soybean breeding programs by allowing marker-based selection for aphid resistance rather than relying solely on phenotypic assays with live insects.
Provides strong resistance effective against all known soybean aphid biotypes, including biotypes that overcome prior resistance genes such as Rag1.
Documented Applications
Breeding soybean cultivars resistant to the soybean aphid Aphis glycines by introgressing the Rag2 gene into non-resistant or less resistant soybean germplasm using marker-assisted selection.
Producing inbred soybean lines homozygous for the Rag2 aphid resistance gene adapted for conferring resistance in hybrid combinations.
Stacking Rag2 resistance with other soybean aphid resistance genes located on different linkage groups to enhance resistance durability and spectrum.
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