1a. Objectives (from AD-416):
The long-term objective of this project is to provide wheat, barley, and sorghum producers with new pest resistant crops and technologies that will protect their crops from insect pests. Specifically, during the next five years we will focus on the following objectives. Objective 1: Identify new sources of resistance to aphids and other insects in wheat, barley, sorghum, and related species. Subobjective 1A. Evaluate available germplasm resources (national germplasm collections and accessible exotic resources) to identify new sources resistant to insect pests [Russian wheat aphid (RWA), greenbug (GB), and bird cherry-oat aphid (BCOA)] in wheat, barley, sorghum, and related species. Subobjective 1B. Define a visual rating scale for use in greenhouse screening of wheat and barley seedlings for identification of BCOA resistance. Subobjective 1C. Determine the field resistance of barley lines which exhibit a unique visual plant response to RWA feeding as seedlings in the greenhouse which is not clearly assigned to a resistance level by Webster's scale of 1 - 9. Objective 2: Characterize the mechanisms and genetics of new sources of aphid resistance in wheat, barley, and sorghum. Subobjective 2.A. Develop and evaluate genetic populations to determine the genetic control of host resistance to GB, RWA, and BCOA in barley. Subobjective 2.B. Develop and evaluate genetic populations to determine levels of genetic diversity of host resistance to GB, RWA, and BCOA in wheat, barley, and sorghum. Subobjective 2.C. Develop and identify molecular markers to facilitate identification of resistance QTLs and cloning of the resistance gene(s), and to aid selection of breeding lines through marker-assisted selection. Subobjective 2.D. Conduct functional genomics studies on host response to GB attack, leading to advanced understanding of the defense mechanisms in the hosts and discovery of genes and factors that affect host defense against insect pests (i.e., GB) in sorghum and related species. Objective 3: Develop improved germplasm of wheat, barley, and sorghum incorporating new sources of insect resistance and other desired traits into elite, adapted backgrounds for the United States. Subobjective 3.A. Develop high performance wheat, barley, and sorghum germplasm with enhanced resistance to GB, RWA, or BCOA, and release to the public. Subobjective 3.B. Develop genetically improved barley and sorghum cultivars and hybrids for use as feedstocks for bioethanol, animal feed, and forage-grazing potential under expanded growth conditions.
1b. Approach (from AD-416):
The long-term goal of this project is to provide wheat, barley, and sorghum producers with new pest resistant crops and technologies that will protect their crops from insect pests. To accomplish the research objectives, the project will search available germplasm collections to find new, effective sources of resistance to virulent aphid pests, including Russian wheat aphid (RWA), greenbug (GB), and bird cherry-oat aphid (BCOA). The genetic diversity and genetic control of resistance in these crops will be characterized using genetic and genomic approaches, leading to advanced understanding of the defense mechanisms in the hosts and discovery of genes and factors that regulate host defense against insect pests. The identified resistance genes will be transferred into elite, adapted genetic backgrounds. Plant genotyping will be conducted to map aphid resistance genes to the crop chromosomes and to develop molecular markers for marker-assisted selection to facilitate the breeding process. The research team of the project will work closely with collaborating plant breeding programs to obtain elite breeding lines to use as parents in backcrossing procedures to transfer aphid resistance and other value-added (e.g., enhanced ethanol production) traits. The genetically improved germplasm will be field-tested for agronomic and quality performance prior to release. The project will provide testing and selecting support to assure these desirable genes move through the various breeding programs on their way to the producers via cultivar and hybrid releases.
3. Progress Report:
This is a new project 6217-21000-008-00D (3/1/13 – 2/28/18). Additional details regarding this research can be found in the annual report for 6217-21000-007-00D, which expired on 2/28/13. Studies of genetic control of greenbug resistance in sorghum: Crosses were made and genetic populations developed to determine genetic diversity in 5 sources of greenbug (GB)-resistant sorghum lines. These included traditional genetic populations and mapping populations. Mapping greenbug resistance genes in sorghum: New markers, SSR and gene-specific markers, were developed to shorten the distance between DNA markers and the QTLs linked to the GB resistance. Analysis of potential candidate genes in the chromosomal location is underway. Developing RWA/GB-resistant winter hulless barley: In an ongoing project to develop Russian wheat aphid (RWA)/GB-resistant winter hulless feed barley varieties for the Southern Plains, evaluated 99 lines in a replicated yield trial at one location. Evaluated 3,600 plant rows in the field, and selected lines for yield trial evaluation in 2014. Selected 100 heads from each of 76 populations. Progeny testing of bird cherry-oat aphid-resistant lines to develop pure lines for further study. Field evaluation in a cooperative study with CSU to determine the economic injury level for five RWA-resistant lines with varying levels of seedling resistance. Made crosses to develop genetic populations that would allow for the determination of genetic diversity for resistance to GB in barley. Completed a cooperative study to determine differential response of eight potentially new sources of resistance in barley to 14 GB biotypes/isolates. Evaluation of a breeding population of wheat: We have selected about 800 F5 lines from progeny of a cross designed to combine RWA resistance, GB resistance, and high yield, OK03825-5403-6/OK05511//OK05212. We plan to evaluate their resistance to GB and RWA in greenhouses, and yield potential in the field in FY2014.