Performing Department
Entomology and Plant Pathology
Non Technical Summary
Hard winter wheat production in the Great Plains is challenged by multiple diseases and most importantly stripe rust, leaf rust, Septoria nodorum blotch (SNB), and some viral diseases. Our first objective is to identify disease resistance genes in Great Plains hard winter wheat to leaf rust, stripe rust, and SNB. Mapping resistance genes to these highly damaging diseases will enable the development of molecular markers for use in marker-assisted breeding. Genotyping by sequencing, association mapping, bi-parental population mapping, and competitive allele specific PCR (KASP) markers will be implemented to map and identify rust and SNB resistance genes. The second objective is to develop a high-throughput phenotyping (HTP) pipeline to speed large-scale selection for barley yellow dwarf resistance in breeding programs. Multispectral and hyperspectral cameras attached to unmanned aerial vehicles and statistical modeling will be used to develop a HTP system to enable rapid and unbiased in-field selection for barley yellow dwarf resistance. Our third objective is to identify the occurrence and diversity of viruses infecting wheat in Oklahoma using Electronic-probe Diagnostic Nucleic acid Analysis. Routine surveillance of wheat viruses is essential for informed decisions on cultivar release. Our fourth objective focuses on the integration of research with training of wheat growers, stakeholders, county educators, and students on wheat disease diagnosis and effective disease management strategies. This project collaborates with other public wheat breeding programs in Oklahoma, Kansas, and Washington. This project will contribute to improved wheat production in the US and globally.
Animal Health Component
0%
Research Effort Categories
Basic
50%
Applied
40%
Developmental
10%
Goals / Objectives
Goals:This project focuses on plant breeding discovery and research and is crucial to wheat cultivar development in the US Great Plains and globally to counter the most damaging wheat diseases. This project is expected to provide sources of resistance/susceptibility to leaf rust, stripe rust, and Septoria nodorum blotch (SNB) in contemporary US hard winter wheat, which will benefit plant breeders and growers. We will also dissect the genetic basis of rust resistance and SNB susceptibility and develop molecular markers for use in marker assisted selection (MAS) to facilitate the transfer of resistance sources to future cultivars. Since the used genotypes in this project are from a public breeding program, the knowledge gained will be directly translated into wheat genetic improvement in the U.S and globally. We will mobilize technologies to develop a high throughput phenotyping system for large scale-field selection for barley yellow dwarf resistance. This will speed the development of resistant germplasm to a common vial disease in Oklahoma and the Great Plains. Furthermore, we will identify the occurrence, distribution, and diversity of viruses infecting wheat in Oklahoma fields and develop novel and rapid method for detection and diagnosis of wheat viruses. This should enhance our understanding of regional distributions and prevalence of wheat viruses in Oklahoma and consequently promote informed breeding decisions. Findings from this project will be used to educate and train wheat growers, county educators, and students on wheat disease diagnosis and effective management strategies.Objectives1. Characterize wheat genetic resources for resistance/susceptibility to leaf rust, stripe rust, and Septoria nodorum blotch.2. Develop high-throughput phenotyping system for large-scale selection of barley yellow dwarf resistance in wheat breeding programs.3. Identify the occurrence and diversity of viruses infecting wheat in Oklahoma using E-probe Diagnostic Nucleic Acid Analysis (EDNA).4. Broder impacts: educate and train growers, county educators, and students on wheat disease diagnosis and effective management strategies.
Project Methods
Objective 1. Characterize wheat genetic resources for resistance to leaf rust, stripe rust, and Septoria nodorum blotch 1.1. Genome-wide association mapping to identify rust resistance genes in HWW.Seedling tests: To identify leaf rust seedling resistance genes in a HWW association mapping panel of 586 genotypes, seedling evaluations will be performed, using five U.S. Pt races including that are common in the Great Plains. For stripe rust, preliminary testing found that almost all lines are susceptible to race PSTv-37 and a mixture of Pst isolates from Oklahoma.Adult-plant stage tests: The HWW association mapping panel was planted in fall 2023 in multiple leaf rust and stripe rust nurseries to be evaluated at adult-plant stage in spring 2024. Stripe rust evaluations will be in Oklahoma, Washington, and in Kansas. Leaf rust evaluations will be in OK and KS.Genome-wide association mapping (GWAS) and competitive allele specific PCR (KASP) marker development: GWAS will be performed using the generated phenotypic leaf/stripe rust data and 30,524 SNP markers generated from Genotyping-by-sequencing (GBS). SNPs significantly linked to novel/underutilized genes that have a large effect on rust response will be converted into KASP markers for use in marker-assisted breeding.1.2. Bi-parental population mapping to identify stripe rust adult-plant resistance (APR) genes in wheat cultivars.Three biparental populations were planted in the fall of 2023 for stripe rust evaluations in Oklahoma, Kansas, and Washington to characterize stripe rust APR genes in the wheat cultivars Gallagher, Baker's Ann and Green Hammer. The parent and double haploid (DH) and recombinant inbred lines (RIL) for the three biparental crosses will be evaluated in four stripe rust nurseries in OK, KS, and WA in 2024. The DH and RIL populations and their parents will be genotyped using GBS (Poland et al., 2012). Linkage groups will be generated using R/qtl package (Broman et al., 2003). QTL analysis will then be performed using different methods such as composite interval mapping. KASP markers will be developed for flanking SNP markers of identified genes.1.3. Unravel genetic factors underlying Septoria nodorum blotch (SNB) resistance or susceptibility in hard winter wheat.Seedling evaluations: Three seeds per genotype (586 breeding lines and cultivars + SNB differential lines) will be planted in a randomized complete block design with two replicates. Five previously characterized Oklahoma P. nodorum isolates will be used for seedling evaluations. P. nodorum isolate culturing, inoculum preparation, and inoculation will be as described by Ruud et al. (2019). Seven days after inoculation, plant reactions will be scored 0-to-5 scale as described by Liu et al. (2004). Toxin infiltration assays will also be performed using five characterized effectors SnToxA, SnTox1, SnTox3, SnTox5, and SnTox267 to determine the presence/absence of the corresponding wheat sensitivity genes.Adult-plant stage evaluations: The 586 breeding lines and cultivars will be tested at the OSU Entomology and Plant Pathology farm in Stillwater, OK. The lines will be planted in 1.5 m row plots and in a randomized complete block design with two replicates. Naturally infected straw with P. nodorum will be spread in the field at Zadoks stage 25-29 (Zadoks et al., 1974, prior to stem elongation) to enhance SNB infection. Leaf blotch and glume blotch scorings will be carried as described by Ruud et al. (2019).Genotyping, GWAS, and KASP marker development: The wheat genotypes will be screened for the presence/absence of cloned sensitivity genes Tsn1 and Snn1, as diagnostic markers for these genes are available. To identify other sensitivity/resistance genes in this germplasm. KASP markers for unknown resistance/susceptibility genes or genes that do not have yet diagnostic markers will be developed.Objective 2. Develop high-throughput phenotyping system for large-scale selection of barley yellow dwarf resistance in wheat breeding programs Plant material and BYD visual assessment: We will collect BYD ratings using visual assessment and HTP in 1) Dual purpose observation nursery (DPON) with large plots and 2) OSU elite breeding line nursery for years 2024 and 2025 (single-row plots). Although there will be overlapping genotypes between years, different breeding lines will be tested in each year. BYD scoring will be performed 3-4 times per season using a 0 - 5 scale.High-throughput phenotyping: The HTP data collection dates will be aligned with BYD visual assessment dates. Multispectral imagery using a DJI Phantom 4 Multispectral quadcopter will be used to collect multispectral imagery in the red, green, blue, red edge and near infra-red spectral ranges. Hyperspectral imagery will be collected using a Headwall Hyperspectral Co-Aligned Camera mounted on a DJI Matrice 600 Hexacopter.Modeling: Post-processed HTP imagery will be segmented on a pixel-wise basis into healthy and diseased leaf tissue using Bayesian image analysis (Moores et al., 2020). The problem will be modeled as a Gaussian mixture between the distribution of healthy and diseased leaf tissue. These mixtures will then be converted to the 0-5 rating scale. The mixture model will be trained against visually scored (i.e. non-HTP) phenotypic data and will be evaluated for prediction accuracy using k-fold cross-validation. Additionally, methods based on ordinary differential equation modeling will be developed to assess disease trajectory over time. Accuracy and stability of estimates will be compared across plot types (single row vs. large plot).Objective 3. Identify the occurrence and diversity of viruses infecting wheat in Oklahoma using E-probe Diagnostic Nucleic Acid Analysis (EDNA) Update EDNA-Poaceae: We will design and add to the existing EDNA-Poaceae database, e-probes for nine wheat viruses WSSMV, SBWMV, BYDV-PAV, BYDV-MAV, CYDV-RPV, HPWMoV, TriMV, WSMV, and BMV, allowing for their rapid identification. This updated EDNA-Poaceae with a total of 42 viruses will help detect known wheat viruses and any of the other viruses infecting grasses.Sample collection and diagnosis: Winter wheat samples will be collected from plants showing virus-like symptoms such as chlorosis, mosaic, and stunting. A total of ~ 900 samples will be collected for a period of 3 years in Oklahoma wheat producing counties. EDNA protocol will be as described in previous studies (Stobbe et al., 2013; Espindola et al., 2015). RT-PCR will be used to confirm EDNA diagnostic outputs.Multiplex RT-PCR assay: A multiplex RT-PCR will also be developed to facilitate the detection of economically important wheat viruses that often exist in co-infections and to validate the new updated EDNA-Poaceae. Multiplex RT-PCR will be developed for three groups of viruses 1) HPWMoV, TriMV, BMV, and WSMV, 2) BYDV-PAV, BYDV-MAV, and CYDV-RPV transmitted by cereal aphids, and 3) WSSMV and SBWMV transmitted by Polymyxa graminis.Objective 4. Broder impacts: educate and train growers, county educators, and students on wheat disease diagnosis and effective management strategies: We will provide training and presentations at extension meetings in Oklahoma. We will educate stakeholders and county educators on wheat disease diagnosis and management during field days. OSU wheat variety trials will serve as demonstration plots for variety reactions to different diseases. We will also plan to produce extension videos, newsletters, and factsheets.