Location: Grain Legume Genetics Physiology Research
2022 Annual Report
Objectives
Objective 1: Determine yield response and identify yield limiting factors of edible legume germplasm when grown under abiotic stress and managed using different production systems.
Sub-objective 1A: Assess inoculant effects on winter survivability, root rhizobial biodiversity, nitrogen fixing capacities, and yield of direct-seeded advanced edible winter pea (Pisum sativum L.) cultivars in a winter wheat crop rotation.
Sub-objective 1B: Identify novel pea germplasm with cold and drought tolerance, in the presence or absence of Rhizobium, to improve food-grade winter pea production across different agro-ecological environments.
Objective 2: Enhance G x E x M to develop biotic stress-resilient edible legume cropping systems that improve sustainable production.
Sub-objective 2A: Assess the G x E x M interactions of multiple bean genotypes to white mold under different tillage, fertilization and irrigation practices.
Sub-objective 2B: Identify and determine Fusarium root rot genetic resistance and the effect of seed treatments on root rot severity, rhizobial formation and winter survival in winter pea under different agro-ecological environments.
Approach
Sub-objective 1A:
Hypothesis: Winter peas will interact favorably with Rhizobium inoculants to improve winter survival, seed nutritional qualities, yield, and soil health.
Approach: Ten food-grade, cold tolerant, winter peas will be grown at two locations. Presence of Rhizobium inoculant on emergence, root nodulation, chlorophyll content, plant height, root/shoot dry weight, root disease severity, rhizobial diversity, soil nitrogen, seed composition, and seed yield/quality over multiple years will be evaluated.
Sub-objective 1B:
Goal: Identify novel pea germplasm from worldwide collections useful for improving cold and drought tolerance in food-grade winter pea cultivars.
Approach: Pea lines evaluated will be screened for cold tolerance (CT) under natural conditions. Lines with CT will be evaluated for drought and disease tolerance in seven rainfall zones. The five highest yielding lines with the best cold and drought tolerance across rainfall zones will be grown at the three lowest rainfall zones and presence/absence of Rhizobium inoculant on these lines evaluated.
Sub-objective 2A:
Goal: Identify G x E x M interactions that improve control of white mold disease of bean.
Approach: Three tillage (conventional, minimum, and no-till) treatments will be evaluated in alternating strips across a field. Two irrigation treatments, 80 and 100 percent evapotranspiration, will be imposed at flowering through maturity. Eight lines will be assessed across tillage x irrigation combinations. Traits measured will include: emergence, stand vigor, flowering date, canopy porosity, lodging, canopy height, normalized difference vegetation index, canopy coverage, canopy temperature, disease incidence/severity, above ground biomass, yield, and seed weight.
Sub-objective 2B:
Goal: Identify genetic resistance and fungicidal seed treatment combinations effective against Fusarium root rot (FRR) species impacting winter pea across different precipitation zones.
Approach: Twelve winter pea fields from six precipitation zones in Washington will be assessed for FRR at four growth stages and species identified. Pea lines from the Pisum Core Collection and cold-tolerant lines identified in Sub-objective 1B will be screened for resistance to the two major FRR species and association and bi-parental mapping populations used to determine quantitative trait loci associated with the resistance. Four winter pea lines with the best CT, resistance to FRR, and yield will be planted in three precipitation zones in Washington and treated with four fungicidal seed treatments to determine best management practices for FRR.
Progress Report
In support of Sub-objective 1A, research trials to determine the effect of a commercial rhizobial inoculant on winter survivability, root rhizobial diversity, nitrogen fixing capacities, and yield of 10 edible winter pea cultivars were planted in 2021 at two sites, Moscow, Idaho, and Lind, Washington. The research trials provided excellent results on winter survivability, nitrogen levels in soils before and after planting, yields and seed protein content associated with inoculated and non-inoculated seed. Plant emergence, foliar frost damage, canopy cover, levels of root nodulation, root disease, plant height and dry shoot weights were measured for all treatments, as well as nodules harvested to characterize the nitrogen-fixing bacteria responsible for the observed nodules. Pea cultivars did not differ in their nodulation rates within each location, but location had a significant effect on the plant nodulation response to inoculation. In the Idaho trial, the native rhizobia were able to form a highly efficient symbiosis with all cultivars based on root nodule appearance and appeared to increase plant height/weight and root rot resistance in colonized roots. Rhizobia and other plant growth promoting bacteria from this symbiotic association were collected and are in the process of genetic analysis. Soil, nodule, and root tissue were also collected for bacterial isolation and microbiome profiling. The 2021 trial in Lind, Washington, was the only trial dramatically impacted by use of a commercial inoculant that promoted nitrogen fixation in plants. Inoculated plants in this trial were more robust than non-inoculated plants. The Lind location had never had peas grown in the crop rotation previously, and this may account for the importance of commercial inoculant since native inoculant was present but likely not at sufficient levels to promote plant growth. In additional research, the nodulation rate of newly released food grade winter pea varieties “USDA-MiCa”, “USDA-Dint”, and “USDA-Klondike” was assessed across four locations in Washington in December 2021 and June 2022. Significant variation in nodulation rates between locations was detected for both Winter and Summer testing, with two locations having no nodulation in December 2021 and low nodulation in June 2022. The soil and plant nodule and root tissue were collected for bacterial isolation and microbiome profiling. DNA isolations from these samples haver nearly been completed.
In support of Sub-objective 1B, pea germplasm with cold and drought tolerance were assessed in different agro-ecological environments. More than 60 lines demonstrating superior cold and drought tolerance, growth vigor and yield were grown in three different agro-ecological sites (Othello, Prosser, and Lind, Washington) in Fall 2021, and we are currently determining yield and hundred seed weight (HSW) of harvested seed. Twelve lines that demonstrated excellent cold tolerance and high vigor (score of 4 or 5 on a scale from 1 to 5, with 5 being the best) were also evaluated at the Lind and Othello sites to determine the effects of commercial seed inoculant on cold tolerance and yield. We observed that application of a rhizobial seed treatment at the Othello and Lind sites did not significantly impact cold tolerance of the lines. The effect of inoculant on yield is currently being determined.
In support of Sub-objective 2A, a field trial that includes two USDA red bean breeding lines and 17 USDA pinto bean breeding lines is being conducted to detect white mold resistance under severe disease pressure induced by excessive irrigation and high nitrogen fertilization. The pinto lines have white mold resistance derived from a diverse multi-parent population. The diversity in sources of resistance genes contributes to the development of lines that express white mold resistance under severe disease pressure.
In support of Sub-objective 2B, in 2022, we evaluated 191 pea lines in repeated greenhouse experiments for resistance to root rot caused by the fungus Fusarium avenaceum. Genetic markers have been identified for these lines and will be used along with the root rot results to identify genetic markers that are highly associated with disease resistance. Once these markers are detected, they can be used to help rapidly identify pea plants with resistance to Fusarium root rot and to isolate genes involved in disease resistance. Additionally, in Fall 2021, we established field experiments at two locations (Lind and Othello, Washington) with five USDA winter pea breeding lines. Lines were treated with five different fungicide seed treatments used to manage Fusarium root rot. We are currently determining if there are significant differences between seed treatments and breeding lines for cold tolerance, emergence, which is an indicator of disease resistance and seed vigor, and yield.
Accomplishments
1. Potential for super-nodulation of winter pea. Legumes form beneficial relationships with soil bacteria (rhizobia) that colonize roots and produce nitrogen fertilizer. Rhizobia-legume symbiosis is a powerful tool for increasing sustainability of legume-cereal crop production systems, however, Fall-sown peas grown in Washington or Idaho have tended to be inefficient at forming beneficial symbiotic relationships with rhiozobia. ARS researchers at Prosser, Washington, identified a field location near Moscow, Idaho, where Fall-sown peas have very efficiently developed beneficial relationships with nitrogen-fixing rhizobia. Plants with better relationships with rhizobia have more shoots and bigger shoots, along with improved disease resistance, than plants with less developed rhizobial relationships. The bacteria isolated from plants with better rhizobial relationships are a valuable source for developing new commercial rhizobia inoculants that will increase sustainability of agricultural production systems across the U.S. Pacific Northwest.
Review Publications
Yurgel, S., Nadeem, M., Cheema, M. 2022. Microbial consortium associated with crustacean shells composting. Microorganisms. 10(5). Article 1033. https://doi.org/10.3390/microorganisms10051033.
Heineck, G.C., Altendorf, K.R., Coyne, C.J., Ma, Y., McGee, R.J., Porter, L.D. 2022. Phenotypic and genetic characterization of the lentil single plant-derived core collection for resistance to root rot caused by Fusarium avenaceum. Phytopathology. 112(9):1979-1987. https://doi.org/10.1094/PHYTO-12-21-0517-R.
Wang, M., Van Vleet, S., McGee, R.J., Paulitz, T.C., Porter, L.D., Schroeder, K., Vandemark, G.J., Chen, W. 2021. Chickpea seed rot and damping-off caused by metalaxyl-resistant Pythium ultimum and its management with ethaboxam. Plant Disease. 105(6):1728-1737. https://doi.org/10.1094/PDIS-08-20-1659-RE.
