
PAA annual awards honor research excellence
The Potato Association of America held its annual meeting July 21-25 in Portland, Oregon. In 2000, an endowment was established to honor the late Frank L. Haynes, longtime professor of potato breeding and genetics at North Carolina State University.
For the past 23 years, the PAA has honored graduate students with cash awards for outstanding student research presentations.
This year’s winners:
Emma Terris (first place)
Bio: I am currently pursuing a Ph.D. in Entomology at the University of Wisconsin-Madison, with a joint M.S. in Agroecology and Entomology as well as Bachelor of Science degree in Genetics and Genomics, and Spanish from the University of Wisconsin-Madison.
Research: Insect pest control continues to be a crucial avenue of research as pests threaten food security, sustainable agricultural practices, and on-farm economics. The evolution of metabolic resistance to insecticides is problematic, considering the destructive capabilities of the most prominent commercial potato pest, the Colorado potato beetle, Leptinotarsa decemlineata (CPB). This beetle can be a devastating pest and is well known for its rapid, adaptive evolution to resist entire classes of insecticides, through various phenotypic and genetic changes.
In this project, dose-response bioassays were used to characterize the extent of cross-resistance to a novel insecticide, and genetic testing was used to examine the molecular response. CPB populations from across the United States were exposed to serial doses of a neonicotinoid, imidacloprid (AdmirePro), as well as a novel and currently unregistered compound, isocycloseram (Plinazolin). Both compounds act on specific nervous system sites, however, isocycloseram represents a new mode of action (IRAC Group 30) and an associated target site to which most, if not all CPB populations were expected to be highly susceptible. However, while CPB across all sampled populations showed greater resistance to imidacloprid than isocycloseram, there was also notable levels of resistance in every population to this new and unused compound.
Further examination of the underlying genetic mechanisms of CPB resistance through amplicon sequencing of RNA compared the differential expression of target site and metabolic detoxification genes between the different active ingredients, each of which were tested across all CPB populations. The results convey that expression of gene families involved in metabolic detoxification may be acting upon both active ingredients (imidacloprid and isocycloseram), underpinning potential cross-resistance to the novel insecticide, which is threatening to the future of effective pest management. These findings implicate the expected performance of new chemical control strategies in the field, as well as help further untangle the expression of gene families involved in metabolic detoxification in CPB.
Sapphire Coronejo (second place)
Bio: I am a second-year Ph.D. student in the Applied Plant Sciences program at the University of Minnesota. I earned my bachelor’s degree in Biology at the University of the Philippines Los Baños.
Research: Potatoes are a vital global food crop, but their complex autotetraploid genome presents challenges in genomic studies, particularly in accurately assessing genetic diversity. With four sets of chromosomes, potatoes often display confusing genetic variation, as duplicated genes (paralogues) can be mistaken for true alleles, complicating genetic analysis.
To simplify this, we used dihaploids, which are plants with two chromosome sets derived from tetraploid mothers, allowing us to apply diploid sequencing technology. We generated a diversity panel from 60 tetraploid mother plants across three market classes (chips, russets, and reds), sequencing the dihaploids to a depth of ~20X using Illumina technology.
Our findings revealed extensive genetic diversity, initially appearing as high allelic variation, with up to 200 alleles and an average of 27 alleles per locus. However, further investigation showed much of this diversity stemmed from paralogous sequences rather than true alleles. By refining our analysis to a more conservative gene set, we identified a smaller range of genetic diversity, highlighting the importance of precise differentiation between allelic and paralogous variations.
Observed heterozygosity ranged from 0.46% to 0.69%, and nucleotide diversity from 0.53% to 0.98%, but in the conservative gene set, heterozygosity significantly increased 16.36%-26.43%, while nucleotide diversity dropped. Additionally, we uncovered patterns of copy number variation, offering insights into the structural dynamics of the potato genome.
Our study underscores the need for refined analytical methods in polyploid crops, advancing both our understanding of potato genetics and providing new tools for improving breeding efforts.
Jake Meeuwsen (third place)
Bio: I am a Ph.D. candidate at Washington State University in the Department of Horticulture. I received my bachelor’s degree in Crop Science from University of Idaho 2022.
Research: My research aims to understand intelligent water- and land-use management practices. Potato growers can improve crop water-use efficiency by altering plant spatial arrangements and populations. Ideal plant spatial arrangements and populations will reduce evaporation via rapid canopy development and improved duration while optimizing the water-use to grower return ratio. As water becomes more of a scarcity, potato growers will likely lose yield and money; however, adjustments in plant populations and spatial arrangement may minimize losses by optimizing crop water productivity. Irrigation research is lacking and is needed to keep growers profitable during dry years.
To provide growers solutions, field trials will be conducted during 2023 to 2025 using two potato cultivars (Clearwater Russet and Ranger Russet) planted into six spatial arrangements (two row widths (32 and 34 in.) x four in-row spacings (6, 9, 12, and 15 in.) and irrigated with four season-long, Evapotranspiration (ET) replacement rates: 60%, 80%, 100%, and 120%. Plant populations range from 12,299 to 32,670 plants/A. Irrigation treatments are implemented following full plant emergence. ET is measured and predicted using soil moisture and environmental data. ET efficacy is analyzed based on spatial arrangement data to determine if ET is adequate for all populations or if ET needs to be altered based on the growers desired planting population. First year data indicates that indeed, growers should reduce plant population if faced with significant water shortages and that the efficacy of modeled ET is dependent on spatial arrangement and plant population.
My project also entails looking at innovative ways to reduce evaporation during irrigation by using a mobile drip system attached to center pivots. Three different mobile drip irrigation rates (60%, 80%, and 100% of ET) are compared to conventional overhead irrigation to determine the potential water savings of mobile drip irrigation.
The results of this study will impact growers and processors because they will apply directly to regional growing conditions which are threatened by climate change and water shortages. Processors will benefit from this research, as well as their customers, through improved post-harvest quality by growers who have the ability to tailor their management practices during these water stress events.
Daphne Crum (fourth place)
Bio: I am a research assistant and a second-year Ph.D. student in Molecular Plant Sciences at Washington State University. I completed a bachelor’s degree in genetics and genomics from UC Davis in 2023.
Project: A two-year study was conducted to compare the field performance, storability, and French fry quality of 12 russet-type potato varieties commonly used by the industry today. Potatoes were grown in both Othello, Washington, and Parma, Idaho each year to compare overall variety performance. Field management of each location followed local recommendations for long-season, russet-type potatoes.
Agronomic performance was determined by assessing the total yield (tons/acre), marketable yield (U.S. No. 1’s & U.S. No. 2’s), tuber counts and size distribution, specific gravity, and relative market value of each variety. Postharvest performance focused on fry color at harvest and after 60-days of storage at 4°C or 9°C. Photovolt reflectance values (stem-end) were measured to assess fry color differences between varieties. Reported USDA color designations for individual French fry planks were estimated using regression analysis from the photovolt reflectance values (0-4; lightest to darkest, respectively). Generally, when tubers are exposed to significant cold (<9°C), some potatoes show susceptibility to “low-temperature sweetening” (LTS), the over-accumulation of reducing sugars associated with darker colored fries following cooking via the Maillard reaction. Increased fry darkening risks finished product deviating from consumer expectations for appearance, taste, and quality, and increases the risk of acrylamide production which has negative health implications for the consumer. Largely, the industry accepts fries that are lighter than a USDA 2 (USDA 0-2), and varieties with tubers stored ≤4ºC, and score lighter than a USDA 1 after frying have been identified by the Washington State University Postharvest program as exhibiting LTS resistance. This trait can improve storability and fry color quality, increase dormancy length, and reduce shrinkage in well managed storages.
The results of this study indicate significant differences between growing location for field performance. The top three yielding varieties coming out of WA and ID out-produced Russet Burbank by 48% and 11%, respectively. Interestingly, the top three yielding varieties from each state were not the same (WA: Alturas, Umatilla Russet, Caribou Russet; ID: Alturas, Dakota Russet, Ranger Russet), and WA produced 27.2% higher total yields than ID across all 12 varieties. Considering storage performance and french fry quality, both states produced acceptably light fries at harvest (USDA 0-2) and when stored at 9°C for all 12 varieties. No variety stored at 4ºC showed evidence of LTS resistance based on our parameters, but Alturas, Clearwater Russet, and Umatilla Russet produced the lightest fries out of colder storage independent of the growth location. Considering all factors of performance in this study, Alturas demonstrated the highest financial value while Russet Burbank exhibited the lowest. It is recommended that field and storage management practices be individually tailored to optimize variety quality given this study was conducted using a single management practice for all 12 varieties. Additionally, it will be valuable to capitalize on varieties exhibiting LTS resistance and other beneficial traits which can improve postharvest performance without jeopardizing quality.
Shengwei Hu (fifth place)
Bio: I am a current Ph.D. student in the Department of Crop and Soil Science, College of Agricultural Sciences, Oregon State University. I earned my master’s degree of Crop Science at OSU, master’s degree of Agribusiness in University of Florida, and my bachelor’s degree of Agronomy at Huazhong Agricultural University.
Research: In the Pacific Northwest, potato production is significantly threatened by soil-borne pathogens such as the Columbia root-knot nematode (CRKN), which can cause direct yield losses by rendering potato tubers unmarketable. The primary method for controlling CRKN involves fumigation prior to planting. However, continuous reliance on fumigation comes with substantial economic and environmental costs. My research focuses on improving soil health by advancing our understanding of CRKN biology, developing diagnostic markers to differentiate between races of the pathogen, and generating enhanced potato germplasm resistant to CRKN.
In the PNW, CRKN is represented by two distinct races, Race 1 and Race 2, along with a pathotype of Race 1, known as Race 1Roza. These races are typically identified through differential host testing. During my master’s research, I sequenced and assembled the most contiguous genome sequences for these CRKN populations, performed gene annotation, and conducted comparative genomic analyses. As a result, I developed diagnostic PCR-based markers capable of efficiently distinguishing between the various races and pathotypes of CRKN. These diagnostic tools are instrumental in managing CRKN by facilitating crop rotation strategies tailored to the host range of each pathotype.
One particular challenge is posed by Race 1Roza, which has overcome resistance from the S. bulbocastanum clone SB22, currently the main source of resistance germplasm. This underscores the urgent need to introgress new sources of resistance against Race 1Roza. Our team has identified four clones from Solanum hougasii (6x) that exhibit high levels of resistance to three CRKN isolates. These resistant clones were used to develop offspring with potential new sources of resistance to CRKN Race 1Roza.
Femi Omilani (Best poster)
Bio: I am Femi Omilani, a Ph.D. candidate in the department of horticulture being co-advised by Dr. Sagar Sathuvalli and Dr. Kelly Vining at Oregon State University. I earned a Master of Agriculture in Plant Breeding and Genetics from the Federal University of Agriculture, Abeokuta, Nigeria (2015), and a Bachelor of Agriculture, specializing in Crop Production and Soil Management, from Bowen University, Iwo, Nigeria (2010).
Research: Columbia Root Knot Nematode (CRKN) is an economically important pest of potato which reduces the commercial value of infected potato tubers. Potato growers spend tens of millions of dollars annually in management costs. Fumigation has proven effective for the management of CRKN, but it is expensive and not environmentally sustainable. Breeding for pest and disease resistance is a viable alternative. Wild species like the Solanum bulbocastanum, a relative of the cultivated potato (S. tuberosum), are an invaluable resource for the introduction of novel traits in breeding efforts. Researchers at the USDA-ARS, Prosser, Washington, developed a CRKN-resistant potato clone – designated as PA99N82-4 – using a wild potato selection – SB22 – as the source of resistance. The plant genome is like a cookbook; it contains instructions that support the plant’s survival in its environment. We sought to discover the whole genome-level similarities (or differences) as well as shared gene(s) or regions(s) which might confer resistance to the CRKN. We used a suite of bioinformatics tools, which are like a digital toolbox, to compare these two complex ‘cookbooks’ (genomes). To do this, we assembled the genome of PA99N82-4 and compared it to an existing genome of SB22 available in the Sathuvalli Lab. Our results showed a high level of similarity between the PA99N82-4 and SB22. Our efforts also culminated in the identification of a gene, shared between the CRKN-resistant pair of PA99N82-4 and SB22, which may be the source of CRKN-resistance. This exciting finding holds promise for the OSU breeding program in its efforts towards developing improved CRKN-resistant potatoes.