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Comparisons of introduced exotics that invade and those that do not can yield important insights into the ecology of invasions. Centaurea solstitialis, calcitrapa, and sulphurea are closely related, share a similar life history and were each introduced to western North America from Southern Europe ~ 100-200 years ago. However, of these three species, only solstitialis has become invasive. We collected seeds from different populations for each of the three species both in the native range of Spain and the non-native range of California, measured individual seed mass, and grew plants from these seeds in a greenhouse experiment in Montana. The invasive solstitialis had the smallest seeds and seedlings of the three congeners. However, in contrast to its noninvasive congeners, solstitialis had the highest relative growth rates when grown in competition. C. solstitialis was also the only species to show significant differences in traits between populations from different ranges, with plants from the non-native range of California demonstrating greater competitive resistance, larger seed size, and larger seedling mass than plants from the native range in Spain. This suggests that C. solstitialis may be evolving toward larger seed and seedling sizes in this non-native range. Relative growth rate showed no inter-regional variation for any species, but was higher for C. solstitialis than its congeners when in competition, and thus may interact with the evolution of larger seeds and plant mass in ways that contribute to the extraordinary invasive success of this species.

This study investigated the potential of different wheat varieties to influence the performance of the subsequent wheat crop. In fall 2021, a single variety of winter wheat (cv. Norwest Tandem) was planted into standing wheat stubble in plots that were previously planted to five winter wheat varieties. At harvest, yield was significantly affected by the variety that had been planted in each plot during the first year of the trial. Specifically, wheat following the variety Pritchett yielded approximately 12% more than wheat following the variety Bobtail. While planting the second crop, residue from the winter wheat variety Norwest Duet caused the no‐till plot drill to plug (accumulate large amounts of soil and crop residue in front of openers) far more than residue from the other varieties. This indicates that varieties differ in their residue management requirements. These differences could be exploited to best fit different agricultural practices. This study highlights the potential importance of varietal effects that persist in the field after the field is harvested. However, more work is needed to understand varietal differences in residue management requirements and varietal effects of the successive crop before they can be fully leveraged in wheat breeding and genetics, wheat agronomy, variety testing programs, and eventually the producer's field. Core Ideas Wheat variety differences can effect post‐harvest residue mangement requirements. Wheat variety differences can affect the yield of the following crops. More work is needed to understand the mechanisms of these post‐harvest effects.

The Genome-Wide Association Studies approach was used to detect Quantitative Trait Loci associated with tocochromanol concentrations using a panel of 1,466 barley accessions. All major tocochromanol types- α-, β-, δ-, γ-tocopherol and tocotrienol- were assayed. We found 13 single nucleotide polymorphisms associated with the concentration of one or more of these tocochromanol forms in barley, seven of which were within 2 cM of sequences homologous to cloned genes associated with tocochromanol production in barley and/or other plants. These associations confirmed a prior report based on bi-parental QTL mapping. This knowledge will aid future efforts to better understand the role of tocochromanols in barley, with specific reference to abiotic stress resistance. It will also be useful in developing barley varieties with higher tocochromanol concentrations, although at current recommended daily consumption amounts, barley would not be an effective sole source of vitamin E. However, it could be an important contributor in the context of whole grains in a balanced diet.

Fusarium crown rot (FCR) of winter wheat (Triticum aestivum L.), caused by Fusarium pseudograminearm and Fusarium culmorum, is a yield‐limiting disease in arid wheat‐producing areas of the inland Pacific Northwest. Foliar fungicide applications and currently available seed treatments do not control FCR. Alternative crops that provide a rotational benefit to reduce disease are not economically feasible. Major‐gene resistance is unavailable, but there is preliminary evidence that some wheat and barley (Hordeum vulgare L.) cultivars are more resistant than others. We followed up on preliminary work by growing 14 varieties of winter wheat, planted with in‐furrow FCR inoculum, in 2018 and 2019 in Morrow County, Oregon—one of the world's driest wheat producing regions. Two barley cultivars were added to the experiment during the second year of research. Evaluations of cultivar resistance were made by conducting aboveground visual assessments by counting whiteheads, prematurely senesced wheat heads that are indicative of FCR infection. Whitehead count information was correlated with yield and grain volume weight data. Maximum whitehead counts were measured in plots of the FCR‐susceptible check cultivar ‘Stephens’. There was no evidence of a cultivar‐specific relationship between whitehead count and corresponding values for yield and grain volume weight. There was limited evidence that some cultivars have the capacity to compensate for effects of disease. Core Ideas There is evidence that some wheat cultivars have the capacity to compensate for Fusarium crown rot (FCR). It is necessary to corroborate whitehead counts with FCR symptomology on crown tissue. The contradiction of whitehead count data and yield may be due to increased tillering capacity.

Congeneric species with the same native and non-native ranges, but exhibiting different invasiveness, provide opportunities to assess the relative importance of factors contributing to successful invasions. For example, comparing the competitive ability of such congeners against other species from the native and non-native regions of invasive species can provide insight into the role of evolutionary experience with different competitors. We selected two congeneric Centaurea species with overlapping native and non-native ranges but with strikingly different invasive success, Centaurea solstitialis and C. calcitrapa, and conducted experiments with populations from each region using a suite of different native grass species from each region. When grown with Spanish grass species, competitive responses were 32% stronger for C. calcitrapa and 30% stronger for C. solstitialis, than when in competition with grasses native to California. Centaurea solstitialis from California had 66% higher competitive effects on grasses, all species considered together, than Spanish C. solstitialis; whereas the competitive effects of C. calcitrapa on grasses were not significantly different between C. calcitrapa ranges. Our results are consistent with the prediction that the evolution of increased competitive ability (EICA) might contribute to the devastating success of C. solstitialis in California, and that its absence might contribute to the modest naturalization of the non-invasive C. calcitrapa. Escape from the strong competitive effects and responses of grasses from Spain may also contribute to invasive success in California. Our results suggest that studies of EICA should be based on competitive tests, since biomass alone is not always a good predictor of competitive ability.

Classic evolutionary theory suggests that mutations associated with antimicrobial and pesticide resistance result in a fitness cost in the absence of the selective antimicrobial agent or pesticide. There is experimental evidence to support fitness costs associated with resistance to anti-microbial compounds and pesticides across many biological disciplines, including human pathology, entomology, plant sciences, and plant pathology. However, researchers have also found examples of neutral and increased fitness associated with resistance, where the effect of a given resistance mutation depends on environmental and biological factors. We used Zymoseptoria tritici, a model evolutionary plant pathogenic fungus, to compare the competitive ability of fungicide-resistant isolates to fungicide-sensitive isolates. We conducted four large-scale inoculated winter wheat experiments at Oregon State University agriculture experiment stations. We found a significant change in the frequency of fungicide resistance over time in all four experiments. The direction and magnitude of these changes, however, differed by experimental location, year of experiment, and inoculum resistance treatment (fungicide-resistant, resistant/sensitive mixture, and fungicide-sensitive). These results suggest that the competitive ability of resistant isolates relative to sensitive isolates varied depending upon environmental conditions, including the initial frequency of resistant individuals in the population.

Recent advances in genetic technologies have given researchers the ability to characterize genetic marker data for large germplasm collections. While some studies are able to capitalize on entire germplasm collections, others, especially those that focus on traits that are difficult to phenotype, instead focus on a subset of the collection. Typically, subsets are selected using phenotypic or geographic data. One major hurdle in identifying favorable subsets is selecting a criterion that can be used to quantify the value of a subset. This study compares two such criteria, polymorphism information content, and a new criterion based on kinship matrices, which will be called the mean of transformed kinships. These criteria were explored in terms of their ability to select subsets that are favorable for genome wide association studies, and in their ability to select subsets that contain a high number of rare phenotypes. Using phenotypic and genotypic data that has been amassed from the USDA Barley Core Collection, evidence was found to support the hypotheses that subsets based on the mean of transformed kinships were well-suited to select subsets intended for genome-wide association studies, but the same was not found for polymorphism information content. Inversely, evidence was found to support the hypothesis that subsets based on polymorphism information content were well-suited to select subsets intended for rare-phenotype discovery, but the same was not found for subsets selected using the mean of transformed kinships criterion. Tools to select subsets using these two criteria have been released in the R package “GeneticSubsetter.”

Meloidogyne chitwoodi (Columbia root-knot nematode, CRKN) can cause serious damage in potato production systems, decreasing tuber value in the fresh market and processing industries. Genetic resistance to CRKN was first identified from the wild diploid potato species Solanum bulbocastanum accession SB22 and was successfully introgressed into tetraploid potato breeding material. To expand the base of genetic resistance, 40 plant accessions representing nine wild potato species were screened for their resistance to M. chitwoodi. Greenhouse screening identified fifteen clones from S. hougasii, one clone from S. bulbocastanum, and one clone from S. stenophyllidium with moderate to high levels of resistance against three isolates of M. chitwoodi. Geographical mapping showed that the resistance sources identified in this and previous studies primarily originated in the states of Jalisco and Michoacán in west-central Mexico. These new sources of resistance will be introgressed into elite potato populations to facilitate the development of potato cultivars with durable resistance to M. chitwoodi.

The Genome-Wide Association Studies approach was used to detect Quantitative Trait Loci associated with tocochromanol concentrations using a panel of 1,466 barley accessions. All major tocochromanol types- alpha -, beta -, delta -, gamma -tocopherol and tocotrienol- were assayed. We found 13 single nucleotide polymorphisms associated with the concentration of one or more of these tocochromanol forms in barley, seven of which were within 2 cM of sequences homologous to cloned genes associated with tocochromanol production in barley and/or other plants. These associations confirmed a prior report based on bi-parental QTL mapping. This knowledge will aid future efforts to better understand the role of tocochromanols in barley, with specific reference to abiotic stress resistance. It will also be useful in developing barley varieties with higher tocochromanol concentrations, although at current recommended daily consumption amounts, barley would not be an effective sole source of vitamin E. However, it could be an important contributor in the context of whole grains in a balanced diet.