Plant Sciences & Plant Pathology
Permanent URI for this communityhttps://scholarworks.montana.edu/handle/1/12
The Department of Plant Sciences and Plant Pathology is part of the College of Agriculture at Montana State University in Bozeman. An exciting feature of this department is the diversity of programs in Plant Biology, Crop Science, Plant Pathology, Horticulture, Mycology, Plant Genetics and Entomology. The department offers BS, MS, and Ph.D. degree program
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Item Wildflower Seed Sales as Incentive for Adopting Flower Strips for Native Bee Conservation: A Cost-Benefit Analysis(2019-07) Delphia, Casey M.; O'Neill, Kevin M.; Burkle, Laura A.Improving pollinator habitat on farmlands is needed to further wild bee conservation and to sustain crop pollination in light of relationships between global declines in pollinators and reductions in floral resources. One management strategy gaining much attention is the use of wildflower strips planted alongside crops to provide supplemental floral resources for pollinators. However, farmer adoption of pollinator-friendly strategies has been minimal, likely due to uncertainty about costs and benefits of providing non-crop flowering plants for bees. Over 3 yr, on four diversified farms in Montana, United States, we estimated the potential economic profit of harvesting and selling wildflower seeds collected from flower strips implemented for wild bee conservation, as an incentive for farmers to adopt this management practice. We compared the potential profitability of selling small retail seed packets versus bulk wholesale seed. Our economic analyses indicated that potential revenue from retail seed sales exceeded the costs associated with establishing and maintaining wildflower strips after the second growing season. A wholesale approach, in contrast, resulted in considerable net economic losses. We provide proof-of-concept that, under retail scenarios, the sale of native wildflower seeds may provide an alternative economic benefit that, to our knowledge, remains unexplored. The retail seed-sales approach could encourage greater farmer adoption of wildflower strips as a pollinator-conservation strategy in agroecosystems. The approach could also fill a need for regionally produced, native wildflower seed for habitat restoration and landscaping aimed at conserving native plants and pollinators.Item Metagenomes from high-temperature chemotrophic systems reveal geochemical controls on microbial community structure and function(2010-03) Inskeep, William P.; Rusch, Douglas B.; Jay, Zackary J.; Herrgard, Markus J.; Kozubal, Mark A.; Richardson, Toby H.; Macur, Richard E.; Hamamura, Natsuko; Jennings, Ryan deM.; Fouke, Bruce W.; Reysenbach, Anna-Louise; Roberto, Frank; Young, Mark J.; Schwartz, Ariel; Boyd, Eric S.; Badger, Jonathan H.; Mathur, Eric J.; Ortmann, Alice C.; Bateson, Mary M.; Geesey, Gill G.; Frazier, MarvinThe Yellowstone caldera contains the most numerous and diverse geothermal systems on Earth, yielding an extensive array of unique high-temperature environments that host a variety of deeply-rooted and understudied Archaea, Bacteria and Eukarya. The combination of extreme temperature and chemical conditions encountered in geothermal environments often results in considerably less microbial diversity than other terrestrial habitats and offers a tremendous opportunity for studying the structure and function of indigenous microbial communities and for establishing linkages between putative metabolisms and element cycling. Metagenome sequence (14–15,000 Sanger reads per site) was obtained for five high-temperature (>65°C) chemotrophic microbial communities sampled from geothermal springs (or pools) in Yellowstone National Park (YNP) that exhibit a wide range in geochemistry including pH, dissolved sulfide, dissolved oxygen and ferrous iron. Metagenome data revealed significant differences in the predominant phyla associated with each of these geochemical environments. Novel members of the Sulfolobales are dominant in low pH environments, while other Crenarchaeota including distantly-related Thermoproteales and Desulfurococcales populations dominate in suboxic sulfidic sediments. Several novel archaeal groups are well represented in an acidic (pH 3) Fe-oxyhydroxide mat, where a higher O2 influx is accompanied with an increase in archaeal diversity. The presence or absence of genes and pathways important in S oxidation-reduction, H2-oxidation, and aerobic respiration (terminal oxidation) provide insight regarding the metabolic strategies of indigenous organisms present in geothermal systems. Multiple-pathway and protein-specific functional analysis of metagenome sequence data corroborated results from phylogenetic analyses and clearly demonstrate major differences in metabolic potential across sites. The distribution of functional genes involved in electron transport is consistent with the hypothesis that geochemical parameters (e.g., pH, sulfide, Fe, O2) control microbial community structure and function in YNP geothermal springs.Item Characterization of resistance to Cephus cinctus Norton (Hymenoptera: Cephidae) in barley germplasm(2018-04) Varella, Andrea C.; Talbert, Luther E.; Achhami, Buddhi B.; Blake, Nancy K.; Hofland, Megan L.; Sherman, Jamie D.; Lamb, Peggy F.; Reddy, Gadi V. P.; Weaver, David K.Most barley cultivars have some degree of resistance to the wheat stem sawfly (WSS), Cephus cinctus Norton (Hymenoptera: Cephidae). Damage caused by WSS is currently observed in fields of barley grown in the Northern Great Plains, but the impact of WSS damage among cultivars due to genetic differences within the barley germplasm is not known. Specifically, little is known about the mechanisms underlying WSS resistance in barley. We characterized WSS resistance in a subset of the spring barley CAP (Coordinated Agricultural Project) germplasm panel containing 193 current and historically important breeding lines from six North American breeding programs. Panel lines were grown in WSS infested fields for two consecutive years. Lines were characterized for stem solidness, stem cutting, WSS infestation (antixenosis), larval mortality (antibiosis), and parasitism (indirect plant defense). Variation in resistance to WSS in barley was compared to observations made for solid-stemmed resistant and hollow-stemmed susceptible wheat lines. Results indicate that both antibiosis and antixenosis are involved in the resistance of barley to the WSS, but antibiosis seems to be more prevalent. Almost all of the barley lines had greater larval mortality than the hollow-stemmed wheat lines, and only a few barley lines had mortality as low as that observed in the solid-stemmed wheat line. Since barley lines lack solid stems, it is apparent that barley has a different form of antibiosis. Our results provide information for use of barley in rotation to control the WSS and may provide a basis for identification of new approaches for improving WSS resistance in wheat.Item A large-scale multiomics analysis of wheat stem solidness and the wheat stem sawfly feeding response, and syntenic associations in barley, Brachypodium, and rice(2018-02) Biyiklioglu, Sezgi; Alptekin, Burcu; Akpinar, B. Ani; Varella, Andrea C.; Hofland, Megan L.; Weaver, David K.; Bothner, Brian; Budak, HikmetThe wheat stem sawfly (WSS), Cephus cinctus Norton (Hymenoptera: Cephidae), is an important pest of wheat and other cereals, threatening the quality and quantity of grain production. WSS larvae feed and develop inside the stem where they are protected from the external environment; therefore, pest management strategies primarily rely on host plant resistance. A major locus on the long arm of wheat chromosome 3B underlies most of the variation in stem solidness; however, the impact of stem solidness on WSS feeding has not been completely characterized. Here, we used a multiomics approach to examine the response to WSS in both solid- and semi-solid-stemmed wheat varieties. The combined transcriptomic, proteomic, and metabolomic data revealed that two important molecular pathways, phenylpropanoid and phosphate pentose, are involved in plant defense against WSS. We also detected a general downregulation of several key defense transcripts, including those encoding secondary metabolites such as DIMBOA, tricetin, and lignin, which suggested that the WSS larva might interfere with plant defense. We comparatively analyzed the stem solidness genomic region known to be associated with WSS tolerance in wild emmer, durum, and bread wheats, and described syntenic regions in the close relatives barley, Brachypodium, and rice. Additionally, microRNAs identified from the same genomic region revealed potential regulatory pathways associated with the WSS response. We propose a model outlining the molecular responses of the WSS-wheat interactions. These findings provide insight into the link between stem solidness and WSS feeding at the molecular level.Item Acute Toxicity of Permethrin, Deltamethrin, and Etofenprox to the Alfalfa Leafcutting Bee(2018-05) Piccolomini, Alyssa M.; Whiten, Shavonn R.; Flenniken, Michelle L.; O'Neill, Kevin M.; Peterson, Robert K. D.Current regulatory requirements for insecticide toxicity to nontarget insects focus on the honey bee, Apis mellifera (L.; Hymenoptera: Apidae), but this species cannot represent all insect pollinator species in terms of response to insecticides. Therefore, we characterized the toxicity of pyrethroid insecticides used for adult mosquito management (permethrin, deltamethrin, and etofenprox) on a nontarget insect, the adult alfalfa leafcutting bee, Megachile rotundata (F.; Hymenoptera: Megachilidae) in two separate studies. In the first study, the doses causing 50 and 90% mortality (LD50 and LD90, respectively) were used as endpoints and 2-d-old adult females were exposed to eight concentrations ranging from 0.0075 to 0.076 μg/bee for permethrin and etofenprox, and 0.0013–0.0075 μg/bee for deltamethrin. For the second study, respiration rates of female M. rotundata were also recorded for 2 h after bees were dosed at the LD50 values to give an indication of stress response. Results indicated a relatively similar LD50 for permethrin and etofenprox, 0.057 and 0.051 μg/bee, respectively, and a more toxic response, 0.0016 μg/bee for deltamethrin. Comparatively, female A. mellifera workers have a LD50 value of 0.024 μg/bee for permethrin and 0.015 μg/bee for etofenprox indicating that female M. rotundata are less susceptible to topical doses of these insecticides, except for deltamethrin, where both A. mellifera and M. rotundata have an identical LD50 of 0.0016 μg/bee. Respiration rates comparing each active ingredient to control groups, as well as rates between each active ingredient, were statistically different (P < 0.0001). The addition of these results to existing information on A. mellifera may provide more insights on how other economically beneficial and nontarget bees respond to pyrethroids.Item Climate Change Perceptions and Observations of Agricultural Stakeholders in the Northern Great Plains(2018-05) Grimberg, Bruna; Ahmed, Selena; Ellis, Colter; Miller, Zachariah J.; Menalled, Fabian D.Communities reliant on subsistence and small-scale production are typically more vulnerable than others to disasters such as earthquakes. We study the earthquakes that struck Nepal in the spring of 2015 to investigate their impacts on smallholder communities and the diverse trajectories of recovery at the household and community levels. We focus on the first year following the earthquakes because this is when households were still devastated, yet beginning to recover and adapt. Through survey questionnaires, focus group discussions, open-ended interviews, and observations at public meetings we analyze physical impacts to farming systems and cropping cycles. We investigate respondent reports of loss and recovery through a new social-ecological recovery assessment instrument and find that diversification of livelihoods and access to common resources, alongside robust community institutions, were critical components of coping and recovery. There was widespread damage to subsistence farming infrastructure, which potentially accelerated ongoing transitions to cash crop adoption. We also find that perceptions of recovery varied widely among and within the typical predictors of recovery, such as caste and farm size, in sometimes unexpected ways. Although postdisaster recovery has material and psychosocial dimensions, our work shows that these may not change in the same direction.Item Competition between cheatgrass and bluebunch wheatgrass is altered by temperature, resource availability, and atmospheric CO2 concentration(2017-12) Larson, Christian D.; Lehnhoff, Erik A.; Noffsinger, Chance; Rew, Lisa J.Global change drivers (elevated atmospheric CO2, rising surface temperatures, and changes in resource availability) have significant consequences for global plant communities. In the northern sagebrush steppe of North America, the invasive annual grass Bromus tectorum (cheatgrass) is expected to benefit from projected warmer and drier conditions, as well as increased CO2 and nutrient availability. In growth chambers, we addressed this expectation using two replacement series experiments designed to test competition between B. tectorum and the native perennial bunchgrass Pseudoroegneria spicata. In the first experiment, we tested the effects of elevated temperature, decreased water and increased nutrient availability, on competition between the two species. In the second, we tested the effects of elevated atmospheric CO2 and decreased water availability on the competitive dynamic. In both experiments, under all conditions, P. spicata suppressed B. tectorum, though, in experiment one, warmer and drier conditions and elevated nutrient availability increased B. tectorum’s competitiveness. In experiment two, when grown in monoculture, both species responded positively to elevated CO2. However, when grown in competition, elevated CO2 increased P. spicata’s suppressive effect, and the combination of dry soil conditions and elevated CO2 enhanced this effect. Our findings demonstrate that B. tectorum competitiveness with P. spicata responds differently to global change drivers; thus, future conditions are unlikely to facilitate B. tectorum invasion into established P. spicata communities of the northern sagebrush steppe. However, disturbance (e.g., fire) to these communities, and the associated increase in soil nutrients, elevates the risk of B. tectorum invasion.Item Effects of an Ultra-low-Volume Application of Etofenprox for Mosquito Management on Megachile rotundata (Hymenoptera: Megachilidae) Larvae and Adults in an Agricultural Setting(2018-02) Piccolomini, Alyssa M.; Flenniken, Michelle L.; O'Neill, Kevin M.; Peterson, Robert K. D.The alfalfa leafcutting bee, Megachile rotundata F. (Hymenoptera: Megachilidae), is one of the most intensively managed solitary bees and greatly contributes to alfalfa production in both the United States and Canada. Although production of certain commodities, especially alfalfa seed, has become increasingly dependent on this species\' pollination proficiency, little information is known about how M. rotundata is affected by insecticide exposure. To better understand the risk posed to M. rotundata by the increasing use of insecticides to manage mosquitoes, we conducted field experiments that directly exposed M. rotundata nests, adults, and larvae to a pyrethroid insecticide via a ground-based ultra-low-volume (ULV) aerosol generator. We directly targeted nest shelters with Zenivex E20 (etofenprox) at a half-maximum rate of 0.0032 kg/ha at dusk and then observed larval mortality, adult mortality, and the total number of completed nests for both the treated and control groups. There was no significant difference in the proportion of dead (P = 0.99) and alive (P = 0.23) larvae when the control group was compared with the treated group. We also did not observe a significant difference in the number of emerged adults reared from the treated shelters (P = 0.22 and 0.50 for females and males, respectively), and the number of completed cells after exposure to the insecticides continued to increase throughout the summer, indicating that provisioning adults were not affected by the insecticide treatment. The results from this study suggest that the amount of insecticide reaching nest shelters may not be sufficient to cause significant mortality.Item Bumble Bees (Hymenoptera: Apidae) of Montana(2017-09) Dolan, Amelia C.; Delphia, Casey M.; O'Neill, Kevin M.; Ivie, Michael A.Montana supports a diverse assemblage of bumble bees (Bombus Latreille) due to its size, landscape diversity, and location at the junction of known geographic ranges of North American species. We compiled the first inventory of Bombus species in Montana, using records from 25 natural history collections and labs engaged in bee research, collected over the past 125 years, as well as specimens collected specifically for this project during the summer of 2015. Over 12,000 records are included, with 28 species of Bombus now confirmed in the state. Based on information from nearby regions, four additional species are predicted to occur in Montana. Of the 28 species, Bombus bimaculatus Cresson and Bombus borealis Kirby are new state records. The presence of B. borealis was previously predicted, but the presence of B. bimaculatus in Montana represents a substantial extension of its previously reported range. Four additional \ eastern\" bumble bee species are recorded from the state, and three species pairs thought to replace one another from the eastern to western United States are now known to be sympatric in Montana. Additionally, our data are consistent with reported declines in populations of Bombus occidentalis Greene and Bombus suckleyi Greene, highlighting a need for targeted surveys of these two species in Montana."Item Characterization of resistance to the wheat stem sawfly in spring wheat landrace accessions from targeted geographic regions of the world(2017-07) Varella, Andrea C.; Weaver, David K.; Cook, Jason P.; Blake, Nancy K.; Hofland, Megan L.; Lamb, Peggy F.; Talbert, Luther E.Plant landraces have long been recognized as potential gene pools for biotic and abiotic stress-related genes. This research used spring wheat landrace accessions to identify new sources of resistance to the wheat stem sawfly (WSS) (Cephus cinctus Norton), an important insect pest of wheat in the northern Great Plains of North America. Screening efforts targeted 1409 accessions from six geographical areas of the world where other species of grain sawflies are endemic or where a high frequency of accessions possesses the resistance characteristic of solid stems. Resistance was observed in approximately 14% of accessions. Half of the lines displayed both antixenosis and antibiosis types of resistance. Among the resistant accessions, 41% had solid or semi-solid stems. Molecular genetic screening for haplotypes at the solid stem QTL, Qss.msub.3BL, showed that 15% of lines shared the haplotype derived from \'S-615\', the original donor of the solid stem trait to North American germplasm. Other haplotypes associated with solid stems were also observed. Haplotype diversity was greater in the center of origin of wheat. Evaluation of a representative set of resistant landrace accessions in replicated field trials at four locations over a three year period identified accessions with potential genes for reduced WSS infestation, increased WSS mortality, and increased indirect defense via parasitoids. Exploitation of distinct types of plant defense will expand the genetic diversity for WSS resistance currently present in elite breeding lines.