Plant Sciences & Plant Pathology
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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 Non-target site resistance to flucarbazone, imazamethabenz and pinoxaden is controlled by three linked genes in Avena fatua(2018-02) Burns, Erin E.; Keith, Barbara K.; Talbert, Luther E.; Dyer, William E.Extensive herbicide usage has led to the evolution of resistant weed populations that cause substantial crop yield losses and increase production costs. The multiple herbicide-resistant (MHR) Avena fatua populations utilised in this study are resistant to members of all selective herbicide families, across five modes of action, available for A. fatua control in US small grain production, and thus pose significant agronomic and economic threats. Resistance to acetolactate synthase and acetyl-CoA carboxylase inhibitors is not conferred by known target site mutations, indicating that non-target site resistance (NTSR) mechanisms are involved. Understanding the inheritance of NTS MHR is of upmost importance for continued agricultural productivity in the face of the rapid increase in resistant weed populations worldwide. As few studies have examined the inheritance of NTSR in autogamous weeds, we investigated the inheritance and genetic control of NTSR in the highly autogamous, allohexaploid species A. fatua. We found that NTSR in MHRA. fatua is controlled by three separate, closely-linked nuclear genes for flucarbazone-sodium, imazamethabenz-methyl and pinoxaden. The single-gene NTSR inheritance patterns reported here contrast with other examples in allogamous species and illustrate the diversity of evolutionary responses to strong selection.Item Constitutive redox and phosphoproteome changes in multiple herbicide resistant Avena fatua L. are similar to those of systemic acquired resistance and systemic acquired acclimation(2018-01) Burns, Erin E.; Keith, Barbara K.; Mohammed, Refai Y.; Bothner, Brian; Dyer, William E.Plants are routinely confronted with numerous biotic and abiotic stressors, and in response have evolved highly effective strategies of systemic acquired resistance (SAR) and systemic acquired acclimation (SAA), respectively. A much more evolutionarily recent abiotic stress is the application of herbicides to control weedy plants, and their intensive use has selected for resistant weed populations that cause substantial crop yield losses and increase production costs. Non-target site resistance (NTSR) to herbicides is rapidly increasing worldwide and is associated with alterations in generalized stress defense networks. This work investigated protein post-translational modifications associated with NTSR in multiple herbicide resistant (MHR) Avena fatua, and their commonalities with those of SAR and SAA. We used proteomic, biochemical, and immunological approaches to compare constitutive protein profiles in MHR and herbicide susceptible (HS) A. fatua populations. Phosphoproteome and redox proteome surveys showed that post-translational modifications of proteins with functions in core cellular processes were reduced in MHR plants, while those involved in xenobiotic and stress response, reactive oxygen species detoxification and redox maintenance, heat shock response, and intracellular signaling were elevated in MHR as compared to HS plants. More specifically, MHR plants contained constitutively elevated levels of three protein kinases including the lectin S-receptor-like serine/threonine-protein kinase LecRK2, a well-characterized component of SAR. Analyses of superoxide dismutase enzyme activity and protein levels did not reveal constitutive differences between MHR and HS plants. The overall results support the idea that herbicide stress is perceived similarly to other abiotic stresses, and that A. fatua NTSR shares analogous features with SAR and SAA. We speculate that MHR A. fatua's previous exposure to sublethal herbicide doses, as well as earlier evolution under a diversity of abiotic and biotic stressors, has led to a heightened state of stress preparedness that includes NTSR to a number of unrelated herbicides.Item Proteomic and biochemical assays of glutathione-related proteins in susceptible and multiple herbicide resistant Avena fatua L.(2017-06) Burns, Erin E.; Keith, Barbara K.; Refai, Mohammed Y.; Bothner, Brian; Dyer, William E.Extensive herbicide usage has led to the evolution of resistant weed populations that cause substantial crop yield losses and increase production costs. The multiple herbicide resistant (MHR) Avena fatua L. populations utilized in this study are resistant to members of all selective herbicide families, across five modes of action, available for A. fatua control in U.S. small grain production, and thus pose significant agronomic and economic threats. Resistance to ALS and ACCase inhibitors is not conferred by target site mutations, indicating that non-target site resistance mechanisms are involved. To investigate the potential involvement of glutathione-related enzymes in the MHR phenotype, we used a combination of proteomic, biochemical, and immunological approaches to compare their constitutive activities in herbicide susceptible (HS1 and HS2) and MHR (MHR3 and MHR4) A. fatua plants. Proteomic analysis identified three tau and one phi glutathione S-transferases (GSTs) present at higher levels in MHR compared to HS plants, while immunoassays revealed elevated levels of lambda, phi, and tau GSTs. GST specific activity towards 1-chloro-2,4-dinitrobenzene was 1.2-fold higher in MHR4 than in HS1 plants and 1.3- and 1.2-fold higher in MHR3 than in HS1 and HS2 plants, respectively. However, GST specific activities towards fenoxaprop-P-ethyl and imazamethabenz-methyl were not different between untreated MHR and HS plants. Dehydroascorbate reductase specific activity was 1.4-fold higher in MHR than HS plants. Pretreatment with the GST inhibitor NBD-Cl did not affect MHR sensitivity to fenoxaprop-P-ethyl application, while the herbicide safener and GST inducer mefenpyr reduced the efficacy of low doses of fenoxaprop-P-ethyl on MHR4 but not MHR3 plants. Mefenpyr treatment also partially reduced the efficacy of thiencarbazone-methyl or mesosulfuron-methyl on MHR3 or MHR4 plants, respectively. Overall, the GSTs described here are not directly involved in enhanced rates of fenoxaprop-P-ethyl or imazamethabenz-methyl metabolism in MHR A. fatua. Instead, we propose that the constitutively elevated GST proteins and related enzymes in MHR plants are representative of a larger, more global suite of abiotic stress-related changes.Item Intensive herbicide use has selected for constitutively elevated levels of stress-responsive mRNAs and proteins in multiple herbicide-resistant Avena fatua L.(2017-08) Keith, Barbara K.; Burns, Erin E.; Bothner, Brian; Carey, Charles C.; Mazurie, Aurélien J.; Hilmer, Jonathan K.; Biyiklioglu, Sezgi; Budak, Hikmet; Dyer, William E.BACKGROUND: Intensive use of herbicides has led to the evolution two multiple herbicide-resistant (MHR) Avena fatua (wild oat) populations in Montana that are resistant to members of all selective herbicide families available for A. fatua control in U.S. small grain crops. We used transcriptome and proteome surveys to compare constitutive changes in MHR and herbicide susceptible (HS) plants associated with non-target site resistance (NTSR). RESULTS: Compared to HS plants, MHR plants contained constitutively elevated levels of differentially expressed genes (DEGs) with functions in xenobiotic catabolism, stress response, redox maintenance, and transcriptional regulation that are similar to abiotic-stress tolerant phenotypes. Proteome comparisons identified similarly elevated proteins including biosynthetic and multifunctional enzymes in MHR plants. Of 25 DEGs validated by RT-qPCR assay, differential regulation of 21 co-segregated with flucarbazone-sodium herbicide resistance in F3 families, and a subset of 10 of these were induced or repressed in herbicide-treated HS plants. CONCLUSIONS: Although the individual and collective contributions of these DEGs and proteins to MHR remain to be determined, our results support the idea that intensive herbicide use has selected for MHR populations with altered, constitutively-regulated patterns of gene expression that are similar to those in abiotic stress-tolerant plants. 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