Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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Item Effects of a barley chromosome 6H grain protein QTL on agronomic traits, malt quality traits, and stomatal control under two irrigation and nitrogen fertilization regimes(Montana State University - Bozeman, College of Agriculture, 2018) Mangel, Dylan J. L.; Chairperson, Graduate Committee: Andreas FischerCereal grain protein concentration (GPC) is an important quality parameter, with high GPC desirable when grain is used for food or feed, while low (typically below 12- 13%) GPC is needed when barley grain is used for malting. A major QTL controlling grain protein has previously been identified on barley chromosome 6H. Based on the comparison with a co-linear region on wheat chromosome 6B, the functional status of a gene coding for a NAC transcription factor (HvNAM-1) is responsible for controlling whole-plant senescence, nutrient remobilization from leaves to developing grains, and grain protein concentration. In this context, the purpose of this study was the analysis of the influence of a low- vs. a high-grain protein allele at this locus on barley agronomic and malting quality parameters in different genetic backgrounds. Integration of the low-protein allele stably lowered GPC by 1.6-1.8%, in both years and across all combinations of genetic backgrounds and management practices. Lines with the low-protein allele matured 1.4 to 2.5 days later, dependent on management, and had stably lower malt protein and diastatic power. Effects on additional agronomic and malt quality parameters including yield, test weight, percentage of plump kernels, free amino nitrogen and alpha-amylase activity were subtler and depended on the genetic background tested. Our data also provide important information on the influence of soil N and water availability on malt quality characteristics. Overall, use of the chromosome 6H low-grain protein allele stably lowered grain and malt protein levels without important negative influences on any of the tested agronomic and malt quality parameters, indicating its usefulness in the development of new malting barley germplasm. The studied chromosome 6H GPC QTL also controls expression of a gene coding for a glycine-rich RNA-binding protein (HvGR-RBP1) that may improve drought tolerance. Stomatal conductance and canopy thermal imaging assays did not show consistent effects of the allelic state of the GPC QTL on stomatal control. However, our data showed important correlations between stomatal conductance, canopy temperature depression and agronomic parameters including yield, demonstrating the value of the performed assays for variety selection and breeding.Item Disease control and plant defense pathways induced by Bacillus mojavensis isolate 203-7 and Bacillus mycoides isolate BmJ(Montana State University - Bozeman, College of Agriculture, 2008) Neher, Oliver Thomas; Chairperson, Graduate Committee: Barry J. Jacobsen.The objective of this study was to investigate the plant defense pathways induced by Bacillus mojavensis isolate 203-7 (203-7) and B. mycoides isolate BmJ (BmJ) and to test their ability to control fungal pathogens on tomato and cucumber by means of systemic acquired resistance (SAR). An Arabidopsis thaliana mutant - Botrytis cinerea pathosystem was used to investigate plant defense pathways activated by 203-7 and BmJ. A. thaliana wild type (Col-0), ein2-1, jar1-1, NahG, ndr1-1/npr1-2, and npr1-1 mutants were induced by application of bacilli, distilled water, or chemical inducers. Both bacilli reduced disease severity on wild type and NahG mutants, but provided no reduction on jar1-1, indicating that induction was salicylic acid (SA) independent but jasmonic acid (JA) dependent. 203-7 induced plants had lower disease severity on npr1-1 and ein1-2 mutants but were equivalent to buffer controls on jar1-1 mutants. BmJ did not decrease disease severity on npr1-1, jar1 or ein2-1 mutants. Enzyme assays confirmed the induction of chitinase, beta-1,3-glucanase, and superoxide dismutase by 203-7 and BmJ. These results demonstrate that induction by 203-7 is JA dependent and NPR1 independent. BmJ is SA independent but NPR1 and JA/ethylene dependent. Bacilli were tested for their ability to control B. cinerea grey mold on hydroponically grown greenhouse tomatoes and Glomerella cingulata var. orbiculare on cucumber by means of SAR. Weekly foliar applications of bacilli were able to significantly (a=0.05) reduce the severity of grey mold leaf lesions and to reduce the area under the disease progress curve (AUDPC) calculated for seven Botrytis stem canker ratings. Chitinase, beta-1,3-glucanase, and SOD activity of apoplastic fluids were not significantly (a=0.05) increased by the treatments. Bacilli reduced total and live spore production of G. orbiculare per mm 2 of lesion and increased beta-1,3-glucanase activity of cucumber apoplastic fluids. Applications of BmJ compared to fungicides for the control of anthracnose in cucumber (var. 'General Lee') and cantaloupe (var. 'Athena') were evaluated in 2004 and 2005 field experiments. BmJ applied seven days before inoculation provided disease reduction in cucumber and cantaloupe statistically equal to the fungicide treatments.