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
Browse
3 results
Search Results
Item Evaluating the impact of Rht hypomorphic mutations in durum wheat(Wiley, 2021-12) Brown, McKenna M.; Martin, John M.; Jobson, Emma M.; Hogg, Andrew C.; Carr, Patrick M.; Giroux, Michael J.Increasing the yield of wheat (Triticum spp.) requires identifying new allelic combinations by crossing or by creating useful variation in yield limiting genes. Wheat yield is impacted by many factors, including tiller number and seeds per tiller, both of which are impacted by the Reduced height (Rht) gene. Durum wheat [T. turgidum L. subsp. durum (Desf.) van Slageren] varieties are either standard height, wild type for Rht (Rht-B1a), or are semidwarf and carry the Rht-B1b allele. Rht-B1b increases productive tillers but can result in plants too short for easy harvest in the northern United States and shorter coleoptiles that reduce dry soil germination. In this study, durum plants varying for Rht alleles created by ethyl methanesulfonate (EMS) mutagenesis were studied to determine the impact of each allele upon agronomic and seed traits. The projects’ goal is to increase durum wheat yield through the development of a plant with height intermediate between current full-height and semidwarf varieties. Experiments included field trials, coleoptile length and gibberellic acid (GA) responsiveness assays, and an in vitro test to determine the impact of each Rht mutation upon binding to Gibberellin Insensitive Dwarf1 (GID1). It was found that the Rht-B1b-E529K allele conferred plant height and coleoptile length intermediate between Rht-B1b and Rht-B1a containing plants, while two Rht-A1 alleles had lesser impacts with trends toward intermediate-height plants. The results of this research demonstrate that hypomorphic Rht alleles that alter Rht binding to GID1 may prove useful in optimizing durum wheat height to increase yield across different growing conditions.Item Rht‐1 semi‐dwarfing alleles increase the abundance of high molecular weight glutenin subunits(Wiley, 2020-11) Jobson, Emma M.; Ohm, Jae-Bom; Martin, John M.; Giroux, Michael J.Background and Objectives Grain protein and starch abundance and composition are quantitative traits that play key roles in wheat quality. The semi-dwarfing alleles of the Reduced height (Rht-1) gene increase tillers and yield but also reduce seed size and protein content. Despite their negative impact on grain protein content, the semi-dwarfing alleles increase dough mixing time and tolerance. This study used near isogenic lines that were either tall or semi-dwarf lines that carried Rht-B1b, Rht-D1b, or Rht-8 to investigate how each semi-dwarfing allele impacts gluten composition and flour pasting properties. Findings None of the semi-dwarfing alleles impacted starch properties. Each reduced flour protein content compared to the tall variety with the largest decreases in Rht-B1b (1.8%) and Rht-D1b (1.5%). The semi-dwarfing lines increased the gluten index (21.5%) compared to Rht-1a. Using SE-HPLC, we determined that the semi-dwarfing lines had an increased relative abundance of high molecular weight glutenins compared to the tall variety. Conclusions This study indicates that the Rht-1 semi-dwarfing alleles increase dough mixing time and tolerance by increasing the relative abundance of high molecular weight glutenins yielding stronger dough. Significance and Novelty The semi-dwarfing alleles developed primarily for agronomic purposes have significant impacts on gluten index and starch swelling power.Item The Impact of the Wheat Rht-B1b Semi-Dwarfing Allele on Photosynthesis and Seed Development Under Field Conditions(2019-02) Jobson, Emma M.; Johnston, Rachel E.; Oiestad, Alanna J.; Martin, John M.; Giroux, Michael J.The Reduced Height (Rht) genes formed the basis for the green revolution in wheat by decreasing plant height and increasing productive tillers. There are two current widely used Rht mutant alleles, Rht-B1b and Rht-D1b. Both reduce plant height by 20% and increase seed yield by 5-10%. They are also associated with decreased seed size and protein content. Here, we tested the degree to which Rht-B1b impacts flag leaf photosynthetic rates and carbon and nitrogen partitioning to the flag leaf and grain during grain fill under field conditions using near isogenic lines (NILs) that were either standard height (Rht-B1a) or semi-dwarf (Rht-B1b). The results demonstrate that at anthesis, Rht-B1b reduces flag leaf photosynthetic rate per unit area by 18% and chlorophyll A content by 23%. Rht-B1b significantly reduced grain protein beginning at 14 days post anthesis (DPA) with the greatest difference seen at 21 DPA (12%). Rht-B1b also significantly decreased individual seed weight beginning at 21 DPA and by 15.2% at 28 DPA. Global expression analysis using RNA extracted from developing leaves and stems demonstrated that genes associated with carbon and nitrogen metabolism are not substantially altered by Rht-B1b. From this study, we conclude that Rht-B1b reduces flag leaf photosynthetic rate at flowering while changes in grain composition begin shortly after anthesis.