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 Novel alleles of MFT‐A and MFT‐B1 appear to impact wheat preharvest sprouting in Triticum aestivum and Triticum turgidum ssp. durum(Wiley, 2024-05) Tillet, Brandon J.; Vetch, Justin M.; Martin, John M.; Giroux, Michael J.Background and Objectives. Preharvest sprouting (PHS) is the premature germination of seeds, which is often caused by late-season rains after seeds reach physiological maturity. PHS negatively impacts grain yield and end-use quality. Previous studies in spring bread wheat (Triticum aestivum) and durum wheat (Triticum turgidum) have identified that some mutations in the mother of FT and TFL1 gene (MFT) coding sequence decrease seed dormancy and increase wheat PHS. Findings. Here, we report two novel alleles for the MFT-A and two novel alleles for the MFT-B1 homologs in spring bread wheat and durum wheat. Conclusions. A haplotype analysis suggests that TaMFT-3A1b (OQ729929), TaMFT-3B1b (OQ729932) and TdMFT-3B1b (OQ729937) increase PHS susceptibility. It is expected that functional copies of MFT promote seed dormancy. Variant analysis of the novel MFT-A and MFT-B1 alleles in both spring and durum wheat suggest impairment of protein function, therefore a negative impact on seed dormancy. Significance and Novelty: Previously unassessed durum wheat varieties were examined for PHS susceptibility. The information in this study can serve as a resource for spring and durum wheat breeders to make selections for alleles of MFT that impact susceptibility to PHS.Item Dosage response to reduced height‐1 (Rht‐1) loss‐of‐function mutations and characterization of slender phenotype in hexaploid wheat(Wiley, 2023-10) Ugrin, Josey M.; Hogg, Andrew C.; Tracy, Emma M.; Tillet, Brandon J.; Cook, Jason P.; Martin, John M.; Giroux, Michael J.The reduced height (Rht-1) genes in wheat (Triticum aestivum L.) are integral in controlling plant height. Previous studies in other plant species have demonstrated that loss-of-function mutations in their orthologous Rht-1 genes results in plants with a slender phenotype illustrated by increased plant heights, sterility, and a constitutive gibberellic acid (GA3) response; however, this phenotype has not been described in wheat. In this study, nonsense alleles occurring in the GRAS domain of Rht-A1, B1, and D1 were combined to create single, double, and triple Rht-1 mutants. Homozygous lines possessing none, one, two, or three Rht-1 stop mutations were grown in replicated field trials in three environments to assess agronomic traits. Germination tests to measure GA3 responsiveness and gene expression analysis via RNA-seq were also performed. Rht-1 triple mutants exhibited a slender phenotype characterized by rapid growth, elongated coleoptiles and internodes, elongated spikes, decreased tiller and spikelet number, and sterile heads. The presence of a single functional Rht-1 gene resulted in a normal phenotype. Differences in plant height among the Rht-1 double mutants, Rht-1 single mutants, and Rht-1 all wild-type dosages trended toward increased plant height with increased Rht-1 stop mutation dosage. Differences in Rht-1 homeolog gene expression did not equate to differences in plant height between the different Rht-1 stop mutations.Item Missense alleles of the HMW glutenin subunits Dx5 and Dy10 have small changes in function relative to missense changes in Puroindoline a and b(Wiley, 2022-12) Martin, John M.; Zhang, Jinrui; Hogg, Andrew C.; Giroux, Michael J.Background and Objectives. The high molecular weight glutenin subunit genes (HMW-GS) in wheat (Triticum aestivum L.) play a key role in determining dough functionality. More specifically allelic variation for the Glu-D1 subunit loci is consistently associated with bread making quality. Since much of the hard wheat germplasm is fixed for the more favorable 1Dx5 + 1Dy10 haplotype, our goal was to identify allelic variation in 1Dx5 and 1Dy10 HMW-GS genes using an ethyl methanesulfonate (EMS) mutagenized population in the soft white spring wheat cultivar “Alpowa.” The same source population was previously used in screening for creating novel alleles in Puroindoline a (Pina) and Puroindoline b (Pinb) which are responsible for grain hardness variation. Direct sequencing of 384 M3 families identified 135 point mutations equally dispersed across 1Dx5 and 1Dy10. The mutation discovery rate was 1/12.7 kb of DNA, equal to that found in the Pin loci. Mutation carrying plants were crossed to the nonmutagenized Alpowa parent to create F2 populations segregating for the induced EMS HMW Glutenin mutations. Swelling index of gluten (SIG) was measured from seed from field grown plants to assess the impact of each EMS mutation upon Glutenin function. Findings. Nonsense mutations in both 1Dx5 and 1Dy10 reduced SIG values, indicating both 1Dx5 and 1Dy10 are needed for gluten functionality. Missense mutations did not alter SIG values compared to their wild type counterparts. In contrast missense mutations within the tryptophan-rich region of both PINS increased grain hardness pointing to the importance of this protein region. No such region in 1Dx5 or 1Dy10 was found indicating these proteins are structurally stable and tolerant of amino acid substitution. Conclusions. Results from the Glu-D1 subunit and Pin loci show that useful phenotypic variation can be created using EMS mutagenesis for genes where naturally occurring mutations occur from amino substitutions as is the case for the Pin loci. Significance and Novelty. EMS induced mutations are useful for creating new alleles in storage proteins with much greater impacts in genes that have a defined active site as for the Pin loci than in genes such as the HMW Glu-1 genes which have a long repetitive region.Item TAMFT‐3A and TAMFT‐3B2 homeologs are associated with wheat preharvest sprouting(Wiley, 2022-08) Vetch, Justin Michael; Tillett, Brandon J.; Bruckner, Phil L.; Martin, John M.; Marlowe, Karol; Hooker, Marcus Alan; See, Deven Robert; Giroux, Michael J.The phenomenon of preharvest sprouting (PHS), caused by rain after physiological maturity and prior to harvest, negatively affects wheat (Triticum aestivum L.) production and end use. Investigating the genetics that control PHS resistance may result in increased control of seed dormancy. Multiple genes involved in the development of seed dormancy are associated with PHS. In this study, the TaMFT (3A, 3B1, 3B2, 3D), TaMKK3-4A, and TaVP1-3B genes were assessed for association with PHS in a double-haploid line (DHL) hard red winter wheat population derived from a BC1 cross between the cultivars Loma and Warhorse, where Loma was the recurrent and PHS susceptible parent. The 162 BC1 DHL lines were grown over two field seasons and PHS susceptibility was assessed by measuring PHS resistance in physiologically mature heads. The PHS variation was associated with the TaMFT-A and the B2 homeolog with Loma carrying mutant forms of each gene. No sequence variation between Loma and Warhorse was detected in the exons of the TaMFT-B1 and D homeologs. No association between PHS resistance and TaMKK3-4A or TaVp1-3B variation was observed, though Loma and Warhorse vary for TaMKK3-4A and TaVp1-3B mutations reported to be PHS associated. Previous research has shown TaMFT-3A as having a large impact on PHS resistance. In the current study, the TaMFT-3A and TaMFT-3B2 alleles each explained 14% of observed PHS variation. Markers for both TaMFT-3A and TaMFT-3B2 should be used in selecting for increased wheat dormancy and PHS resistance.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.