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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. Here, we report two novel alleles for the MFT‐A and two novel alleles for the MFT‐B1homologs in spring bread wheat and durum wheat. 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 MFTpromote seed dormancy. Variant analysis of the novel MFT‐Aand MFT‐B1alleles 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 MFTthat impact susceptibility to PHS.

The reduced height(Rht‐1) genes in wheat (Triticum aestivumL.) are integral in controlling plant height. Previous studies in other plant species have demonstrated that loss‐of‐function mutations in their orthologous Rht‐1genes 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 D1were combined to create single, double, and triple Rht‐1mutants. Homozygous lines possessing none, one, two, or three Rht‐1stop 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‐1triple 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‐1gene resulted in a normal phenotype. Differences in plant height among the Rht‐1double mutants, Rht‐1single mutants, and Rht‐1all wild‐type dosages trended toward increased plant height with increased Rht‐1stop mutation dosage. Differences in Rht‐1homeolog gene expression did not equate to differences in plant height between the different Rht‐1stop mutations. Nonsense alleles occurring in the GRAS domain of Rht‐A1, B1, and D1were combined to create single, double, and triple Rht‐1mutants.Rht‐1triple mutants exhibited a slender phenotype exhibited by rapid growth, elongated coleoptiles, and internodes.At least one functional copy of a Rht‐1gene was necessary to restore normal plant development.Differences in plant height among the Rht‐1double mutants, Rht‐1single mutants, and Rht‐1all wild‐type dosages trended toward increased plant height with increased Rht‐1 stop mutation dosage.Differences in Rht‐1homeolog gene expression did not equate to differences in plant height between the different Rht‐1stop mutations.

Wheat (Triticumspp.) yield is increased by either producing and testing variants of yield‐limiting genes or crossing to create new allelic combinations. Tiller number and seeds per tiller influence wheat yield, and both are impacted by the Teosinte Branched1(TB1) gene. We screened 16 hard red spring wheat (Triticum aestivumL.) cultivars, 15 hard red winter wheat cultivars and lines, and 10 durum wheat [Triticum turgidumL. subsp. durum(Desf.) van Slageren] cultivars and lines commonly grown in Montana and found several previously reported TB1missense alleles along with one new silent and a missense TB1‐A1allele among the 16 hard red spring wheat cultivars but no TB1null alleles. Among the 10 durum cultivars, five carried a TB1‐B1‐S184Gmissense allele and all winter wheat cultivars carried wild‐type TB1alleles. To determine the impact of TB1null alleles, this study examined durum wheat genotypes varying for TB1null alleles created by ethyl methanesulfonate (EMS) mutagenesis. The goal was to determine the impact of TB1null alleles on tillering, agronomic, and seed traits. The impact of TB1null alleles was studied alone and together in field trials. The TB1single‐ and double‐null mutants produced up to 15% more tillers and 18% with positive trends toward increased plant biomass. The results of this research demonstrate that the integration of EMS‐derived TB1null alleles may prove useful in increasing small‐grain tillering to optimize plant biomass and yield under different growing conditions. Teosinte Branched1null alleles increase wheat tillering.Selection for increased tillering can increase wheat biomass.Teosinte Branched1null impact is influenced by the environment.

Increasing the yield of wheat (Triticumspp.) 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. turgidumL. subsp. durum(Desf.) van Slageren] varieties are either standard height, wild type for Rht(Rht‐B1a), or are semidwarf and carry the Rht‐B1ballele. Rht‐B1bincreases 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 Rhtalleles 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 Rhtmutation upon binding to Gibberellin Insensitive Dwarf1 (GID1). It was found that the Rht‐B1b‐E529Kallele conferred plant height and coleoptile length intermediate between Rht‐B1band Rht‐B1acontaining plants, while two Rht‐A1alleles had lesser impacts with trends toward intermediate‐height plants. The results of this research demonstrate that hypomorphic Rhtalleles that alter Rhtbinding to GID1 may prove useful in optimizing durum wheat height to increase yield across different growing conditions. Rhthypomorphic alleles result in intermediate plant height.Rht‐Ahypomorphic mutations reduce plant height.Intermediate‐height plants carrying hypomorphic Rhtalleles have longer coleoptiles.

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‐8to investigate how each semi‐dwarfing allele impacts gluten composition and flour pasting properties. 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. This study indicates that the Rht‐1semi‐dwarfing alleles increase dough mixing time and tolerance by increasing the relative abundance of high molecular weight glutenins yielding stronger dough. The semi‐dwarfing alleles developed primarily for agronomic purposes have significant impacts on gluten index and starch swelling power.

The introduction of the semidwarfing alleles, Rht‐B1band Rht‐D1b, into wheat (Triticum aestivumL.) varieties significantly increased wheat yields beginning in the 1960s. Despite their agronomic advantage, Rht‐B1band Rht‐D1bare also associated with decreased grain protein content and decreased coleoptile length. Furthermore, there is limited allelic diversity available to wheat breeders beyond Rht‐B1band Rht‐D1b. We identified 16 ethyl methanesulfonate (EMS)‐induced Rht‐1alleles, including a nonsense mutation in each Rht‐1gene: Rht‐A‐Q555stop, Rht‐B‐Q420stop, and Rht‐D‐W559stop. We focused our attention for this study on stop alleles since the Rht‐B1band Rht‐D1balleles also contain premature stop codons. We evaluated the new nonsense alleles by measuring their impact on coleoptile length, gibberellic acid (GA) sensitivity, and DELLA/GID1 interaction. Rht‐A‐Q555stopreduced coleoptile length 16% compared with Rht‐1a(wild type) and repressed coleoptile GA perception similarly to Rht‐B1band Rht‐D1b. Rht‐B‐Q420stopand Rht‐D‐W559stopdid not affect coleoptile length. However, Rht‐B‐Q420stopreduced the ability of germinating seeds to perceive GA, but not as much as Rht‐A555stop, Rht‐B1b, or Rht‐D1b. We also tested whether the novel mutations affected the interaction between DELLA/GID1 in the presence and absence of GA. We found that Rht‐A‐Q555stop, Rht‐B‐Q420stop, and Rht‐D‐W559stopinhibited DELLA/GID1 interaction in the absence of GA, but the interaction was restored in the presence of GA. The identification of Rht‐A‐Q555stop, Rht‐B‐Q420stop, and Rht‐D‐W559stopincreases the allelic diversity of Rht‐1. This study also indicates that the RHT carboxyl terminus is important for DELLA/GID1 interactions.