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.

Background and objectives: The introduction of the semi-dwarfing Reduced Height (Rht) genes in wheat led to dramatic yield increases. The two most common forms of the gene, Rht-B1b and Rht-D1b have been widely incorporated into wheat varieties. However, despite their agronomic benefits and prevalence in modern wheat cultivars, much less is known regarding their impact on end-use quality and nutrition. For this study, we compared near-isogenic lines (NILs) carrying either Rht-B1b, Rht-D1b, Rht-8 or no semi-dwarfing alleles. Findings: Our agronomic results agreed with previous studies; we observed a 25% height reduction, 13% yield increase, and a 2% decrease in grain protein content in the semi-dwarf NILs. However, despite the decreased protein content, the Rht-B1b/Rht-D1b NILs had increased bake mixing time (33%), but reduced loaf volume (7%). We also observed that although the semi-dwarfing alleles decreased kernel weight by 15%, they were associated with a 2% increase in flour yield. Flours prepared from the semi-dwarf NILs had decreased Zinc, Iron, and Manganese while having increased levels of Potassium and Calcium. Conclusions: These findings demonstrate that while Rht-B1b/Rht-D1b negatively impact kernel size and protein content they positively impact flour yield and dough mixing strength. Significance and novelty: The most common wheat semi-dwarf alleles decrease kernel size, protein, and micronutrient content while increasing flour yield. K E Y W O R D Sbread making, end-use quality, nutrition, Rht, wheat

SUMMARY Wild relatives of tomato are a valuable source of natural variation in tomato breeding, as many can be hybridized to the cultivated species (Solanum lycopersicum). Several, including Solanum lycopersicoides, have been crossed to S. lycopersicum for the development of ordered introgression lines (ILs), facilitating breeding for desirable traits. Despite the utility of these wild relatives and their associated ILs, few finished genome sequences have been produced to aid genetic and genomic studies. Here we report a chromosome‐scale genome assembly for S. lycopersicoides LA2951, which contains 37 938 predicted protein‐coding genes. With the aid of this genome assembly, we have precisely delimited the boundaries of the S. lycopersicoides introgressions in a set of S. lycopersicum cv. VF36 × LA2951 ILs. We demonstrate the usefulness of the LA2951 genome by identifying several quantitative trait loci for phenolics and carotenoids, including underlying candidate genes, and by investigating the genome organization and immunity‐associated function of the clustered Pto gene family. In addition, syntenic analysis of R2R3MYB genes sheds light on the identity of the Aubergine locus underlying anthocyanin production. The genome sequence and IL map provide valuable resources for studying fruit nutrient/quality traits, pathogen resistance, and environmental stress tolerance. We present a new genome resource for the wild species S. lycopersicoides, which we use to shed light on the Aubergine locus responsible for anthocyanin production. We also provide IL boundary mappings, which facilitated identifying novel carotenoid quantitative trait loci of which one was likely driven by an uncharacterized lycopene β‐cyclase whose function we demonstrate.

The introduction of the semidwarfing alleles, Rht-B1b and Rht-D1b, into wheat (Triticum aestivum L.) varieties significantly increased wheat yields beginning in the 1960s. Despite their agronomic advantage, Rht-B1b and Rht-D1b are also associated with decreased grain protein content and decreased coleoptile length. Furthermore, there is limited allelic diversity available to wheat breeders beyond Rht-B1b and Rht-D1b. We identified 16 ethyl methanesulfonate (EMS)-induced Rht-1 alleles, including a nonsense mutation in each Rht-1 gene: Rht-A-Q555stop, Rht-B-Q420stop, and Rht-D-W559stop. We focused our attention for this study on stop alleles since the Rht-B1b and Rht-D1b alleles 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-Q555stop reduced coleoptile length 16% compared with Rht-1a (wild type) and repressed coleoptile GA perception similarly to Rht-B1b and Rht-D1b. Rht-B-Q420stop and Rht-D-W559stop did not affect coleoptile length. However, Rht-B-Q420stop reduced 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-W559stop inhibited 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-W559stop increases the allelic diversity of Rht-1. This study also indicates that the RHT carboxyl terminus is important for DELLA/GID1 interactions. 1 INTRODUCTION Gibberellic acid (GA) is part of a family of plant hormones that regulate seed germination, stem elongation, leaf expansion, and flower development. They also play a key