Height is an important trait related to plant architecture and yield potential in bread wheat (Triticum aestivum L.). We previously identified a major quantitative trait locus QPH.caas-6A flanked by simple sequence repeat markers Xbarc103 and Xwmc256 that reduced height by 8.0–10.4%. Here QPH.caas-6A, designated as Rht24, was confirmed using recombinant inbred lines (RILs) derived from a Jingdong 8/Aikang 58 cross. The target sequences of Xbarc103 and Xwmc256 were used as queries to BLAST against International Wheat Genome Sequence Consortium database and hit a super scaffold of approximately 208 Mb. Based on gene annotation of the scaffold, three gene-specific markers were developed to genotype the RILs, and Rht24 was narrowed to a 1.85 cM interval between TaAP2 and TaFAR. In addition, three single nucleotide polymorphism (SNP) markers linked to Rht24 were identified from SNP chip-based screening in combination with bulked segregant analysis. The allelic efficacy of Rht24 was validated in 242 elite wheat varieties using TaAP2 and TaFAR markers. These showed a significant association between genotypes and plant height. Rht24 reduced plant height by an average of 6.0–7.9 cm across environments and were significantly associated with an increased TGW of 2.0–3.4 g. The findings indicate that Rht24 is a common dwarfing gene in wheat breeding, and TaAP2 and TaFAR can be used for marker-assisted selection.

No abstract

This article is protected by copyright. All rights reserved double mutants OsphyA OsphyB and OsphyA OsphyC flower much earlier than OsphyB and OsphyC single mutants in LD, indicating that OsPHYA contributes to OsPHYB and OsPHYC functions to suppress flowering under LD (Takano et al., 2005). In temperate cereals, PHYB and PHYC have different functions in flowering time from those in Arabidopsis and rice (Section III). CRY2 is the predominant photoreceptor in perception of the LD signal in the control of flowering compared to CRY1 in Arabidopsis (Liu et al., 2011). Likewise, in rice OsCRY2 is a key flowering regulator, while OsCRY1 has little effect on flowering time, suggesting functional conservation of CRYs (Hirose et al., 2006). OsFKF1 also has similar role in flowering time to its counterpart in Arabidopsis (Han et al., 2015). The function of PHOT and UVR8 homologs in rice and temperate grasses remains unknown (Dataset S2). Thus far, no studies have been carried out to investigate the functions of PHYA, CRY and FKF1 homologs in temperate grasses. Temperature sensors Few thermosensors have been identified in plants. Several proteins were reported to integrate temperature information to the clock (Gil & Park, 2019). Strikingly, the plant photoreceptor PHYB can also function as temperature receptors (Jung et al. 2016; Legris et al. 2016). The thermal reversion from active Pfr to the inactive Pr form of PHYB is rapid and can be greatly enhanced by temperature increase between 10 and 30°C. Additionally, PHYB-mediated temperature sensing and temperature-induced alterations in DNA-nucleosome dynamics are supposed to be associated with temperature-mediated entrainment of the clock (Gil & Park, 2019). PHYB function in sensing temperature has not been investigated in rice and temperate grasses. 2. Major components of the circadian clock Progress has been made in determining how the clock functions in Arabidopsis, vastly improving our understanding of its molecular architecture (Creux & Harmer, 2019; Gil & Park, 2019; Sanchez et al., 2020). Many studies show that CIRCADIAN CLOCK ASSOCIATED1 (CCA1), LATE ELONGATED HYPOCOTYL (LHY), PSEUDO-RESPONSE REGULATOR (PRR), GIGANTEA (GI), REVEILLE (RVE), NIGHT LIGHTINDUCIBLE AND CLOCK-REGULATED (LNK), EARLY FLOWERING (ELF) and LUX ARRHYTHMO (LUX) shape the core oscillator of the circadian clock including multiple transcription-translation feedback loops, thus acting as Accepted Article This article is protected by copyright. All rights reserved major components in response to light and temperature cycles (Creux & Harmer, 2019; Sanchez et al., 2020). In the outline of circadian clock, the MYB family genes CCA1 and LHY are induced in the early morning. Subsequently, a second set of MYB family genes, RVE4, RVE6 and RVE8, together with transcriptional coactivators LNK1 and LNK2, are expressed in midday. PRR family genes are also expressed after CCA1 and LHY with a sequential pattern: PRR9, PRR7, PRR5, PRR3, and PRR1 [also known as TIMING OF CAB EXPRESSION 1 (TOC1)]. Finally, a rise in m...

Rht-B1b and Rht-D1b, the 'Green Revolution' (GR) genes, greatly improved yield potential of wheat under nitrogen fertilizer application, but reduced coleoptile length, seedling vigor and grain weight. Thus, mining alternative reduced plant height genes without adverse effects is urgently needed.We isolated the causal gene of Rht24 through map-based cloning and characterized its function using transgenic, physiobiochemical and transcriptome assays. We confirmed genetic effects of the dwarfing allele Rht24b with an association analysis and also traced its origin and distribution.Rht24 encodes a gibberellin (GA) 2-oxidase, TaGA2ox-A9. Rht24b conferred higher expression of TaGA2ox-A9 in stems, leading to a reduction of bioactive GA in stems but an elevation in leaves at the jointing stage. Strikingly, Rht24b reduced plant height, but had no yield penalty; it significantly increased nitrogen use efficiency, photosynthetic rate and the expression of related genes. Evolutionary analysis demonstrated that Rht24b first appeared in wild emmer and was detected in more than half of wild emmer and wheat accessions, suggesting that it underwent both natural and artificial selection.These findings uncover an important genetic resource for wheat breeding and also provide clues for dissecting the regulatory mechanisms underlying GA-mediated morphogenesis and yield formation.

No abstract

High-molecular-weight glutenin subunits (HMW-GS) are major components of seed storage proteins (SSPs) and largely determine the processing properties of wheat (Triticum aestivum) flour. HMW-GS are encoded by the GLU-1 loci and regulated at the transcriptional level by interaction between cis-elements and transcription factors (TFs). We recently validated the function of conserved cis-regulatory modules (CCRMs) in GLU-1 promoters, but their interacting TFs remained uncharacterized. Here we identified a CCRM-binding NAM-ATAF-CUC (NAC) protein, TaNAC100, through yeast one-hybrid (Y1H) library screening. Transactivation assays demonstrated that TaNAC100 could bind to the GLU-1 promoters and repress their transcription activity in tobacco (Nicotiana benthamiana). Overexpression of TaNAC100 in wheat significantly reduced the contents of HMW-GS and other SSPs as well as total seed protein. This was confirmed by transcriptome analyses. Conversely, enhanced expression of TaNAC100 increased seed starch contents and expression of key starch synthesis-related genes, such as TaGBSS1 and TaSUS2. Y1H assays also indicated TaNAC100 binding with the promoters of TaGBSS1 and TaSUS2. These results suggest that TaNAC100 functions as a hub controlling seed protein and starch synthesis. Phenotypic analyses showed that TaNAC100 overexpression repressed plant height, increased heading date, and promoted seed size and thousand kernel weight. We also investigated sequence variations in a panel of cultivars, but did not identify significant association of TaNAC100 haplotypes with agronomic traits. The findings not only uncover a useful gene for wheat breeding but also provide an entry point to reveal the mechanism underlying metabolic balance of seed storage products.

TaVrn1, encoding a MADS-box transcription factor (TF), is the central regulator of wheat vernalization-induced flowering. Considering that the MADS-box TF usually works by forming hetero-or homodimers, we conducted yeast-two-hybrid screening and identified an SVPlike MADS-box protein TaVrt2 interacting with TaVrn1. However, the specific function of TaVrt2 and the biological implication of its interaction with TaVrn1 remained unknown.We validated the function of TaVrt2 and TaVrn1 by wheat transgenic experiments and their interaction through multiple protein-binding assays. Population genetic analysis also was used to display their interplay. Transcriptomic sequencing and chromatin immunoprecipitation assays were performed to identify their common targets.TaVrt2 and TaVrn1 are flowering promoters in the vernalization pathway and interact physically in vitro, in planta and in wheat cells. Additionally, TaVrt2 and TaVrn1 were significantly induced in leaves by vernalization, suggesting their spatio-temporal interaction during vernalization. Genetic analysis indicated that TaVrt2 and TaVrn1 had significant epistatic effects on flowering time. Furthermore, native TaVrn1 was up-regulated significantly in TaVrn1-OE (overexpression) and TaVrt2-OE lines. Moreover, TaVrt2 could bind with TaVrn1 promoter directly.A TaVrt2-mediated positive feedback loop of TaVrn1 during vernalization was proposed, providing additional understanding on the regulatory mechanism underlying vernalizationinduced flowering.

No abstract