Abstract
Wheat stripe rust, caused by
Puccinia striiformis
f. sp.
tritici
(
Pst
), is a global threat to wheat production.
Aegilops tauschii
, one of the wheat progenitors, carries the
YrAS2388
locus ...for resistance to
Pst
on chromosome 4DS. We reveal that
YrAS2388
encodes a typical nucleotide oligomerization domain-like receptor (NLR). The
Pst
-resistant allele
YrAS2388R
has duplicated 3’ untranslated regions and is characterized by alternative splicing in the nucleotide-binding domain. Mutation of the
YrAS2388R
allele disrupts its resistance to
Pst
in synthetic hexaploid wheat; transgenic plants with
YrAS2388R
show resistance to eleven
Pst
races in common wheat and one race of
P
.
striiformis
f. sp.
hordei
in barley. The
YrAS2388R
allele occurs only in
Ae. tauschii
and the
Ae. tauschii
-derived synthetic wheat; it is absent in 100% (
n
= 461) of common wheat lines tested. The cloning of
YrAS2388R
will facilitate breeding for stripe rust resistance in wheat and other Triticeae species.
Male sterility is a valuable trait for plant breeding and hybrid seed production. The dominant male-sterile gene Ms2 in common wheat has facilitated the release of hundreds of breeding lines and ...cultivars in China. Here, we describe the map-based cloning of the Ms2 gene and show that Ms2 confers male sterility in wheat, barley and Brachypodium. MS2 appears as an orphan gene within the Triticinae and expression of Ms2 in anthers is associated with insertion of a retroelement into the promoter. The cloning of Ms2 has substantial potential to assemble practical pipelines for recurrent selection and hybrid seed production in wheat.
In this study, a numerical analysis was conducted on aluminum alloy reticulated shells (AARSs) with gusset joints under fire conditions. First, a thermal-structural coupled analysis model of AARSs ...considering joint semi-rigidity was proposed and validated against room-temperature and fire tests. The proposed model can also be adopted to analyze the fire response of other reticulated structures with semi-rigid joints. Second, a parametric analysis was conducted based on the numerical model to explore the buckling behavior of K6 AARS with gusset joints under fire conditions. The results indicated that the span, height-to-span ratio, height of the supporting structure, and fire power influence the reduction factor of the buckling capacity of AARSs under fire conditions. In contrast, the reduction factor is independent of the number of element divisions, number of rings, span-to-thickness ratio, and support condition. Subsequently, practical design formulae for predicting the reduction factor of the buckling capacity of K6 AARSs were derived based on numerical analysis results and machine learning techniques to provide a rapid evaluation method. Finally, further numerical analyses were conducted to propose practical design suggestions, including the conditions of ignoring the ultimate bearing capacity analysis of K6 AARS and ignoring the radiative heat flux.
The post-translational import of nuclear-encoded chloroplast preproteins is critical for chloroplast biogenesis, and the Toc159 family of proteins is the receptor for this process. Our previous work ...identified and analyzed the Toc GTPase in tomato; however, the tomato-specific transport substrate for Toc159 is still unknown, which limits the study of the function of the TOC receptor in tomato. In this study, we expand the number of preprotein substrates of slToc159 receptor family members using slToc159-1 and slToc159-2 as bait via a split-ubiquitin yeast two-hybrid membrane system. Forty-one specific substrates were identified in tomato for the first time. Using slToc159-1GM and slToc159-2GM as bait, we compared the affinity of the two bait proteins, with and without the A domain, to the precursor protein, which suggested that the A domain endowed the proproteins with subclass specificity. The presence of the A domain enhanced the interaction intensity of slToc159-1 with the photosynthetic preprotein but decreased the interaction intensity of slToc159-2 with the photosynthetic preprotein. Similarly, the presence of the A domain also altered the affinity of slToc159 to non-photosynthetic preproteins. Bimolecular fluorescence complementation (BiFC) analysis showed that A domain had the ability to recognize the preprotein, and the interaction occurred in the chloroplast. Further, the localization of the A domain in Arabidopsis protoplasts showed that the A domain did not contain chloroplast membrane targeting signals. Our data demonstrate the importance of a highly non-conserved A domain, which endows the slToc159 receptor with specificity for different protein types. However, the domain containing the information on targeting the chloroplast needs further study.
Leaf, spike, stem, and root morphologies are key factors that determine crop growth, development, and productivity. Multiple genes that control these morphological traits have been identified in ...Arabidopsis, rice, maize, and other plant species. However, little is known about the genomic regions and genes associated with morphological traits in wheat. Here, we identified the ethyl methanesulfonate-derived mutant wheat line M133 that displays multiple morphological changes that include upward-curled leaves, paired spikelets, dwarfism, and delayed heading. Using bulked segregant RNA sequencing (BSR-seq) and a high-resolution genetic map, we identified TraesCS1D02G155200 (HB-D2) as a potential candidate gene. HB-D2 encodes a class III homeodomain-leucine zipper (HD-ZIP III) transcription factor, and the mutation was located in the miRNA165/166 complementary site, resulting in a resistant allele designated rHb-D2. The relative expression of rHb2 in the mutant plants was significantly higher (P < 0.01) than in plants homozygous for the WT allele. Independent resistant mutations that disrupt the miRNA165/166 complementary sites in the A- (rHb-A2) and B-genome (rHb-B2) homoeologs showed similar phenotypic alterations, but the relative intensity of the effects was different. Transgenic plants expressing rHb-D2 gene driven by the maize UBIQUITIN (UBI) promoter showed similar phenotypes to the rHb-D2 mutant. These results confirmed that HB-D2 is the causal gene responsible for the mutant phenotypes. Finally, a survey of 1397 wheat accessions showed that the complementary sites for miRNA165/166 in all three HB2 homoeologs are highly conserved. Our results suggest that HB2 plays an important role in regulating growth and development in wheat.
•An innovative assembled self-centering buckling restrained brace (ASC-BRB) with controllable initial stiffness is proposed and validated by experiments.•Compared with the existing self-centering ...brace, the ASC-BRB can effectively mitigate structural peak floor acceleration under earthquake ground motions.•Effects of two design parameters on the hysteretic behavior of ASC-BRB is investigated.•Recommended values of the brace design parameters are provided based on parametric analysis results of seismic responses of steel braced frames incorporating ASC-BRBs.
An innovative assembled self-centering buckling-restrained brace (ASC-BRB) with controllable initial stiffness is introduced. The brace consists of a self-centering system and an energy dissipation system. Unlike existing post-tensioned self-centering energy dissipation braces, whose initial stiffness has high uncertainty and is sensitive to machining errors, the proposed ASC-BRB can obtain highly controllable initial stiffness because of its unique working mechanism. Therefore, structural seismic response uncertainties can be reduced significantly. The configuration, working mechanism, and theoretical restoring force model of the ASC-BRB are first presented. Quasi-static tests are then conducted to examine the feasibility of the brace, and typical flag-shaped hysteretic behavior and stable energy dissipation capability are observed. The main components of the ASC-BRB keep intact after repeated loadings, except for the core plates, which are damaged; however, the core plates can be easily replaced. This observation highlights the superiority of the ASC-BRB in terms of damage concentration and high recoverability. The proposed theoretical restoring force model can accurately predict the hysteretic response of the brace, especially for the initial stiffness, with the predicted value being within 5 % of the experimental value. A simplified numerical model is developed and used in a parametric study conducted to examine the effects of two key design parameters on the brace behavior. Furthermore, the effect of machining errors on the initial stiffness of the ASC-BRB is studied. An analysis of steel frames with ASC-BRBs indicates that the ASC-BRB can effectively reduce the residual inter-story drift and help achieve a peak floor acceleration response comparable to that of the frame with BRBs. However, the peak inter-story drift is amplified owing to the lower initial stiffness of the proposed brace. On the basis of a system-level parametric analysis, recommended optimized design parameters of the ASC-BRB are presented to facilitate efficient control of structural seismic responses.
In this study, we focus on two types of self-centering buckling-restrained braces (SC-BRBs), which are post-tensioned (PT) SC-BRB and disc-spring-based SC-BRB, and develop a seismic design method for ...steel braced frames with these braces according to the displacement-based design theory. The whole independent parameters that describe the hysteretic behavior of the SC-BRBs are first determined. Then nonlinear time history analysis (NLTHA) is conducted to explore the effects of these hysteretic parameters on the ductility demands of the nonlinear single-degree-of-freedom (SDOF) system. Based on the analysis results, a ductility demand spectral model is developed, followed by a nonlinear displacement ratio spectral model. Subsequently, the seismic design procedure for SC-BRB frames is proposed based on the two spectral models. Finally, a total of 24 six-story steel frames with the two types of SC-BRBs, two target inter-story drifts, and different parameter combinations are designed at the maximum considered earthquake (MCE) level. The pushover analysis and NLTHA results indicate that a smaller strength ratio β and a larger initial stiffness ratio αs are beneficial for reducing the base shear and obtain an economical design when the designed frames achieve the same target inter-story drift. Considering the initial stiffness of the SC-BRBs is highly sensitive to machining errors, it is recommended that the value of β be taken within 0.25 to reduce the influence of the initial stiffness uncertainty of the braces on seismic design results. Moreover, controlling β within 0.25 also helps to reduce the higher-mode effect and peak floor acceleration responses of the designed structures effectively.
•The whole independent hysteretic parameters that describe the hysteretic behavior of self-centering buckling-restrained braces (SC-BRBs) are determined.•The ductility demand spectral model and nonlinear displacement ratio spectral model for designing SC-BRB frames are developed.•A displacement-based seismic design procedure for steel braced frames with post-tensioned and disc-spring-based SC-BRBs is proposed.•The coupling effects of the energy dissipation capacity and the initial stiffness ratio of SC system on the design results are investigated.
In order to facilitate the replacement of damaged components and prevent the weak-story mechanism of frame structure after strong earthquakes, a novel assembled self-centering buckling-restrained ...brace (ASC-BRB) is proposed in this paper. The proposed bracing system is comprised of the buckling-restrained brace (BRB) system and the self-centering (SC) system. The SC system consists of two sets of steel strands and one group of disc springs stacked in series to achieve the goal of large deformability and post-hardening behavior. The detailed configuration, fundamental working mechanism, and restoring force model of the ASC-BRB are first presented. Different from SC systems with bilinear elastic behavior of existing SC-BRBs, the SC system of ASC-BRB exhibits trilinear elastic behavior due to its special configuration. Then, quasi-static tests are conducted to validate the effectiveness of the proposed ASC-BRB. The experimental results indicate that the ASC-BRB has a flag-shaped hysteretic response with excellent self-centering capability, stable energy dissipation capability, and appreciable deformation capacity with a maximum ductility coefficient of 25.58. More importantly, the specimen can exhibit the anticipated post-hardening behavior. The refined numerical model of ASC-BRB is established and verified by the experimental results, which can effectively analyze the mechanical behavior of the main components of ASC-BRB, making up for the deficiency of the tests. According to the problems discovered in the tests and numerical analyses, an improved configuration of the ASC-BRB is proposed and validated by the numerical simulation of the BRB system before and after improvement. The numerical results indicate that the improved BRB system exhibits more stable hysteretic behavior, and the stress levels of the inner and outer tubes become much lower after replacing 1-shaped cores with steel angle cores.
•An innovative assembled self-centering buckling restrained brace (ASC-BRB) with high post-yield stiffness was proposed.•Experimental results indicated that the proposed ASC-BRB exhibited stable hysteretic behavior, appreciable self-centering capability, large deformability, and prominent post-hardening behavior.•The theoretical restoring force model of the ASC-BRB coincided well with the experimental hysteretic curve.•The refined numerical model could effectively analyze the mechanical behavior of the main components of the ASC-BRB.•An improved configuration of the ASC-BRB was proposed and validated by the numerical simulation.
SUMMARY
Precise regulation of flowering time is critical for cereal crops to synchronize reproductive development with optimum environmental conditions, thereby maximizing grain yield. The ...plant‐specific gene GIGANTEA (GI) plays an important role in the control of flowering time, with additional functions on the circadian clock and plant stress responses. In this study, we show that GI loss‐of‐function mutants in a photoperiod‐sensitive tetraploid wheat background exhibit significant delays in heading time under both long‐day (LD) and short‐day photoperiods, with stronger effects under LD. However, this interaction between GI and photoperiod is no longer observed in isogenic lines carrying either a photoperiod‐insensitive allele in the PHOTOPERIOD1 (PPD1) gene or a loss‐of‐function allele in EARLY FLOWERING 3 (ELF3), a known repressor of PPD1. These results suggest that the normal circadian regulation of PPD1 is required for the differential effect of GI on heading time in different photoperiods. Using crosses between mutant or transgenic plants of GI and those of critical genes in the flowering regulation pathway, we show that GI accelerates wheat heading time by promoting FLOWERING LOCUS T1 (FT1) expression via interactions with ELF3, VERNALIZATION 2 (VRN2), CONSTANS (CO), and the age‐dependent microRNA172‐APETALA2 (AP2) pathway, at both transcriptional and protein levels. Our study reveals conserved GI mechanisms between wheat and Arabidopsis but also identifies specific interactions of GI with the distinctive photoperiod and vernalization pathways of the temperate grasses. These results provide valuable knowledge for modulating wheat heading time and engineering new varieties better adapted to a changing environment.
Significance Statement
The role of GIGANTEA (GI) in the Arabidopsis photoperiodic pathway is well characterized, but its role in the divergent photoperiodic pathway of the temperate grasses remains unknown. We demonstrate that, in wheat, GI promotes heading time through multiple interconnected pathways, including grass‐specific interactions with the vernalization gene VRN2 and with PPD1, the key gene in wheat photoperiod pathway, as well as complex interactions with ELF3, CO, and the miR172‐AP2 pathway that are conserved with Arabidopsis.
Inflorescence architecture is an important determinant of crop productivity. The number of spikelets produced by the wheat inflorescence meristem (IM) before its transition to a terminal spikelet ...(TS) influences the maximum number of grains per spike. Wheat MADS-box genes VERNALIZATION 1 (VRN1) and FRUITFULL 2 (FUL2) (in the SQUAMOSA-clade) are essential to promote the transition from IM to TS and for spikelet development. Here we show that SQUAMOSA genes contribute to spikelet identity by repressing MADS-box genes VEGETATIVE TO REPRODUCTIVE TRANSITION 2 (VRT2), SHORT VEGETATIVE PHASE 1 (SVP1), and SVP3 in the SVP clade. Constitutive expression of VRT2 resulted in leafy glumes and lemmas, reversion of spikelets to spikes, and downregulation of MADS-box genes involved in floret development, whereas the vrt2 mutant reduced vegetative characteristics in spikelets of squamosa mutants. Interestingly, the vrt2 svp1 mutant showed similar phenotypes to squamosa mutants regarding heading time, plant height, and spikelets per spike, but it exhibited unusual axillary inflorescences in the elongating stem. We propose that SQUAMOSA-SVP interactions are important to promote heading, formation of the TS, and stem elongation during the early reproductive phase, and that downregulation of SVP genes is then necessary for normal spikelet and floral development. Manipulating SVP and SQUAMOSA genes can contribute to engineering spike architectures with improved productivity.
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