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Qiao L, Zhang X, Li X, Yang Z, Li R, Jia J, Yan L, Chang Z. Genetic incorporation of genes for the optimal plant architecture in common wheat. Mol Breed 2022; 42:66. [PMID: 37313009 PMCID: PMC10248654 DOI: 10.1007/s11032-022-01336-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2022] [Accepted: 10/03/2022] [Indexed: 06/15/2023]
Abstract
Wheat grain yield is affected by plant height, which is the total length of spike, the uppermost internode, and other elongated internodes. In this study, a population of recombinant inbred lines generated from a cross between two advanced winter wheat breeding lines were phenotyped over four locations/years and genotyped by using markers of genotyping-by-sequencing (GBS) and Diversity Array Technology (DArT) for mapping of genes for three traits, including spike length, the uppermost internode length, and plant height. Five genomic regions or quantitative trait loci (QTLs) were associated with candidate genes for these traits. A major QTL was associated with Q5A, and two novel haplotypes of Q5A were identified, one for a single nucleotide polymorphism (SNP) at position -2,149 in promoter region and the other for copy number variation. Compared with one copy Q5A on chromosome 5A in Chinese Spring, the novel haplotype of Q5A with two copies Q5A was found to generate spikes that are extremely compacted. A major QTL was associated with allelic variation in the recessive vrn-A1 alleles involving in protein sequences, and this QTL was associated with increased uppermost internode length but not with plant height. A major QTL for plant height was associated with Rht-B1b on chromosome 4B, but its effects could be compromised by two new minor QTLs on chromosome 7. Collectively, the favorable alleles from the four loci can be used to establish the optimal plant height in wheat. Supplementary Information The online version contains supplementary material available at 10.1007/s11032-022-01336-2.
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Affiliation(s)
- Linyi Qiao
- College of Agronomy, Shanxi Agricultural University, Taiyuan, 030031 Shanxi China
- Department of Plant and Soil Sciences, Oklahoma State University, Stillwater, OK 74078 USA
| | - Xiaojun Zhang
- College of Agronomy, Shanxi Agricultural University, Taiyuan, 030031 Shanxi China
| | - Xin Li
- College of Agronomy, Shanxi Agricultural University, Taiyuan, 030031 Shanxi China
| | - Zujun Yang
- School of Life Science and Technology, Science and Technology of China, University of Electronic, Chengdu, 610054 China
| | - Rui Li
- College of Agronomy, Shanxi Agricultural University, Taiyuan, 030031 Shanxi China
| | - Juqing Jia
- College of Agronomy, Shanxi Agricultural University, Taiyuan, 030031 Shanxi China
| | - Liuling Yan
- Department of Plant and Soil Sciences, Oklahoma State University, Stillwater, OK 74078 USA
| | - Zhijian Chang
- College of Agronomy, Shanxi Agricultural University, Taiyuan, 030031 Shanxi China
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Zhang J, Xiong H, Guo H, Li Y, Xie X, Xie Y, Zhao L, Gu J, Zhao S, Ding Y, Liu L. Identification of the Q Gene Playing a Role in Spike Morphology Variation in Wheat Mutants and Its Regulatory Network. Front Plant Sci 2022; 12:807731. [PMID: 35087560 PMCID: PMC8787668 DOI: 10.3389/fpls.2021.807731] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 12/13/2021] [Indexed: 05/27/2023]
Abstract
The wheat AP2 family gene Q controls domestication traits, including spike morphology and threshability, which are critical for the widespread cultivation and yield improvement of wheat. Although many studies have investigated the molecular mechanisms of the Q gene, its direct target genes, especially those controlling spike morphology, are not clear, and its regulatory pathways are not well established. In this study, we conducted gene mapping of a wheat speltoid spike mutant and found that a new allele of the Q gene with protein truncation played a role in spike morphology variation in the mutant. Dynamic expression levels of the Q gene throughout the spike development process suggested that the transcript abundances of the mutant were decreased at the W6 and W7 scales compared to those of the WT. We identified several mutation sites on the Q gene and showed that mutations in different domains resulted in distinct phenotypes. In addition, we found that the Q gene produced three transcripts via alternative splicing and that they exhibited differential expression patterns in nodes, internodes, flag leaves, and spikes. Finally, we identified several target genes directly downstream of Q, including TaGRF1-2D and TaMGD-6B, and proposed a possible regulatory network. This study uncovered the target genes of Q, and the results can help to clarify the mechanism of wheat spike morphology and thereby improve wheat grain yield.
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Vavilova V, Konopatskaia I, Blinov A, Kondratenko EY, Kruchinina YV, Goncharov NP. Genetic variability of spelt factor gene in Triticum and Aegilops species. BMC Plant Biol 2020; 20:310. [PMID: 33050874 PMCID: PMC7556929 DOI: 10.1186/s12870-020-02536-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 06/29/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND Threshability, rachis fragility and spike shape are critical traits for the domestication and evolution of wheat, determining the crop yield and efficiency of the harvest. Spelt factor gene Q controls a wide range of domestication-related traits in polyploid wheats, including those mentioned above. The main goal of the present study was to characterise the Q gene for uninvestigated accessions of wheats, including four endemics, and Aegilops accessions, and to analyze the species evolution based on differences in Q gene sequences. RESULTS We have studied the spike morphology for 15 accessions of wheat species, including four endemics, namely Triticum macha, T. tibetanum, T. aestivum ssp. petropavlovskyi and T. spelta ssp. yunnanense, and 24 Aegilops accessions, which are donors of B and D genomes for polyploid wheat. The Q-5A, q-5D and q-5S genes were investigated, and a novel allele of the Q-5A gene was found in accessions of T. tibetanum (KU510 and KU515). This allele was similar to the Q allele of T. aestivum cv. Chinese Spring but had an insertion 161 bp in length within exon 5. This insertion led to a frameshift and premature stop codon formation. Thus, the T. tibetanum have spelt spikes, which is probably determined by the gene Tg, rather than Q. We determined the variability within the q-5D genes among hexaploid wheat and their D genome donor Aegilops tauschii. Moreover, we studied the accessions C21-5129, KU-2074, and K-1100 of Ae. tauschii ssp. strangulata, which could be involved in the origin of hexaploid wheats. CONCLUSIONS The variability and phylogenetic relationships of the Q gene sequences studied allowed us to clarify the relationships between species of the genus Triticum and to predict the donor of the D genome among the Ae. tauschii accessions. Ae. tauschii ssp. strangulata accessions C21-5129, KU-2074 and K-1100 are the most interesting among the analysed accessions, since their partial sequence of q-5D is identical to the q-5D of T. aestivum cv. Chinese Spring. This result indicates that the donor is Ae. tauschii ssp. strangulata but not Ae. tauschii ssp. tauschii. Our analysis allowed us to clarify the phylogenetic relationships in the genus Triticum.
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Affiliation(s)
- Valeriya Vavilova
- Institute of Cytology and Genetics SB RAS, Novosibirsk, Russian Federation.
| | - Irina Konopatskaia
- Institute of Cytology and Genetics SB RAS, Novosibirsk, Russian Federation
| | - Alexandr Blinov
- Institute of Cytology and Genetics SB RAS, Novosibirsk, Russian Federation
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Madsen CK, Brinch-Pedersen H. A novel wheat q' allele identified by forward genetic in silico TILLING. J Plant Physiol 2020; 251:153221. [PMID: 32590253 DOI: 10.1016/j.jplph.2020.153221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 06/09/2020] [Accepted: 06/09/2020] [Indexed: 06/11/2023]
Abstract
The major wheat domestication allele Q (encoding an APETALA2 like transcription factor) is responsible for the free threshing and square-headed spikes of modern wheat. Wild type q and null q' alleles cause a reversal to the speltoid phenotype. Q pleiotropically affects additional yield and quality traits so genetic variation in Q and its interaction partners remain important for crop improvement. Here we report the discovery of a novel q' allele that contribute to the molecular characterization of Q. This induced mutation cause an Ala→Thr substitution at a highly conserved position in the first of two APETALA2 like domains of the Q protein. The mutation correlates with a speltoid phenotype as expected for a loss of Q function. Thus, it is demonstrated that the first APETALA2 like domain is essential for Q function. The phenotype was discovered in a mutant from an in silico TILLING population and the causative mutation could be identified in the existing sequence data. This report therefore provides an example of a forward genetic application of in silico TILLING.
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Affiliation(s)
- Claus Krogh Madsen
- Section of Crop Genetics and Biotechnology, Department of Agroecology, Aarhus University. Forsøgsvej 1, 4200 Slagelse, Denmark.
| | - Henrik Brinch-Pedersen
- Section of Crop Genetics and Biotechnology, Department of Agroecology, Aarhus University. Forsøgsvej 1, 4200 Slagelse, Denmark
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Zhang Z, Li A, Song G, Geng S, Gill BS, Faris JD, Mao L. Comprehensive analysis of Q gene near-isogenic lines reveals key molecular pathways for wheat domestication and improvement. Plant J 2020; 102:299-310. [PMID: 31778224 DOI: 10.1111/tpj.14624] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Revised: 10/14/2019] [Accepted: 11/12/2019] [Indexed: 06/10/2023]
Abstract
The wheat AP2-like transcription factor gene Q has played a major role in domestication by conferring the free-threshing character and pleiotropically affecting numerous other traits. However, little information is known regarding the molecular mechanisms associated with the regulation of these traits by Q, especially for the structural determination of threshability. Here, transcriptome analysis of immature spike tissues in three lines nearly isogenic for Q revealed over 3000 differentially expressed genes (DEGs) involved in a number of pathways. Using phenotypic, microscopic, transcriptomic, and tissue-specific gene expression analyses, we demonstrated that Q governs threshability through extensive modification of wheat glumes including their structure, cell wall thickness, and chemical composition. Critical DEGs and pathways involved in secondary cell wall synthesis and regulation of the chemical composition of glumes were identified. We also showed that the mutation giving rise to the Q allele synchronized the expression of genes for micro-sporogenesis that affected pollen fertility, and may determine the final grain number for wheat spikes. Transcriptome dissection of genes and genetic pathways regulated by Q should further our understanding of wheat domestication and improvement.
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Affiliation(s)
- Zengcui Zhang
- Cereal Crops Research Unit, Edward T. Schafer Agricultural Research Center, USDA-ARS, Fargo, ND, 58102, USA
| | - Aili Li
- Institute of Crop Science (ICS), Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100081, China
| | - Gaoyuan Song
- Institute of Crop Science (ICS), Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100081, China
| | - Shuaifeng Geng
- Institute of Crop Science (ICS), Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100081, China
| | - Bikram S Gill
- Wheat Genetics Resource Center and Department of Plant Pathology, Kansas State University, Manhattan, 66506, KS, USA
| | - Justin D Faris
- Cereal Crops Research Unit, Edward T. Schafer Agricultural Research Center, USDA-ARS, Fargo, ND, 58102, USA
| | - Long Mao
- Institute of Crop Science (ICS), Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100081, China
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6
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Jiang YF, Chen Q, Wang Y, Guo ZR, Xu BJ, Zhu J, Zhang YZ, Gong X, Luo CH, Wu W, Liu CH, Kong L, Deng M, Jiang QT, Lan XJ, Wang JR, Chen GY, Zheng YL, Wei YM, Qi PF. Re-acquisition of the brittle rachis trait via a transposon insertion in domestication gene Q during wheat de-domestication. New Phytol 2019; 224:961-973. [PMID: 31168798 DOI: 10.1111/nph.15977] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Accepted: 05/28/2019] [Indexed: 05/18/2023]
Abstract
De-domestication is a unique evolutionary process during which crops re-acquire wild-like traits to survive and persist in agricultural fields without the need for human cultivation. The re-acquisition of seed dispersal mechanisms is crucial for crop de-domestication. Common wheat is an important cereal crop worldwide. Tibetan semi-wild wheat is a potential de-domesticated common wheat subspecies. However, the crucial genes responsible for its brittle rachis trait have not been identified. Genetic mapping, functional analyses and phylogenetic analyses were completed to identify the gene associated with Qbr.sau-5A, which is a major locus for the brittle rachis trait of Tibetan semi-wild wheat. The cloned Qbr.sau-5A gene is a new Q allele (Qt ) with a 161-bp transposon insertion in exon 5. Although Qt is expressed normally, its encoded peptide lacks some key features of the APETALA2 family. The abnormal functions of Qt in developing wheat spikes result in brittle rachises. Phylogenetic and genotyping analyses confirmed that Qt originated from Q in common wheat and is naturally distributed only in Tibetan semi-wild wheat populations. The identification of Qt provides new evidence regarding the origin of Tibetan semi-wild wheat, and new insights into the re-acquisition of wild traits during crop de-domestication.
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Affiliation(s)
- Yun-Feng Jiang
- State Key Laboratory of Crop Genetics of Disease Resistance and Disease Control, Chengdu, Sichuan, 611130, China
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China
| | - Qing Chen
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China
| | - Yan Wang
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China
| | - Zhen-Ru Guo
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China
| | - Bin-Jie Xu
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China
| | - Jing Zhu
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China
| | - Ya-Zhou Zhang
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China
| | - Xi Gong
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China
| | - Cui-Hua Luo
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China
| | - Wang Wu
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China
| | - Cai-Hong Liu
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China
| | - Li Kong
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China
| | - Mei Deng
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China
| | - Qian-Tao Jiang
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China
| | - Xiu-Jin Lan
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China
| | - Ji-Rui Wang
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China
| | - Guo-Yue Chen
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China
| | - You-Liang Zheng
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China
| | - Yu-Ming Wei
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China
| | - Peng-Fei Qi
- State Key Laboratory of Crop Genetics of Disease Resistance and Disease Control, Chengdu, Sichuan, 611130, China
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China
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Curzon AY, Chandrasekhar K, Nashef YK, Abbo S, Bonfil DJ, Reifen R, Bar-El S, Avneri A, Ben-David R. Distinguishing between Bread Wheat and Spelt Grains Using Molecular Markers and Spectroscopy. J Agric Food Chem 2019; 67:3837-3841. [PMID: 30807140 DOI: 10.1021/acs.jafc.9b00131] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The increasing demand for spelt products requires the baking industry to develop accurate and efficient tools to differentiate between spelt and bread wheat grains. We subjected a 272-sample spelt-bread wheat set to several potential diagnostic methods. DNA markers for γ-gliadin-D ( GAG56D), γ-gliadin-B ( GAG56B), and the Q-gene were used, alongside phenotypic assessment of ease-of-threshing and near-infrared spectroscopy (NIRS). The GAG56B and GAG56D markers demonstrated low diagnostic power in comparison to the Q-gene genotyping, which showed full accordance with the threshing phenotype, providing a highly accurate distinction between bread wheat and spelt kernels. A highly reliable Q classification was based on a three-waveband NIR model [Kappa (0.97), R-square (0.93)], which suggested that this gene influences grain characteristics. Our data ruled out a protein concentration bias of the NIRS-based diagnosis. These findings highlight the Q gene and NIRS as important, valuable, but simple tools for distinguishing between bread wheat and spelt.
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Affiliation(s)
- A Y Curzon
- Department of Vegetable and Field Crops, Institute of Plant Sciences , Agricultural Research Organization (ARO)-Volcani Center , Rishon LeZion 7528809 , Israel
- The Levi Eshkol School of Agriculture , The Hebrew University of Jerusalem , Rehovot 7610001 , Israel
| | - K Chandrasekhar
- Department of Vegetable and Field Crops, Institute of Plant Sciences , Agricultural Research Organization (ARO)-Volcani Center , Rishon LeZion 7528809 , Israel
| | - Y K Nashef
- Department of Vegetable and Field Crops, Institute of Plant Sciences , Agricultural Research Organization (ARO)-Volcani Center , Rishon LeZion 7528809 , Israel
| | - S Abbo
- The Levi Eshkol School of Agriculture , The Hebrew University of Jerusalem , Rehovot 7610001 , Israel
| | - D J Bonfil
- Department of Vegetable and Field Crops, Institute of Plant Sciences , Agricultural Research Organization (ARO)-Gilat Research Center , Gilat 8531100 , Israel
| | - R Reifen
- The School of Nutritional Sciences, The Robert H. Smith Faculty of Agriculture, Food and Environment , The Hebrew University of Jerusalem , Rehovot 7610001 , Israel
| | - S Bar-El
- The School of Nutritional Sciences, The Robert H. Smith Faculty of Agriculture, Food and Environment , The Hebrew University of Jerusalem , Rehovot 7610001 , Israel
| | - A Avneri
- The Levi Eshkol School of Agriculture , The Hebrew University of Jerusalem , Rehovot 7610001 , Israel
| | - R Ben-David
- Department of Vegetable and Field Crops, Institute of Plant Sciences , Agricultural Research Organization (ARO)-Volcani Center , Rishon LeZion 7528809 , Israel
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8
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Liu P, Liu J, Dong H, Sun J. Functional regulation of Q by microRNA172 and transcriptional co-repressor TOPLESS in controlling bread wheat spikelet density. Plant Biotechnol J 2018; 16:495-506. [PMID: 28703466 PMCID: PMC5787848 DOI: 10.1111/pbi.12790] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 06/23/2017] [Accepted: 07/04/2017] [Indexed: 05/20/2023]
Abstract
Bread wheat (Triticum aestivum) spike architecture is an important agronomic trait. The Q gene plays a key role in the domestication of bread wheat spike architecture. However, the regulatory mechanisms of Q expression and transcriptional activity remain largely unknown. In this study, we show that overexpression of bread wheat tae-miR172 caused a speltoid-like spike phenotype, reminiscent of that in wheat plants with the q gene. The reduction in Q transcript levels in the tae-miR172 overexpression transgenic bread wheat lines suggests that the Q expression can be suppressed by tae-miR172 in bread wheat. Indeed, our RACE analyses confirmed that the Q mRNA is targeted by tae-miR172 for cleavage. According to our analyses, the Q protein is localized in nucleus and confers transcriptional repression activity. Meanwhile, the Q protein could physically interact with the bread wheat transcriptional co-repressor TOPLESS (TaTPL). Specifically, the N-terminal ethylene-responsive element binding factor-associated amphiphilic repression (EAR) (LDLNVE) motif but not the C-terminal EAR (LDLDLR) motif of Q protein mediates its interaction with the CTLH motif of TaTPL. Moreover, we show that the N-terminal EAR motif of Q protein is also essentially required for the transcriptional repression activity of Q protein. Taken together, we reveal the functional regulation of Q protein by tae-miR172 and transcriptional co-repressor TaTPL in controlling the bread wheat spike architecture.
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Affiliation(s)
- Pan Liu
- National Key Facility for Crop Gene Resources and Genetic ImprovementInstitute of Crop ScienceChinese Academy of Agricultural SciencesBeijingChina
| | - Jie Liu
- National Key Facility for Crop Gene Resources and Genetic ImprovementInstitute of Crop ScienceChinese Academy of Agricultural SciencesBeijingChina
| | - Huixue Dong
- National Key Facility for Crop Gene Resources and Genetic ImprovementInstitute of Crop ScienceChinese Academy of Agricultural SciencesBeijingChina
| | - Jiaqiang Sun
- National Key Facility for Crop Gene Resources and Genetic ImprovementInstitute of Crop ScienceChinese Academy of Agricultural SciencesBeijingChina
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9
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Debernardi JM, Lin H, Chuck G, Faris JD, Dubcovsky J. microRNA172 plays a crucial role in wheat spike morphogenesis and grain threshability. Development 2017; 144:1966-1975. [PMID: 28455375 PMCID: PMC5482987 DOI: 10.1242/dev.146399] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 04/18/2017] [Indexed: 12/12/2022]
Abstract
Wheat domestication from wild species involved mutations in the Q gene. The q allele (wild wheats) is associated with elongated spikes and hulled grains, whereas the mutant Q allele (domesticated wheats) confers subcompact spikes and free-threshing grains. Previous studies showed that Q encodes an AP2-like transcription factor, but the causal polymorphism of the domestication traits remained unclear. Here, we show that the interaction between microRNA172 (miR172) and the Q allele is reduced by a single nucleotide polymorphism in the miRNA binding site. Inhibition of miR172 activity by a miRNA target mimic resulted in compact spikes and transition from glumes to florets in apical spikelets. By contrast, overexpression of miR172 was sufficient to induce elongated spikes and non-free-threshing grains, similar to those observed in three Q loss-of-function mutations. These lines showed transitions from florets to glumes in the basal spikelets. These localized homeotic changes were associated with opposing miR172/Q gradients along the spike. We propose that the selection of a nucleotide change at the miR172 binding site of Q contributed to subcompact spikes and free-threshing grains during wheat domestication. Highlighted Article: A nucleotide change in the microRNA172 binding site of the AP2 gene Q played a critical role in wheat domestication and the origin of free-threshing modern wheats. See also Greenwood et al. in this issue.
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Affiliation(s)
| | - Huiqiong Lin
- Department of Plant Sciences, University of California, Davis, CA 95616, USA
| | - George Chuck
- Plant Gene Expression Center, University of California, Berkeley, Albany, CA 94710, USA
| | - Justin D Faris
- USDA-ARS Cereal Crops Research Unit, Northern Crop Science Laboratory, Fargo, ND 58102, USA
| | - Jorge Dubcovsky
- Department of Plant Sciences, University of California, Davis, CA 95616, USA .,Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
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Olavesen KK, Lindstedt BA, Løbersli I, Brandal LT. Expression of Shiga toxin 2 (Stx2) in highly virulent Stx-producing Escherichia coli (STEC) carrying different anti-terminator (q) genes. Microb Pathog 2016; 97:1-8. [PMID: 27208749 DOI: 10.1016/j.micpath.2016.05.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 05/12/2016] [Accepted: 05/17/2016] [Indexed: 11/20/2022]
Abstract
Shiga toxins (Stx) are key virulence factors of Shiga toxin-producing Escherichia coli (STEC) during development of haemolytic uremic syndrome (HUS). It has been suggested that not only specific stx2 subtypes, but also the amount of Stx2 expressed might be essential for STEC pathogenicity. We aimed to investigate if various anti-terminator (q) genes might influence the expression level of Stx2 in highly virulent STEC. A multiplex PCR detecting q933, q21, and qO111 was run on 20 stx2a-positive STEC strains, of which 18 were HUS associated serotypes (HAS) and two non-HAS. Relative expression of Stx2 mRNA was assessed for all strains, both in non-induced and induced (mitomycin C) state. The HAS STEC carried either q933 (n = 8), qO111 (n = 8), or both (n = 2). In basal state, no STEC strains showed higher expression of Stx2 mRNA than the calibrator EDL933 (non-sorbitol fermenting (NSF) O157:H7carrying q933). Variations among strains were not associated with different q genes present, but rather related to specific serogroups. In induced state, O104:H4 strains (q933) showed higher Stx2 mRNA level than EDL933, whereas sorbitol fermenting (SF) O157:H- (qO111) and O121:H? (q933) STEC showed levels comparable with EDL933. An association between the presence of q933 and higher Stx2 level was seen within some HAS, but not all. Interestingly, the O103:H25 STEC strains, responsible for a HUS outbreak in Norway, carried both q933 and qO111. However, the Stx2 mRNA level in these strains was significantly lower than EDL933 in both states, indicating that other factors than the level of Stx2 might explain the aggressiveness of these bacteria. The two non-HAS STEC did not carry any of the examined q genes. In induced state, these bacteria showed the lowest Stx2 mRNA level compared to EDL933. One of the non-HAS STEC was not induced by mitomycin C, suggesting that stx2a might be located on a defect bacteriophage. No association between specific q genes and Stx2 mRNA expression level was revealed in stx2a-positive HAS STEC. Our results suggest that other factor(s) than specific q genes might influence the level of Stx2 produced in highly virulent STEC.
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Affiliation(s)
- Kristoffer K Olavesen
- Department of Foodborne Infections, Norwegian Institute of Public Health, Oslo, Norway
| | - Bjørn-Arne Lindstedt
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Aas, Norway
| | - Inger Løbersli
- Department of Foodborne Infections, Norwegian Institute of Public Health, Oslo, Norway
| | - Lin T Brandal
- Department of Foodborne Infections, Norwegian Institute of Public Health, Oslo, Norway.
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