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Rychel-Bielska S, Bielski W, Surma A, Annicchiarico P, Belter J, Kozak B, Galek R, Harzic N, Książkiewicz M. A GWAS study highlights significant associations between a series of indels in a FLOWERING LOCUS T gene promoter and flowering time in white lupin (Lupinus albus L.). BMC PLANT BIOLOGY 2024; 24:722. [PMID: 39075363 PMCID: PMC11285409 DOI: 10.1186/s12870-024-05438-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 07/19/2024] [Indexed: 07/31/2024]
Abstract
BACKGROUND White lupin (Lupinus albus L.) is a high-protein Old World grain legume with remarkable food and feed production interest. It is sown in autumn or early spring, depending on the local agroclimatic conditions. This study aimed to identify allelic variants associated with vernalization responsiveness, in order to improve our knowledge of legume flowering regulatory pathways and develop molecular selection tools for the desired phenology as required for current breeding and adaptation to the changing climate. RESULTS Some 120 white lupin accessions originating from a wide range of environments of Europe, Africa, and Asia were phenotyped under field conditions in three environments with different intensities of vernalization, namely, a Mediterranean and a subcontinental climate sites of Italy under autumn sowing, and a suboceanic climate site of France under spring sowing. Two hundred sixty-two individual genotypes extracted from them were phenotyped in a greenhouse under long-day photoperiod without vernalization. Phenology data, and marker data generated by Diversity Arrays Technology sequencing (DArT-seq) and by PCR-based screening targeting published quantitative trait loci (QTLs) from linkage map and newly identified insertion/deletion polymorphisms in the promoter region of the FLOWERING LOCUS T homolog, LalbFTc1 gene (Lalb_Chr14g0364281), were subjected to a genome-wide association study (GWAS). Population structure followed differences in phenology and isolation by distance pattern. The GWAS highlighted numerous loci significantly associated with flowering time, including four LalbFTc1 gene promoter deletions: 2388 bp and 2126 bp deletions at the 5' end, a 264 bp deletion in the middle and a 28 bp deletion at the 3' end of the promoter. Besides LalbFTc1 deletions, this set contained DArT-seq markers that matched previously published major QTLs in chromosomes Lalb_Chr02, Lalb_Chr13 and Lalb_Chr16, and newly discovered QTLs in other chromosomes. CONCLUSIONS This study highlighted novel QTLs for flowering time and validated those already published, thereby providing novel evidence on the convergence of FTc1 gene functional evolution into the vernalization pathway in Old World lupin species. Moreover, this research provided the set of loci specific for extreme phenotypes (the earliest or the latest) awaiting further implementation in marker-assisted selection for spring- or winter sowing.
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Affiliation(s)
- Sandra Rychel-Bielska
- Department of Genetics, Plant Breeding and Seed Production, Wroclaw University of Environmental and Life Sciences, Plac Grunwaldzki 24A, Wrocław, 50-363, Poland
| | - Wojciech Bielski
- Department of Genetics and Plant Breeding, Poznań University of Life Sciences, Dojazd 11, Poznan, 60-632, Poland
- Department of Gene Structure and Function, Institute of Plant Genetics, Polish Academy of Sciences, Strzeszynska 34, Poznań, 60-479, Poland
| | - Anna Surma
- Department of Gene Structure and Function, Institute of Plant Genetics, Polish Academy of Sciences, Strzeszynska 34, Poznań, 60-479, Poland
| | - Paolo Annicchiarico
- Council for Agricultural Research and Economics, Research Centre for Animal Production and Aquaculture, Viale Piacenza 29, Lodi, 26900, Italy
| | - Jolanta Belter
- Department of Gene Structure and Function, Institute of Plant Genetics, Polish Academy of Sciences, Strzeszynska 34, Poznań, 60-479, Poland
| | - Bartosz Kozak
- Department of Genetics, Plant Breeding and Seed Production, Wroclaw University of Environmental and Life Sciences, Plac Grunwaldzki 24A, Wrocław, 50-363, Poland
| | - Renata Galek
- Department of Genetics, Plant Breeding and Seed Production, Wroclaw University of Environmental and Life Sciences, Plac Grunwaldzki 24A, Wrocław, 50-363, Poland
| | - Nathalie Harzic
- Cérience, 1 Allée de la Sapinière, Saint Sauvant, 86600, France
| | - Michał Książkiewicz
- Department of Gene Structure and Function, Institute of Plant Genetics, Polish Academy of Sciences, Strzeszynska 34, Poznań, 60-479, Poland.
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Duk MA, Gursky VV, Samsonova MG, Surkova SY. Modeling the Flowering Activation Motif during Vernalization in Legumes: A Case Study of M. trancatula. Life (Basel) 2023; 14:26. [PMID: 38255642 PMCID: PMC10817331 DOI: 10.3390/life14010026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 12/04/2023] [Accepted: 12/19/2023] [Indexed: 01/24/2024] Open
Abstract
In many plant species, flowering is promoted by the cold treatment or vernalization. The mechanism of vernalization-induced flowering has been extensively studied in Arabidopsis but remains largely unknown in legumes. The orthologs of the FLC gene, a major regulator of vernalization response in Arabidopsis, are absent or non-functional in the vernalization-sensitive legume species. Nevertheless, the legume integrator genes FT and SOC1 are involved in the transition of the vernalization signal to meristem identity genes, including PIM (AP1 ortholog). However, the regulatory contribution of these genes to PIM activation in legumes remains elusive. Here, we presented the theoretical and data-driven analyses of a feed-forward regulatory motif that includes a vernalization-responsive FT gene and several SOC1 genes, which independently activate PIM and thereby mediate floral transition. Our theoretical model showed that the multiple regulatory branches in this regulatory motif facilitated the elimination of no-sense signals and amplified useful signals from the upstream regulator. We further developed and analyzed four data-driven models of PIM activation in Medicago trancatula in vernalized and non-vernalized conditions in wild-type and fta1-1 mutants. The model with FTa1 providing both direct activation and indirect activation via three intermediate activators, SOC1a, SOC1b, and SOC1c, resulted in the most relevant PIM dynamics. In this model, the difference between regulatory inputs of SOC1 genes was nonessential. As a result, in the M. trancatula model, the cumulative action of SOC1a, SOC1b, and SOC1c was favored. Overall, in this study, we first presented the in silico analysis of vernalization-induced flowering in legumes. The considered vernalization network motif can be supplemented with additional regulatory branches as new experimental data become available.
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Affiliation(s)
- Maria A. Duk
- Mathematical Biology and Bioinformatics Laboratory, Peter the Great Saint Petersburg Polytechnic University, 195251 St. Petersburg, Russia
- Theoretical Department, Ioffe Institute, 194021 St. Petersburg, Russia
| | - Vitaly V. Gursky
- Theoretical Department, Ioffe Institute, 194021 St. Petersburg, Russia
| | - Maria G. Samsonova
- Mathematical Biology and Bioinformatics Laboratory, Peter the Great Saint Petersburg Polytechnic University, 195251 St. Petersburg, Russia
| | - Svetlana Yu. Surkova
- Mathematical Biology and Bioinformatics Laboratory, Peter the Great Saint Petersburg Polytechnic University, 195251 St. Petersburg, Russia
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Shi M, Wang C, Wang P, Yun F, Liu Z, Ye F, Wei L, Liao W. Role of methylation in vernalization and photoperiod pathway: a potential flowering regulator? HORTICULTURE RESEARCH 2023; 10:uhad174. [PMID: 37841501 PMCID: PMC10569243 DOI: 10.1093/hr/uhad174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 08/23/2023] [Indexed: 10/17/2023]
Abstract
Recognized as a pivotal developmental transition, flowering marks the continuation of a plant's life cycle. Vernalization and photoperiod are two major flowering pathways orchestrating numerous florigenic signals. Methylation, including histone, DNA and RNA methylation, is one of the recent foci in plant development. Considerable studies reveal that methylation seems to show an increasing potential regulatory role in plant flowering via altering relevant gene expression without altering the genetic basis. However, little has been reviewed about whether and how methylation acts on vernalization- and photoperiod-induced flowering before and after FLOWERING LOCUS C (FLC) reactivation, what role RNA methylation plays in vernalization- and photoperiod-induced flowering, how methylation participates simultaneously in both vernalization- and photoperiod-induced flowering, the heritability of methylation memory under the vernalization/photoperiod pathway, and whether and how methylation replaces vernalization/photoinduction to regulate flowering. Our review provides insight about the crosstalk among the genetic control of the flowering gene network, methylation (methyltransferases/demethylases) and external signals (cold, light, sRNA and phytohormones) in vernalization and photoperiod pathways. The existing evidence that RNA methylation may play a potential regulatory role in vernalization- and photoperiod-induced flowering has been gathered and represented for the first time. This review speculates about and discusses the possibility of substituting methylation for vernalization and photoinduction to promote flowering. Current evidence is utilized to discuss the possibility of future methylation reagents becoming flowering regulators at the molecular level.
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Affiliation(s)
- Meimei Shi
- College of Horticulture, Gansu Agricultural University, Lanzhou 730070, China
| | - Chunlei Wang
- College of Horticulture, Gansu Agricultural University, Lanzhou 730070, China
| | - Peng Wang
- Vegetable and Flower Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Fahong Yun
- College of Horticulture, Gansu Agricultural University, Lanzhou 730070, China
| | - Zhiya Liu
- College of Horticulture, Gansu Agricultural University, Lanzhou 730070, China
| | - Fujin Ye
- College of Horticulture, Gansu Agricultural University, Lanzhou 730070, China
| | - Lijuan Wei
- College of Horticulture, Gansu Agricultural University, Lanzhou 730070, China
| | - Weibiao Liao
- College of Horticulture, Gansu Agricultural University, Lanzhou 730070, China
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Gretsova M, Surkova S, Kanapin A, Samsonova A, Logacheva M, Shcherbakov A, Logachev A, Bankin M, Nuzhdin S, Samsonova M. Transcriptomic Analysis of Flowering Time Genes in Cultivated Chickpea and Wild Cicer. Int J Mol Sci 2023; 24:ijms24032692. [PMID: 36769014 PMCID: PMC9916832 DOI: 10.3390/ijms24032692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 01/20/2023] [Accepted: 01/23/2023] [Indexed: 02/05/2023] Open
Abstract
Chickpea (Cicer arietinum L.) is a major grain legume and a good source of plant-based protein. However, comprehensive knowledge of flowering time control in Cicer is lacking. In this study, we acquire high-throughput transcriptome sequencing data and analyze changes in gene expression during floral transition in the early flowering cultivar ICCV 96029, later flowering C. arietinum accessions, and two wild species, C. reticulatum and C. echinospermum. We identify Cicer orthologs of A. thaliana flowering time genes and analyze differential expression of 278 genes between four species/accessions, three tissue types, and two conditions. Our results show that the differences in gene expression between ICCV 96029 and other cultivated chickpea accessions are vernalization-dependent. In addition, we highlight the role of FTa3, an ortholog of FLOWERING LOCUS T in Arabidopsis, in the vernalization response of cultivated chickpea. A common set of differentially expressed genes was found for all comparisons between wild species and cultivars. The direction of expression change for different copies of the FT-INTERACTING PROTEIN 1 gene was variable in different comparisons, which suggests complex mechanisms of FT protein transport. Our study makes a contribution to the understanding of flowering time control in Cicer, and can provide genetic strategies to further improve this important agronomic trait.
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Affiliation(s)
- Maria Gretsova
- Mathematical Biology and Bioinformatics Laboratory, Peter the Great St. Petersburg Polytechnic University, 195251 St. Petersburg, Russia
| | - Svetlana Surkova
- Mathematical Biology and Bioinformatics Laboratory, Peter the Great St. Petersburg Polytechnic University, 195251 St. Petersburg, Russia
| | - Alexander Kanapin
- Centre for Computational Biology, Peter the Great St. Petersburg Polytechnic University, 195251 St. Petersburg, Russia
| | - Anastasia Samsonova
- Centre for Computational Biology, Peter the Great St. Petersburg Polytechnic University, 195251 St. Petersburg, Russia
| | - Maria Logacheva
- Center of Life Sciences, Skolkovo Institute of Science and Technology, 121205 Moscow, Russia
| | - Andrey Shcherbakov
- Laboratory of Microbial Technology, All-Russia Research Institute for Agricultural Microbiology, 196608 St. Petersburg, Russia
| | - Anton Logachev
- Mathematical Biology and Bioinformatics Laboratory, Peter the Great St. Petersburg Polytechnic University, 195251 St. Petersburg, Russia
| | - Mikhail Bankin
- Mathematical Biology and Bioinformatics Laboratory, Peter the Great St. Petersburg Polytechnic University, 195251 St. Petersburg, Russia
| | - Sergey Nuzhdin
- Section of Molecular and Computational Biology, University of Southern California, Los Angeles, CA 90089, USA
| | - Maria Samsonova
- Mathematical Biology and Bioinformatics Laboratory, Peter the Great St. Petersburg Polytechnic University, 195251 St. Petersburg, Russia
- Correspondence:
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Meng Y, Wang C, Li Q, Ji W, Wen J, Mysore KS, Pei Y, Niu L, Lin H. DPB3 and DPB4 proteins regulate Medicago flowering and leaf anthocyanin biosynthesis. J Genet Genomics 2023:S1673-8527(23)00022-X. [PMID: 36693566 DOI: 10.1016/j.jgg.2023.01.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 12/28/2022] [Accepted: 01/10/2023] [Indexed: 01/23/2023]
Affiliation(s)
- Yingying Meng
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Chongnan Wang
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Qiqi Li
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China; College of Life Science, Shanxi University, Taiyuan, Shanxi 030006, China
| | - Wenkai Ji
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Jiangqi Wen
- Department of Plant and Soil Sciences, Institute for Agricultural Biosciences, Oklahoma State University, Ardmore, OK 73401, USA
| | - Kirankumar S Mysore
- Department of Biochemistry and Molecular Biology, Institute for Agricultural Biosciences, Oklahoma State University, Ardmore, OK 73401, USA
| | - Yanxi Pei
- College of Life Science, Shanxi University, Taiyuan, Shanxi 030006, China
| | - Lifang Niu
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
| | - Hao Lin
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
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Jaudal M, Mayo‐Smith M, Poulet A, Whibley A, Peng Y, Zhang L, Thomson G, Trimborn L, Jacob Y, van Wolfswinkel JC, Goldstone DC, Wen J, Mysore KS, Putterill J. MtING2 encodes an ING domain PHD finger protein which affects Medicago growth, flowering, global patterns of H3K4me3, and gene expression. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2022; 112:1029-1050. [PMID: 36178149 PMCID: PMC9828230 DOI: 10.1111/tpj.15994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 09/04/2022] [Accepted: 09/24/2022] [Indexed: 06/16/2023]
Abstract
Flowering of the reference legume Medicago truncatula is promoted by winter cold (vernalization) followed by long-day photoperiods (VLD) similar to winter annual Arabidopsis. However, Medicago lacks FLC and CO, key regulators of Arabidopsis VLD flowering. Most plants have two INHIBITOR OF GROWTH (ING) genes (ING1 and ING2), encoding proteins with an ING domain with two anti-parallel alpha-helices and a plant homeodomain (PHD) finger, but their genetic role has not been previously described. In Medicago, Mting1 gene-edited mutants developed and flowered normally, but an Mting2-1 Tnt1 insertion mutant and gene-edited Mting2 mutants had developmental abnormalities including delayed flowering particularly in VLD, compact architecture, abnormal leaves with extra leaflets but no trichomes, and smaller seeds and barrels. Mting2 mutants had reduced expression of activators of flowering, including the FT-like gene MtFTa1, and increased expression of the candidate repressor MtTFL1c, consistent with the delayed flowering of the mutant. MtING2 overexpression complemented Mting2-1, but did not accelerate flowering in wild type. The MtING2 PHD finger bound H3K4me2/3 peptides weakly in vitro, but analysis of gene-edited mutants indicated that it was dispensable to MtING2 function in wild-type plants. RNA sequencing experiments indicated that >7000 genes are mis-expressed in the Mting2-1 mutant, consistent with its strong mutant phenotypes. Interestingly, ChIP-seq analysis identified >5000 novel H3K4me3 locations in the genome of Mting2-1 mutants compared to wild type R108. Overall, our mutant study has uncovered an important physiological role of a plant ING2 gene in development, flowering, and gene expression, which likely involves an epigenetic mechanism.
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Affiliation(s)
- Mauren Jaudal
- School of Biological SciencesUniversity of AucklandPrivate Bag 92019Auckland1142New Zealand
| | - Matthew Mayo‐Smith
- School of Biological SciencesUniversity of AucklandPrivate Bag 92019Auckland1142New Zealand
| | - Axel Poulet
- Yale UniversityDepartment of MolecularCellular and Developmental BiologyFaculty of Arts and Sciences260 Whitney AvenueNew HavenCT06511USA
| | - Annabel Whibley
- School of Biological SciencesUniversity of AucklandPrivate Bag 92019Auckland1142New Zealand
| | - Yongyan Peng
- School of Biological SciencesUniversity of AucklandPrivate Bag 92019Auckland1142New Zealand
| | - Lulu Zhang
- School of Biological SciencesUniversity of AucklandPrivate Bag 92019Auckland1142New Zealand
| | - Geoffrey Thomson
- School of Biological SciencesUniversity of AucklandPrivate Bag 92019Auckland1142New Zealand
- Yale UniversityDepartment of MolecularCellular and Developmental BiologyFaculty of Arts and Sciences260 Whitney AvenueNew HavenCT06511USA
| | - Laura Trimborn
- School of Biological SciencesUniversity of AucklandPrivate Bag 92019Auckland1142New Zealand
- Institute for Plant Sciences, BiocenterUniversity of CologneZülpicher Str. 47b50674CologneGermany
| | - Yannick Jacob
- Yale UniversityDepartment of MolecularCellular and Developmental BiologyFaculty of Arts and Sciences260 Whitney AvenueNew HavenCT06511USA
| | - Josien C. van Wolfswinkel
- Yale UniversityDepartment of MolecularCellular and Developmental BiologyFaculty of Arts and Sciences260 Whitney AvenueNew HavenCT06511USA
| | - David C. Goldstone
- School of Biological SciencesUniversity of AucklandPrivate Bag 92019Auckland1142New Zealand
| | - Jiangqi Wen
- Institute for Agricultural BiosciencesOklahoma State University3210 Sam Noble ParkwayArdmoreOK73401USA
| | - Kirankumar S. Mysore
- Institute for Agricultural BiosciencesOklahoma State University3210 Sam Noble ParkwayArdmoreOK73401USA
| | - Joanna Putterill
- School of Biological SciencesUniversity of AucklandPrivate Bag 92019Auckland1142New Zealand
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Surkova SY, Samsonova MG. Mechanisms of Vernalization-Induced Flowering in Legumes. Int J Mol Sci 2022; 23:ijms23179889. [PMID: 36077286 PMCID: PMC9456104 DOI: 10.3390/ijms23179889] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 08/25/2022] [Accepted: 08/26/2022] [Indexed: 11/16/2022] Open
Abstract
Vernalization is the requirement for exposure to low temperatures to trigger flowering. The best knowledge about the mechanisms of vernalization response has been accumulated for Arabidopsis and cereals. In Arabidopsis thaliana, vernalization involves an epigenetic silencing of the MADS-box gene FLOWERING LOCUS C (FLC), which is a flowering repressor. FLC silencing releases the expression of the main flowering inductor FLOWERING LOCUS T (FT), resulting in a floral transition. Remarkably, no FLC homologues have been identified in the vernalization-responsive legumes, and the mechanisms of cold-mediated transition to flowering in these species remain elusive. Nevertheless, legume FT genes have been shown to retain the function of the main vernalization signal integrators. Unlike Arabidopsis, legumes have three subclades of FT genes, which demonstrate distinct patterns of regulation with respect to environmental cues and tissue specificity. This implies complex mechanisms of vernalization signal propagation in the flowering network, that remain largely elusive. Here, for the first time, we summarize the available information on the genetic basis of cold-induced flowering in legumes with a special focus on the role of FT genes.
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8
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Williams O, Vander Schoor JK, Butler JB, Ridge S, Sussmilch FC, Hecht VFG, Weller JL. The genetic architecture of flowering time changes in pea from wild to crop. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:3978-3990. [PMID: 35383838 PMCID: PMC9238443 DOI: 10.1093/jxb/erac132] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 04/04/2022] [Indexed: 06/14/2023]
Abstract
Change in phenology has been an important component in crop evolution, and selection for earlier flowering through a reduction in environmental sensitivity has helped broaden adaptation in many species. Natural variation for flowering in domesticated pea (Pisum sativum L.) has been noted and studied for decades, but there has been no clear account of change relative to its wild progenitor. Here we examined the genetic control of differences in flowering time between wild P. sativum ssp. humile and a typical late-flowering photoperiodic P. s. sativum accession in a recombinant inbred population under long and short photoperiods. Our results confirm the importance of the major photoperiod sensitivity locus Hr/PsELF3a and identify two other loci on chromosomes 1 (DTF1) and 3 (DTF3) that contribute to earlier flowering in the domesticated line under both photoperiods. The domesticated allele at a fourth locus on chromosome 6 (DTF6) delays flowering under long days only. Map positions, inheritance patterns, and expression analyses in near-isogenic comparisons imply that DTF1, DTF3, and DTF6 represent gain-of-function alleles of the florigen/antiflorigen genes FTa3, FTa1, and TFL1c/LF, respectively. This echoes similar variation in chickpea and lentil, and suggests a conserved route to reduced photoperiod sensitivity and early phenology in temperate pulses.
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Affiliation(s)
- Owen Williams
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, TAS 7001, Australia
| | | | - Jakob B Butler
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, TAS 7001, Australia
| | - Stephen Ridge
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, TAS 7001, Australia
| | - Frances C Sussmilch
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, TAS 7001, Australia
| | - Valerie F G Hecht
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, TAS 7001, Australia
| | - James L Weller
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, TAS 7001, Australia
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Rajandran V, Ortega R, Vander Schoor JK, Butler JB, Freeman JS, Hecht VFG, Erskine W, Murfet IC, Bett KE, Weller JL. Genetic analysis of early phenology in lentil identifies distinct loci controlling component traits. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:3963-3977. [PMID: 35290451 PMCID: PMC9238442 DOI: 10.1093/jxb/erac107] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Accepted: 03/11/2022] [Indexed: 05/25/2023]
Abstract
Modern-day domesticated lentil germplasm is generally considered to form three broad adaptation groups: Mediterranean, South Asian, and northern temperate, which correspond to the major global production environments. Reproductive phenology plays a key role in lentil adaptation to this diverse ecogeographic variation. Here, we dissect the characteristic earliness of the pilosae ecotype, suited to the typically short cropping season of South Asian environments. We identified two loci, DTF6a and DTF6b, at which dominant alleles confer early flowering, and we show that DTF6a alone is sufficient to confer early flowering under extremely short photoperiods. Genomic synteny confirmed the presence of a conserved cluster of three florigen (FT) gene orthologues among potential candidate genes, and expression analysis in near-isogenic material showed that the early allele is associated with a strong derepression of the FTa1 gene in particular. Sequence analysis revealed a 7.4 kb deletion in the FTa1-FTa2 intergenic region in the pilosae parent, and a wide survey of >350 accessions with diverse origin showed that the dtf6a allele is predominant in South Asian material. Collectively, these results contribute to understanding the molecular basis of global adaptation in lentil, and further emphasize the importance of this conserved genomic region for adaptation in temperate legumes generally.
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Affiliation(s)
- Vinodan Rajandran
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, TAS 7001, Australia
| | - Raul Ortega
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, TAS 7001, Australia
| | | | - Jakob B Butler
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, TAS 7001, Australia
| | - Jules S Freeman
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, TAS 7001, Australia
- Forest Genetics and Biotechnology, Scion, Private Bag 3020, Rotorua 3046, New Zealand
| | - Valerie F G Hecht
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, TAS 7001, Australia
| | - Willie Erskine
- School of Agriculture and Environment and Institute of Agriculture, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Ian C Murfet
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, TAS 7001, Australia
| | - Kirstin E Bett
- Department of Plant Sciences, University of Saskatchewan, Saskatoon, SK, S7N 5A8, Canada
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Nguyen DT, Hayes JE, Atieno J, Li Y, Baumann U, Pattison A, Bramley H, Hobson K, Roorkiwal M, Varshney RK, Colmer TD, Sutton T. The genetics of vigour-related traits in chickpea (Cicer arietinum L.): insights from genomic data. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2022; 135:107-124. [PMID: 34643761 DOI: 10.1007/s00122-021-03954-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 09/17/2021] [Indexed: 05/27/2023]
Abstract
QTL controlling vigour and related traits were identified in a chickpea RIL population and validated in diverse sets of germplasm. Robust KASP markers were developed for marker-assisted selection. To understand the genetic constitution of vigour in chickpea (Cicer arietinum L.), genomic data from a bi-parental population and multiple diversity panels were used to identify QTL, sequence-level haplotypes and genetic markers associated with vigour-related traits in Australian environments. Using 182 Recombinant Inbred Lines (RILs) derived from a cross between two desi varieties, Rupali and Genesis836, vigour QTL independent of flowering time were identified on chromosomes (Ca) 1, 3 and 4 with genotypic variance explained (GVE) ranging from 7.1 to 28.8%. Haplotype analysis, association analysis and graphical genotyping of whole-genome re-sequencing data of two diversity panels consisting of Australian and Indian genotypes and an ICRISAT Chickpea Reference Set revealed a deletion in the FTa1-FTa2-FTc gene cluster of Ca3 significantly associated with vigour and flowering time. Across the RIL population and diversity panels, the impact of the deletion was consistent for vigour but not flowering time. Vigour-related QTL on Ca4 co-located with a QTL for seed size in Rupali/Genesis836 (GVE = 61.3%). Using SNPs from this region, we developed and validated gene-based KASP markers across different panels. Two markers were developed for a gene on Ca1, myo -inositol monophosphatase (CaIMP), previously proposed to control seed size, seed germination and seedling growth in chickpea. While associated with vigour in the diversity panels, neither the markers nor broader haplotype linked to CaIMP was polymorphic in Rupali/Genesis836. Importantly, vigour appears to be controlled by different sets of QTL across time and with components which are independent from phenology.
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Affiliation(s)
- Duong T Nguyen
- School of Agriculture and Environment and UWA Institute of Agriculture, The University of Western Australia, 35 Stirling Highway, Crawley, WA, Australia
- South Australian Research and Development Institute, Hartley Grove, Urrbrae, SA, Australia
| | - Julie E Hayes
- School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Urrbrae, SA, Australia
| | - Judith Atieno
- South Australian Research and Development Institute, Hartley Grove, Urrbrae, SA, Australia
- School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Urrbrae, SA, Australia
| | - Yongle Li
- School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Urrbrae, SA, Australia
| | - Ute Baumann
- School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Urrbrae, SA, Australia
| | - Angela Pattison
- School of Life and Environmental Science, The University of Sydney, Camperdown, NSW, Australia
| | - Helen Bramley
- School of Life and Environmental Science, The University of Sydney, Camperdown, NSW, Australia
| | - Kristy Hobson
- Department of Primary Industries, Tamworth Agricultural Institute, 4 Marsden, Park Rd, Calala, NSW, Australia
| | - Manish Roorkiwal
- Centre of Excellence in Genomics and Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, 502324, India
| | - Rajeev K Varshney
- Centre of Excellence in Genomics and Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, 502324, India
- State Agricultural Biotechnology Centre, Centre for Crop and Food Innovation, Food Futures Institute, Murdoch University, Murdoch, WA, Australia
| | - Timothy D Colmer
- School of Agriculture and Environment and UWA Institute of Agriculture, The University of Western Australia, 35 Stirling Highway, Crawley, WA, Australia
| | - Tim Sutton
- South Australian Research and Development Institute, Hartley Grove, Urrbrae, SA, Australia.
- School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Urrbrae, SA, Australia.
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11
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Sun Q, Huang R, Zhu H, Sun Y, Guo Z. A novel Medicago truncatula calmodulin-like protein (MtCML42) regulates cold tolerance and flowering time. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 108:1069-1082. [PMID: 34528312 DOI: 10.1111/tpj.15494] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Revised: 09/02/2021] [Accepted: 09/09/2021] [Indexed: 05/20/2023]
Abstract
Calmodulin-like proteins (CMLs) are one of the Ca2+ sensors in plants, but the functions of most CMLs remain unknown. The regulation of cold tolerance and flowering time by MtCML42 in Medicago truncatula and the underlying mechanisms were investigated using MtCML42-overexpressing plants and cml42 Medicago mutants with a Tnt1 retrotransposon insertion. Compared with the wild type (WT), MtCML42-overexpressing lines had increased cold tolerance, whereas cml42 mutants showed decreased cold tolerance. The impaired cold tolerance in cml42 could b complemented by MtCML42 expression. The transcript levels of MtCBF1, MtCBF4, MtCOR413, MtCAS15, MtLTI6A, MtGolS1 and MtGolS2 and the concentrations of raffinose and sucrose were increased in response to cold treatment, whereas higher levels were observed in MtCML42-overexpressing lines and lower levels were observed in cml42 mutants. In addition, early flowering with upregulated MtFTa1 and downregulated MtABI5 transcripts was observed in MtCML42-overexpressing lines, whereas delayed flowering with downregulated MtFTa1 and upregulated MtABI5 was observed in cml42. MtABI5 expression could complement the flowering phenotype in the Arabidopsis mutant abi5. Our results suggest that MtCML42 positively regulates MtCBF1 and MtCBF4 expression, which in turn upregulates the expression of some COR genes, MtGolS1 and MtGolS2, which leads to raffinose accumulation and increased cold tolerance. MtCML42 regulates flowering time through sequentially downregulating MtABI5 and upregulating MtFTa1 expression.
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Affiliation(s)
- Qiguo Sun
- College of Grassland Science, Nanjing Agricultural University, Nanjing, 210095, China
| | - Risheng Huang
- College of Grassland Science, Nanjing Agricultural University, Nanjing, 210095, China
| | - Haifeng Zhu
- College of Grassland Science, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yanmei Sun
- College of Grassland Science, Nanjing Agricultural University, Nanjing, 210095, China
| | - Zhenfei Guo
- College of Grassland Science, Nanjing Agricultural University, Nanjing, 210095, China
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12
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Taylor CM, Garg G, Berger JD, Ribalta FM, Croser JS, Singh KB, Cowling WA, Kamphuis LG, Nelson MN. A Trimethylguanosine Synthase1-like (TGS1) homologue is implicated in vernalisation and flowering time control. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2021; 134:3411-3426. [PMID: 34258645 PMCID: PMC8440268 DOI: 10.1007/s00122-021-03910-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 07/06/2021] [Indexed: 05/30/2023]
Abstract
KEY MESSAGE A plant-specific Trimethylguanosine Synthase1-like homologue was identified as a candidate gene for the efl mutation in narrow-leafed lupin, which alters phenology by reducing vernalisation requirement. The vernalisation pathway is a key component of flowering time control in plants from temperate regions but is not well understood in the legume family. Here we examined vernalisation control in the temperate grain legume species, narrow-leafed lupin (Lupinus angustifolius L.), and discovered a candidate gene for an ethylene imine mutation (efl). The efl mutation changes phenology from late to mid-season flowering and additionally causes transformation from obligate to facultative vernalisation requirement. The efl locus was mapped to pseudochromosome NLL-10 in a recombinant inbred line (RIL) mapping population developed by accelerated single seed descent. Candidate genes were identified in the reference genome, and a diverse panel of narrow-leafed lupins was screened to validate mutations specific to accessions with efl. A non-synonymous SNP mutation within an S-adenosyl-L-methionine-dependent methyltransferase protein domain of a Trimethylguanosine Synthase1-like (TGS1) orthologue was identified as the candidate mutation giving rise to efl. This mutation caused substitution of an amino acid within an established motif at a position that is otherwise highly conserved in several plant families and was perfectly correlated with the efl phenotype in F2 and F6 genetic population and a panel of diverse accessions, including the original efl mutant. Expression of the TGS1 homologue did not differ between wild-type and efl genotypes, supporting altered functional activity of the gene product. This is the first time a TGS1 orthologue has been associated with vernalisation response and flowering time control in any plant species.
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Affiliation(s)
- Candy M Taylor
- UWA School of Agriculture and Environment, The University of Western Australia, Perth, WA, 6009, Australia
- The UWA Institute of Agriculture, The University of Western Australia, Perth, WA, 6009, Australia
| | - Gagan Garg
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Floreat, WA, 6014, Australia
| | - Jens D Berger
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Floreat, WA, 6014, Australia
| | - Federico M Ribalta
- UWA School of Agriculture and Environment, The University of Western Australia, Perth, WA, 6009, Australia
| | - Janine S Croser
- UWA School of Agriculture and Environment, The University of Western Australia, Perth, WA, 6009, Australia
- The UWA Institute of Agriculture, The University of Western Australia, Perth, WA, 6009, Australia
| | - Karam B Singh
- The UWA Institute of Agriculture, The University of Western Australia, Perth, WA, 6009, Australia
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Floreat, WA, 6014, Australia
- Centre for Crop and Disease Management, Curtin University, Bentley, WA, 6102, Australia
| | - Wallace A Cowling
- UWA School of Agriculture and Environment, The University of Western Australia, Perth, WA, 6009, Australia.
- The UWA Institute of Agriculture, The University of Western Australia, Perth, WA, 6009, Australia.
| | - Lars G Kamphuis
- The UWA Institute of Agriculture, The University of Western Australia, Perth, WA, 6009, Australia
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Floreat, WA, 6014, Australia
- Centre for Crop and Disease Management, Curtin University, Bentley, WA, 6102, Australia
| | - Matthew N Nelson
- The UWA Institute of Agriculture, The University of Western Australia, Perth, WA, 6009, Australia
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Floreat, WA, 6014, Australia
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13
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Zhang P, Liu H, Mysore KS, Wen J, Meng Y, Lin H, Niu L. MtFDa is essential for flowering control and inflorescence development in Medicago truncatula. JOURNAL OF PLANT PHYSIOLOGY 2021; 260:153412. [PMID: 33845341 DOI: 10.1016/j.jplph.2021.153412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 03/28/2021] [Accepted: 03/28/2021] [Indexed: 06/12/2023]
Abstract
Flowering plants display a vast diversity of flowering time and inflorescence architecture, which plays an important role in determining seed yield and fruit production. However, the molecular mechanism underlying the flowering control and compound inflorescence development, especially in legumes, remain to be elucidated. Here, we reported the identification of MtFDa, an essential regulator of flowering in the model legume Medicago truncatula. Mutation of MtFDa, led to the late flowering, abnormal secondary inflorescences as well as severe floral organ defects. Biochemical and molecular analyses revealed that MtFDa physically interacts with M. truncaula FLOWERING LOCUS T homolog, MtFTa1, a key regulator of Medicago flowering time, and this interaction facilitates MtFDa's function in activating the expression of MtSOC1a. Moreover, we demonstrated that MtFDa may affect secondary inflorescence development via regulating MtFULc expression in M. truncatula. Our findings help elucidate the mechanism of MtFDa-mediated regulation of flowering time and inflorescence development and provide insights into understanding the genetic regulatory network underlying complex productive development in legumes.
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Affiliation(s)
- Pengcheng Zhang
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Huan Liu
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | | | - Jiangqi Wen
- Noble Research Institute, Ardmore, OK, 73401, USA
| | - Yingying Meng
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Hao Lin
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Lifang Niu
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
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14
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Cullerne DP, Fjellheim S, Spriggs A, Eamens AL, Trevaskis B, Wood CC. A Vernalization Response in a Winter Safflower ( Carthamus tinctorius) Involves the Upregulation of Homologs of FT, FUL, and MAF. FRONTIERS IN PLANT SCIENCE 2021; 12:639014. [PMID: 33859660 PMCID: PMC8043130 DOI: 10.3389/fpls.2021.639014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 02/24/2021] [Indexed: 05/28/2023]
Abstract
Safflower (Carthamus tinctorius) is a member of the Asteraceae family that is grown in temperate climates as an oil seed crop. Most commercially grown safflower varieties can be sown in late winter or early spring and flower rapidly in the absence of overwintering. There are winter-hardy safflower accessions that can be sown in autumn and survive over-wintering. Here, we show that a winter-hardy safflower possesses a vernalization response, whereby flowering is accelerated by exposing germinating seeds to prolonged cold. The impact of vernalization was quantitative, such that increasing the duration of cold treatment accelerated flowering to a greater extent, until the response was saturated after 2 weeks exposure to low-temperatures. To investigate the molecular-basis of the vernalization-response in safflower, transcriptome activity was compared and contrasted between vernalized versus non-vernalized plants, in both 'winter hardy' and 'spring' cultivars. These genome-wide expression analyses identified a small set of transcripts that are both differentially expressed following vernalization and that also have different expression levels in the spring versus winter safflowers. Four of these transcripts were quantitatively induced by vernalization in a winter hardy safflower but show high basal levels in spring safflower. Phylogenetic analyses confidently assigned that the nucleotide sequences of the four differentially expressed transcripts are related to FLOWERING LOCUS T (FT), FRUITFUL (FUL), and two genes within the MADS-like clade genes. Gene models were built for each of these sequences by assembling an improved safflower reference genome using PacBio-based long-read sequencing, covering 85% of the genome, with N50 at 594,000 bp in 3000 contigs. Possible evolutionary relationships between the vernalization response of safflower and those of other plants are discussed.
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Affiliation(s)
- Darren P. Cullerne
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Canberra, ACT, Australia
| | - Siri Fjellheim
- Department of Plant Sciences, Norwegian University of Life Sciences, Ås, Norway
| | - Andrew Spriggs
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Canberra, ACT, Australia
| | - Andrew L. Eamens
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW, Australia
| | - Ben Trevaskis
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Canberra, ACT, Australia
| | - Craig C. Wood
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Canberra, ACT, Australia
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15
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Cheng X, Li G, Krom N, Tang Y, Wen J. Genetic regulation of flowering time and inflorescence architecture by MtFDa and MtFTa1 in Medicago truncatula. PLANT PHYSIOLOGY 2021; 185:161-178. [PMID: 33631796 PMCID: PMC8133602 DOI: 10.1093/plphys/kiaa005] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 10/11/2020] [Indexed: 05/29/2023]
Abstract
Regulation of floral transition and inflorescence development is crucial for plant reproductive success. FLOWERING LOCUS T (FT) is one of the central players in the flowering genetic regulatory network, whereas FLOWERING LOCUS D (FD), an interactor of FT and TERMINAL FLOWER 1 (TFL1), plays significant roles in both floral transition and inflorescence development. Here we show the genetic regulatory networks of floral transition and inflorescence development in Medicago truncatula by characterizing MtFTa1 and MtFDa and their genetic interactions with key inflorescence meristem (IM) regulators. Both MtFTa1 and MtFDa promote flowering; the double mutant mtfda mtfta1 does not proceed to floral transition. RNAseq analysis reveals that a broad range of genes involved in flowering regulation and flower development are up- or downregulated by MtFTa1 and/or MtFDa mutations. Furthermore, mutation of MtFDa also affects the inflorescence architecture. Genetic analyses of MtFDa, MtFTa1, MtTFL1, and MtFULc show that MtFDa is epistatic to MtFULc and MtTFL1 in controlling IM identity. Our results demonstrate that MtFTa1 and MtFDa are major flowering regulators in M. truncatula, and MtFDa is essential both in floral transition and secondary inflorescence development. The study will advance our understanding of the genetic regulation of flowering time and inflorescence development in legumes.
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Affiliation(s)
- Xiaofei Cheng
- Noble Research Institute, Ardmore, Oklahoma 73401, USA
| | - Guifen Li
- Noble Research Institute, Ardmore, Oklahoma 73401, USA
| | - Nick Krom
- Noble Research Institute, Ardmore, Oklahoma 73401, USA
| | - Yuhong Tang
- Noble Research Institute, Ardmore, Oklahoma 73401, USA
| | - Jiangqi Wen
- Noble Research Institute, Ardmore, Oklahoma 73401, USA
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16
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Thomson G, Zhang L, Wen J, Mysore KS, Putterill J. The Candidate Photoperiod Gene MtFE Promotes Growth and Flowering in Medicago truncatula. FRONTIERS IN PLANT SCIENCE 2021; 12:634091. [PMID: 33841463 PMCID: PMC8032900 DOI: 10.3389/fpls.2021.634091] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 03/01/2021] [Indexed: 05/04/2023]
Abstract
Flowering time influences the yield and productivity of legume crops. Medicago truncatula is a reference temperate legume that, like the winter annual Arabidopsis thaliana, shows accelerated flowering in response to vernalization (extended cold) and long-day (LD) photoperiods (VLD). However, unlike A. thaliana, M. truncatula appears to lack functional homologs of core flowering time regulators CONSTANS (CO) and FLOWERING LOCUS C (FLC) which act upstream of the mobile florigen FLOWERING LOCUS T (FT). Medicago truncatula has three LD-induced FT-like genes (MtFTa1, MtFTb1, and MtFTb2) with MtFTa1 promoting M. truncatula flowering in response to VLD. Another photoperiodic regulator in A. thaliana, FE, acts to induce FT expression. It also regulates the FT transport pathway and is required for phloem development. Our study identifies a M. truncatula FE homolog Medtr6g444980 (MtFE) which complements the late flowering fe-1 mutant when expressed from the phloem-specific SUCROSE-PROTON SYMPORTER 2 (SUC2) promoter. Analysis of two M. truncatula Tnt1 insertional mutants indicate that MtFE promotes flowering in LD and VLD and growth in all conditions tested. Expression of MtFTa1, MtFTb1, and MtFTb2 are reduced in Mtfe mutant (NF5076), correlating with its delayed flowering. The NF5076 mutant plants are much smaller than wild type indicating that MtFE is important for normal plant growth. The second mutant (NF18291) displays seedling lethality, like strong fe mutants. We searched for mutants in MtFTb1 and MtFTb2 identifying a Mtftb2 knock out Tnt1 mutant (NF20803). However, it did not flower significantly later than wild type. Previously, yeast-two-hybrid assays (Y2H) suggested that Arabidopsis FE interacted with CO and NUCLEAR FACTOR-Y (NF-Y)-like proteins to regulate FT. We found that MtFE interacts with CO and also M. truncatula NF-Y-like proteins in Y2H experiments. Our study indicates that despite the apparent absence of a functional MtCO-like gene, M. truncatula FE likely influences photoperiodic FT expression and flowering time in M. truncatula via a partially conserved mechanism with A. thaliana.
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Affiliation(s)
- Geoffrey Thomson
- The Flowering Lab, School of Biological Sciences, University of Auckland, Auckland, New Zealand
- *Correspondence: Geoffrey Thomson, ;
| | - Lulu Zhang
- The Flowering Lab, School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Jiangqi Wen
- Noble Research Institute, Ardmore, OK, United States
| | | | - Joanna Putterill
- The Flowering Lab, School of Biological Sciences, University of Auckland, Auckland, New Zealand
- *Correspondence: Geoffrey Thomson, ;
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17
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Yuan S, Li Z, Yuan N, Hu Q, Zhou M, Zhao J, Li D, Luo H. MiR396 is involved in plant response to vernalization and flower development in Agrostis stolonifera. HORTICULTURE RESEARCH 2020; 7:173. [PMID: 33328434 PMCID: PMC7603517 DOI: 10.1038/s41438-020-00394-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Revised: 08/23/2020] [Accepted: 08/30/2020] [Indexed: 05/05/2023]
Abstract
MicroRNA396 (miR396) has been demonstrated to regulate flower development by targeting growth-regulating factors (GRFs) in annual species. However, its role in perennial grasses and its potential involvement in flowering time control remain unexplored. Here we report that overexpression of miR396 in a perennial species, creeping bentgrass (Agrostis stolonifera L.), alters flower development. Most significantly, transgenic (TG) plants bypass the vernalization requirement for flowering. Gene expression analysis reveals that miR396 is induced by long-day (LD) photoperiod and vernalization. Further study identifies VRN1, VRN2, and VRN3 homologs whose expression patterns in wild-type (WT) plants are similar to those observed in wheat and barley during transition from short-day (SD) to LD, and SD to cold conditions. However, compared to WT controls, TG plants overexpressing miR396 exhibit significantly enhanced VRN1 and VRN3 expression, but repressed VRN2 expression under SD to LD conditions without vernalization, which might be associated with modified expression of methyltransferase genes. Collectively, our results unveil a potentially novel mechanism by which miR396 suppresses the vernalization requirement for flowering which might be related to the epigenetic regulation of VRN genes and provide important new insight into critical roles of a miRNA in regulating vernalization-mediated transition from vegetative to reproductive growth in monocots.
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Affiliation(s)
- Shuangrong Yuan
- Department of Genetics and Biochemistry, Clemson University, 110 Biosystems Research Complex, Clemson, SC, 29634, USA
| | - Zhigang Li
- Department of Genetics and Biochemistry, Clemson University, 110 Biosystems Research Complex, Clemson, SC, 29634, USA
| | - Ning Yuan
- Department of Genetics and Biochemistry, Clemson University, 110 Biosystems Research Complex, Clemson, SC, 29634, USA
| | - Qian Hu
- Department of Genetics and Biochemistry, Clemson University, 110 Biosystems Research Complex, Clemson, SC, 29634, USA
| | - Man Zhou
- Department of Genetics and Biochemistry, Clemson University, 110 Biosystems Research Complex, Clemson, SC, 29634, USA
| | - Junming Zhao
- Department of Genetics and Biochemistry, Clemson University, 110 Biosystems Research Complex, Clemson, SC, 29634, USA
- Department of Grassland Science, Sichuan Agricultural University, 611130, Chengdu, Sichuan, China
| | - Dayong Li
- Department of Genetics and Biochemistry, Clemson University, 110 Biosystems Research Complex, Clemson, SC, 29634, USA
- Beijing Vegetable Research Center, Beijing Academy of Agriculture and forestry Science, 100097, Beijing, China
| | - Hong Luo
- Department of Genetics and Biochemistry, Clemson University, 110 Biosystems Research Complex, Clemson, SC, 29634, USA.
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18
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Jaudal M, Wen J, Mysore KS, Putterill J. Medicago PHYA promotes flowering, primary stem elongation and expression of flowering time genes in long days. BMC PLANT BIOLOGY 2020; 20:329. [PMID: 32652925 PMCID: PMC7353751 DOI: 10.1186/s12870-020-02540-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 07/05/2020] [Indexed: 05/04/2023]
Abstract
BACKGROUND Flowering time is an important trait for productivity in legumes, which include many food and fodder plants. Medicago truncatula (Medicago) is a model temperate legume used to study flowering time pathways. Like Arabidopsis thaliana (Arabidopsis), its flowering is promoted by extended periods of cold (vernalization, V), followed by warm long day (LD) photoperiods. However, Arabidopsis flowering-time genes such as the FLOWERING LOCUS C (FLC)/ MADS AFFECTING FLOWERING (MAF) clade are missing and CONSTANS-LIKE (CO-LIKE) genes do not appear to have a role in Medicago or Pisum sativum (pea). Another photoperiodic regulator, the red/far red photoreceptor PHYTOCHROME A (PHYA), promotes Arabidopsis flowering by stabilizing the CO protein in LD. Interestingly, despite the absence of CO-LIKE function in pea, PsPHYA plays a key role in promoting LD photoperiodic flowering and plant architecture. Medicago has one homolog of PHYA, MtPHYA, but its function is not known. RESULTS Genetic analysis of two MtPHYA Tnt1 insertion mutant alleles indicates that MtPHYA has an important role in promoting Medicago flowering and primary stem elongation in VLD and LD and in perception of far-red wavelengths in seedlings. MtPHYA positively regulates the expression of MtE1-like (MtE1L), a homologue of an important legume-specific flowering time gene, E1 in soybean and other Medicago LD-regulated flowering-time gene homologues, including the three FLOWERING LOCUS T-LIKE (FT-LIKE) genes, MtFTa1, MtFTb1 and MtFTb2 and the two FRUITFULL-LIKE (FUL-LIKE) genes MtFULa and MtFULb. MtPHYA also modulates the expression of the circadian clock genes, GIGANTEA (GI) and TIMING OF CAB EXPRESSION 1a (TOC1a). Genetic analyses indicate that Mtphya-1 Mte1l double mutants flowered at the same time as the single mutants. However, Mtphya-1 Mtfta1 double mutants had a weak additive effect in delaying flowering and in reduction of primary axis lengths beyond what was conferred by either of the single mutants. CONCLUSION MtPHYA has an important role in LD photoperiodic control of flowering, plant architecture and seedling de-etiolation under far-red wavelengths in Medicago. It promotes the expression of LD-induced flowering time genes and modulates clock-related genes. In addition to MtFTa1, MtPHYA likely regulates other targets during LD floral induction in Medicago.
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Affiliation(s)
- Mauren Jaudal
- The Flowering Lab, School of Biological Sciences, University of Auckland, Auckland, New Zealand.
| | - Jiangqi Wen
- Noble Research Institute, 2510 Sam Noble Parkway, Ardmore, OK73401, USA
| | | | - Joanna Putterill
- The Flowering Lab, School of Biological Sciences, University of Auckland, Auckland, New Zealand.
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19
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Zhou J, Liu L, Li Q, Xu W, Li K, Wang ZW, Sun Q. Intronic heterochromatin prevents cryptic transcription initiation in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 101:1185-1197. [PMID: 31647592 DOI: 10.1111/tpj.14584] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 10/06/2019] [Accepted: 10/17/2019] [Indexed: 06/10/2023]
Abstract
Intronic transposable elements (TEs) comprise a large proportion in eukaryotic genomes, but how they regulate the host genes remains to be explored. Our forward genetic screen disclosed the plant-specific RNA polymerases IV and V in suppressing intronic TE-mediated cryptic transcription initiation of a chimeric transcripts at FLC (FLCTE ). Initiation of FLCTE transcription is blocked by the locally formed intronic heterochromatin, which is directly associated with RNA Pol V to inhibit the entry of RNA Pol II and the occupancy of H3K4 methylation. Genome-wide Pol II Ser5p native elongation transcription sequencing revealed that a significant number of intronic heterochromatin-containing genes undergo this mechanism. This study sheds light on deeply understanding the function of intronic heterochromatin on host genes expression in eukaryotic genome.
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Affiliation(s)
- Jincong Zhou
- Tsinghua-Peking Joint Center for Life Sciences and Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Liangyu Liu
- Key Laboratory of Plant Gene Resources and Biotechnology for Carbon Reduction and Environmental Improvement, Beijing Municipal Government, College of Life Sciences, Capital Normal University, Beijing, China
| | - Qin Li
- Tsinghua-Peking Joint Center for Life Sciences and Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Wei Xu
- Tsinghua-Peking Joint Center for Life Sciences and Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Kuan Li
- Tsinghua-Peking Joint Center for Life Sciences and Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Zhi-Wei Wang
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, College of Tropical Agriculture and Forestry, Hainan University, Haikou, China
| | - Qianwen Sun
- Tsinghua-Peking Joint Center for Life Sciences and Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
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20
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Ortega R, Hecht VFG, Freeman JS, Rubio J, Carrasquilla-Garcia N, Mir RR, Penmetsa RV, Cook DR, Millan T, Weller JL. Altered Expression of an FT Cluster Underlies a Major Locus Controlling Domestication-Related Changes to Chickpea Phenology and Growth Habit. FRONTIERS IN PLANT SCIENCE 2019; 10:824. [PMID: 31333691 PMCID: PMC6616154 DOI: 10.3389/fpls.2019.00824] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 06/07/2019] [Indexed: 05/20/2023]
Abstract
Flowering time is a key trait in breeding and crop evolution, due to its importance for adaptation to different environments and for yield. In the particular case of chickpea, selection for early phenology was essential for the successful transition of this species from a winter to a summer crop. Here, we used genetic and expression analyses in two different inbred populations to examine the genetic control of domestication-related differences in flowering time and growth habit between domesticated chickpea and its wild progenitor Cicer reticulatum. A single major quantitative trait locus for flowering time under short-day conditions [Days To Flower (DTF)3A] was mapped to a 59-gene interval on chromosome three containing a cluster of three FT genes, which collectively showed upregulated expression in domesticated relative to wild parent lines. An equally strong association with growth habit suggests a pleiotropic effect of the region on both traits. These results indicate the likely molecular explanation for the characteristic early flowering of domesticated chickpea, and the previously described growth habit locus Hg. More generally, they point to de-repression of this specific gene cluster as a conserved mechanism for achieving adaptive early phenology in temperate legumes.
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Affiliation(s)
- Raul Ortega
- School of Natural Sciences, University of Tasmania, Hobart, TAS, Australia
| | | | - Jules S. Freeman
- School of Natural Sciences, University of Tasmania, Hobart, TAS, Australia
- Scion, Rotorua, New Zealand
| | - Josefa Rubio
- E. Genomica y Biotecnologia, Instituto Andaluz de Investigación y Formación Agraria y Pesquera (IFAPA), Córdoba, Spain
| | | | - Reyazul Rouf Mir
- Department of Plant Pathology, University of California, Davis, Davis, CA, United States
- Division of Genetics and Plant Breeding, Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir, Srinagar, India
| | - R. Varma Penmetsa
- Department of Plant Pathology, University of California, Davis, Davis, CA, United States
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Douglas R. Cook
- Department of Plant Pathology, University of California, Davis, Davis, CA, United States
| | - Teresa Millan
- Department of Genetics ETSIAM, University of Córdoba, Córdoba, Spain
| | - James L. Weller
- School of Natural Sciences, University of Tasmania, Hobart, TAS, Australia
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21
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Kang J, Zhang T, Guo T, Ding W, Long R, Yang Q, Wang Z. Isolation and Functional Characterization of MsFTa, a FLOWERING LOCUS T Homolog from Alfalfa ( Medicago sativa). Int J Mol Sci 2019; 20:ijms20081968. [PMID: 31013631 PMCID: PMC6514984 DOI: 10.3390/ijms20081968] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Revised: 03/18/2019] [Accepted: 04/15/2019] [Indexed: 01/16/2023] Open
Abstract
The production of hay and seeds of alfalfa, an important legume forage for the diary industry worldwide, is highly related to flowering time, which has been widely reported to be integrated by FLOWERING LOCUS T (FT). However, the function of FT(s) in alfalfa is largely unknown. Here, we identified MsFTa, an FT ortholog in alfalfa, and characterized its role in flowering regulation. MsFTa shares the conserved exon/intron structure of FTs, and the deduced MsFTa is 98% identical to MtFTa1 in Medicago trucatula. MsFTa was diurnally regulated with a peak before the dark period, and was preferentially expressed in leaves and floral buds. Transient expression of MsFTa-GFP fusion protein demonstrated its localization in the nucleus and cytoplasm. When ectopically expressed, MsFTa rescued the late-flowering phenotype of ft mutants from Arabidopsis and M. trucatula. MsFTa over-expression plants of both Arabidopsis and M. truncatula flowered significantly earlier than the non-transgenic controls under long day conditions, indicating that exogenous MsFTa strongly accelerated flowering. Hence, MsFTa functions positively in flowering promotion, suggesting that MsFTa may encode a florigen that acts as a key regulator in the flowering pathway. This study provides an effective candidate gene for optimizing alfalfa flowering time by genetically manipulating the expression of MsFTa.
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Affiliation(s)
- Junmei Kang
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
| | - Tiejun Zhang
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
| | - Tao Guo
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
| | - Wang Ding
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
| | - Ruicai Long
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
| | - Qingchuan Yang
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
| | - Zhen Wang
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
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22
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Taylor CM, Kamphuis LG, Zhang W, Garg G, Berger JD, Mousavi‐Derazmahalleh M, Bayer PE, Edwards D, Singh KB, Cowling WA, Nelson MN. INDEL variation in the regulatory region of the major flowering time gene LanFTc1 is associated with vernalization response and flowering time in narrow-leafed lupin (Lupinus angustifolius L.). PLANT, CELL & ENVIRONMENT 2019; 42:174-187. [PMID: 29677403 PMCID: PMC7379684 DOI: 10.1111/pce.13320] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 04/09/2018] [Accepted: 04/09/2018] [Indexed: 05/02/2023]
Abstract
Narrow-leafed lupin (Lupinus angustifolius L.) cultivation was transformed by 2 dominant vernalization-insensitive, early flowering time loci known as Ku and Julius (Jul), which allowed expansion into shorter season environments. However, reliance on these loci has limited genetic and phenotypic diversity for environmental adaptation in cultivated lupin. We recently predicted that a 1,423-bp deletion in the cis-regulatory region of LanFTc1, a FLOWERING LOCUS T (FT) homologue, derepressed expression of LanFTc1 and was the underlying cause of the Ku phenotype. Here, we surveyed diverse germplasm for LanFTc1 cis-regulatory variation and identified 2 further deletions of 1,208 and 5,162 bp in the 5' regulatory region, which overlap the 1,423-bp deletion. Additionally, we confirmed that no other polymorphisms were perfectly associated with vernalization responsiveness. Phenotyping and gene expression analyses revealed that Jul accessions possessed the 5,162-bp deletion and that the Jul and Ku deletions were equally capable of removing vernalization requirement and up-regulating gene expression. The 1,208-bp deletion was associated with intermediate phenology, vernalization responsiveness, and gene expression and therefore may be useful for expanding agronomic adaptation of lupin. This insertion/deletion series may also help resolve how the vernalization response is mediated at the molecular level in legumes.
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Affiliation(s)
- Candy M. Taylor
- UWA School of Agriculture and EnvironmentThe University of Western AustraliaPerthWestern Australia6009Australia
| | - Lars G. Kamphuis
- Agriculture and FoodCommonwealth Scientific and Industrial Research OrganisationFloreatWestern Australia6014Australia
- Centre for Crop and Disease ManagementCurtin UniversityBentleyWestern Australia6102Australia
- The UWA Institute of AgricultureThe University of Western AustraliaPerthWestern Australia6009Australia
| | - Weilu Zhang
- UWA School of Agriculture and EnvironmentThe University of Western AustraliaPerthWestern Australia6009Australia
| | - Gagan Garg
- Agriculture and FoodCommonwealth Scientific and Industrial Research OrganisationFloreatWestern Australia6014Australia
| | - Jens D. Berger
- Agriculture and FoodCommonwealth Scientific and Industrial Research OrganisationFloreatWestern Australia6014Australia
| | - Mahsa Mousavi‐Derazmahalleh
- UWA School of Agriculture and EnvironmentThe University of Western AustraliaPerthWestern Australia6009Australia
| | - Philipp E. Bayer
- School of Biological SciencesThe University of Western AustraliaPerthWestern Australia6009Australia
| | - David Edwards
- School of Biological SciencesThe University of Western AustraliaPerthWestern Australia6009Australia
- The UWA Institute of AgricultureThe University of Western AustraliaPerthWestern Australia6009Australia
| | - Karam B. Singh
- Agriculture and FoodCommonwealth Scientific and Industrial Research OrganisationFloreatWestern Australia6014Australia
- Centre for Crop and Disease ManagementCurtin UniversityBentleyWestern Australia6102Australia
- The UWA Institute of AgricultureThe University of Western AustraliaPerthWestern Australia6009Australia
| | - Wallace A. Cowling
- UWA School of Agriculture and EnvironmentThe University of Western AustraliaPerthWestern Australia6009Australia
- The UWA Institute of AgricultureThe University of Western AustraliaPerthWestern Australia6009Australia
| | - Matthew N. Nelson
- UWA School of Agriculture and EnvironmentThe University of Western AustraliaPerthWestern Australia6009Australia
- The UWA Institute of AgricultureThe University of Western AustraliaPerthWestern Australia6009Australia
- Natural Capital and Plant HealthRoyal Botanic Gardens, KewArdinglyWest SussexRH17 6TNUK
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23
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Jaudal M, Zhang L, Che C, Li G, Tang Y, Wen J, Mysore KS, Putterill J. A SOC1-like gene MtSOC1a promotes flowering and primary stem elongation in Medicago. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:4867-4880. [PMID: 30295903 PMCID: PMC6137972 DOI: 10.1093/jxb/ery284] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 07/10/2018] [Indexed: 05/19/2023]
Abstract
Medicago flowering, like that of Arabidopsis, is promoted by vernalization and long days, but alternative mechanisms are predicted because Medicago lacks the key regulators CO and FLC. Three Medicago SOC1-like genes, including MtSOC1a, were previously implicated in flowering control, but no legume soc1 mutants with altered flowering were reported. Here, reverse transciption-quantitative PCR (RT-qPCR) indicated that the timing and magnitude of MtSOC1a expression was regulated by the flowering promoter FTa1, while in situ hybridization indicated that MtSOC1a expression increased in the shoot apical meristem during the floral transition. A Mtsoc1a mutant showed delayed flowering and short primary stems. Overexpression of MtSOC1a partially rescued the flowering of Mtsoc1a, but caused a dramatic increase in primary stem height, well before the transition to flowering. Internode cell length correlated with stem height, indicating that MtSOC1a promotes cell elongation in the primary stem. However, application of gibberellin (GA3) caused stem elongation in both the wild type and Mtsoc1a, indicating that the mutant was not defective in gibberellin responsiveness. These results indicate that MtSOC1a may function as a floral integrator gene and promotes primary stem elongation. Overall, this study suggests that apart from some conservation with the Arabidopsis flowering network, MtSOC1a has a novel role in regulating aspects of shoot architecture.
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Affiliation(s)
- Mauren Jaudal
- Flowering Lab, School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Lulu Zhang
- Flowering Lab, School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Chong Che
- Flowering Lab, School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Guifen Li
- Noble Research Institute, LLC, Ardmore, OK, USA
| | - Yuhong Tang
- Noble Research Institute, LLC, Ardmore, OK, USA
| | - Jiangqi Wen
- Noble Research Institute, LLC, Ardmore, OK, USA
| | | | - Joanna Putterill
- Flowering Lab, School of Biological Sciences, University of Auckland, Auckland, New Zealand
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24
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Functional Genomics and Flowering Time in Medicago truncatula: An Overview. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2018; 1822:261-271. [PMID: 30043309 DOI: 10.1007/978-1-4939-8633-0_17] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Flowering time is an important trait that influences adaptation and yield in many crop legumes. Both the inherent earliness of flowering and the degree to which it is responsive to environmental factors determine both the eco-geographic range across which crops can be successfully grown and the seasonal cycles most suitable for production. This chapter will provide a brief review of studies investigating the genetic control of flowering time in Medicago truncatula.
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25
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Fudge JB, Lee RH, Laurie RE, Mysore KS, Wen J, Weller JL, Macknight RC. Medicago truncatula SOC1 Genes Are Up-regulated by Environmental Cues That Promote Flowering. FRONTIERS IN PLANT SCIENCE 2018; 9:496. [PMID: 29755488 PMCID: PMC5934494 DOI: 10.3389/fpls.2018.00496] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Accepted: 04/03/2018] [Indexed: 05/20/2023]
Abstract
Like Arabidopsis thaliana, the flowering of the legume Medicago truncatula is promoted by long day (LD) photoperiod and vernalization. However, there are differences in the molecular mechanisms involved, with orthologs of two key Arabidopsis thaliana regulators, FLOWERING LOCUS C (FLC) and CONSTANS (CO), being absent or not having a role in flowering time function in Medicago. In Arabidopsis, the MADS-box transcription factor gene, SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (AtSOC1), plays a key role in integrating the photoperiodic and vernalization pathways. In this study, we set out to investigate whether the Medicago SOC1 genes play a role in regulating flowering time. Three Medicago SOC1 genes were identified and characterized (MtSOC1a-MtSOC1c). All three MtSOC1 genes, when heterologously expressed, were able to promote earlier flowering of the late-flowering Arabidopsis soc1-2 mutant. The three MtSOC1 genes have different patterns of expression. However, consistent with a potential role in flowering time regulation, all three MtSOC1 genes are expressed in the shoot apex and are up-regulated in the shoot apex of plants in response to LD photoperiods and vernalization. The up-regulation of MtSOC1 genes was reduced in Medicago fta1-1 mutants, indicating that they are downstream of MtFTa1. Insertion mutant alleles of Medicago soc1b do not flower late, suggestive of functional redundancy among Medicago SOC1 genes in promoting flowering.
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Affiliation(s)
- Jared B. Fudge
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Robyn H. Lee
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Rebecca E. Laurie
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Kirankumar S. Mysore
- Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, OK, United States
| | - Jiangqi Wen
- Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, OK, United States
| | - James L. Weller
- School of Biological Sciences, University of Tasmania, Hobart, TAS, Australia
| | - Richard C. Macknight
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
- New Zealand Institute for Plant and Food Research Ltd., University of Otago, Dunedin, New Zealand
- *Correspondence: Richard C. Macknight,
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26
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Garmier M, Gentzbittel L, Wen J, Mysore KS, Ratet P. Medicago truncatula: Genetic and Genomic Resources. ACTA ACUST UNITED AC 2017; 2:318-349. [PMID: 33383982 DOI: 10.1002/cppb.20058] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Medicago truncatula was chosen by the legume community, along with Lotus japonicus, as a model plant to study legume biology. Since then, numerous resources and tools have been developed for M. truncatula. These include, for example, its genome sequence, core ecotype collections, transformation/regeneration methods, extensive mutant collections, and a gene expression atlas. This review aims to describe the different genetic and genomic tools and resources currently available for M. truncatula. We also describe how these resources were generated and provide all the information necessary to access these resources and use them from a practical point of view. © 2017 by John Wiley & Sons, Inc.
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Affiliation(s)
- Marie Garmier
- Institute of Plant Sciences Paris-Saclay, Centre National de la Recherche Scientifique, Institut National de Recherche Agronomique, Université Paris-Sud, Université Evry, Université Paris-Saclay, Orsay, France.,Institute of Plant Sciences Paris-Saclay, Université Paris Diderot, Université Sorbonne Paris-Cité, Orsay, France
| | - Laurent Gentzbittel
- EcoLab, Université de Toulouse, Centre National de la Recherche Scientifique, Institut National Polytechnique de Toulouse, Université Paul Sabatier, Castanet-Tolosan, France
| | | | | | - Pascal Ratet
- Institute of Plant Sciences Paris-Saclay, Centre National de la Recherche Scientifique, Institut National de Recherche Agronomique, Université Paris-Sud, Université Evry, Université Paris-Saclay, Orsay, France.,Institute of Plant Sciences Paris-Saclay, Université Paris Diderot, Université Sorbonne Paris-Cité, Orsay, France
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27
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Nelson MN, Książkiewicz M, Rychel S, Besharat N, Taylor CM, Wyrwa K, Jost R, Erskine W, Cowling WA, Berger JD, Batley J, Weller JL, Naganowska B, Wolko B. The loss of vernalization requirement in narrow-leafed lupin is associated with a deletion in the promoter and de-repressed expression of a Flowering Locus T (FT) homologue. THE NEW PHYTOLOGIST 2017; 213:220-232. [PMID: 27418400 DOI: 10.1111/nph.14094] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 06/05/2016] [Indexed: 05/19/2023]
Abstract
Adaptation of Lupinus angustifolius (narrow-leafed lupin) to cropping in southern Australian and northern Europe was transformed by a dominant mutation (Ku) that removed vernalization requirement for flowering. The Ku mutation is now widely used in lupin breeding to confer early flowering and maturity. We report here the identity of the Ku mutation. We used a range of genetic, genomic and gene expression approaches to determine whether Flowering Locus T (FT) homologues are associated with the Ku locus. One of four FT homologues present in the narrow-leafed lupin genome, LanFTc1, perfectly co-segregated with the Ku locus in a reference mapping population. Expression of LanFTc1 in the ku (late-flowering) parent was strongly induced by vernalization, in contrast to the Ku (early-flowering) parent, which showed constitutively high LanFTc1 expression. Co-segregation of this expression phenotype with the LanFTc1 genotype indicated that the Ku mutation impairs cis-regulation of LanFTc1. Sequencing of LanFTc1 revealed a 1.4-kb deletion in the promoter region, which was perfectly predictive of vernalization response in 216 wild and domesticated accessions. Linkage disequilibrium rapidly decayed around LanFTc1, suggesting that this deletion caused the loss of vernalization response. This is the first time a legume FTc subclade gene has been implicated in the vernalization response.
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Affiliation(s)
- Matthew N Nelson
- Natural Capital and Plant Health, Royal Botanic Gardens Kew, Wakehurst Place, Ardingly, West Sussex, RH17 6TN, UK
- School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Perth, WA, 6009, Australia
- The UWA Institute of Agriculture, The University of Western Australia, 35 Stirling Highway, Perth, WA, 6009, Australia
| | - Michał Książkiewicz
- Institute of Plant Genetics, Polish Academy of Sciences, Strzeszyńska 34, 60-479, Poznań, Poland
| | - Sandra Rychel
- Institute of Plant Genetics, Polish Academy of Sciences, Strzeszyńska 34, 60-479, Poznań, Poland
| | - Naghmeh Besharat
- School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Perth, WA, 6009, Australia
| | - Candy M Taylor
- School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Perth, WA, 6009, Australia
| | - Katarzyna Wyrwa
- Institute of Plant Genetics, Polish Academy of Sciences, Strzeszyńska 34, 60-479, Poznań, Poland
| | - Ricarda Jost
- School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Perth, WA, 6009, Australia
- Australian Research Council Centre of Excellence in Plant Energy Biology and Centre for AgriBiosciences, Department of Animal, Plant and Soil Science, School of Life Science, La Trobe University, 5 Ring Road, Bundoora, Victoria, 3083, Australia
| | - William Erskine
- The UWA Institute of Agriculture, The University of Western Australia, 35 Stirling Highway, Perth, WA, 6009, Australia
- Centre for Plant Genetics and Breeding, School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia
| | - Wallace A Cowling
- The UWA Institute of Agriculture, The University of Western Australia, 35 Stirling Highway, Perth, WA, 6009, Australia
| | - Jens D Berger
- Centre for Plant Genetics and Breeding, School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia
- CSIRO Agriculture, Private Bag No. 5, Wembley, WA, 6913, Australia
| | - Jacqueline Batley
- School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Perth, WA, 6009, Australia
- The UWA Institute of Agriculture, The University of Western Australia, 35 Stirling Highway, Perth, WA, 6009, Australia
| | - James L Weller
- School of Biological Sciences, University of Tasmania, Hobart, Tasmania, 7001, Australia
| | - Barbara Naganowska
- Institute of Plant Genetics, Polish Academy of Sciences, Strzeszyńska 34, 60-479, Poznań, Poland
| | - Bogdan Wolko
- Institute of Plant Genetics, Polish Academy of Sciences, Strzeszyńska 34, 60-479, Poznań, Poland
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28
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Jaudal M, Zhang L, Che C, Hurley DG, Thomson G, Wen J, Mysore KS, Putterill J. MtVRN2 is a Polycomb VRN2-like gene which represses the transition to flowering in the model legume Medicago truncatula. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2016; 86:145-60. [PMID: 26947149 DOI: 10.1111/tpj.13156] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 02/24/2016] [Accepted: 02/29/2016] [Indexed: 05/02/2023]
Abstract
Optimising the timing of flowering contributes to successful sexual reproduction and yield in agricultural plants. FLOWERING LOCUS T (FT) genes, first identified in Arabidopsis thaliana (Arabidopsis), promote flowering universally, but the upstream flowering regulatory pathways can differ markedly among plants. Flowering in the model legume, Medicago truncatula (Medicago) is accelerated by winter cold (vernalisation) followed by long day (LD) photoperiods leading to elevated expression of the floral activator, FT-like gene FTa1. However, Medicago, like some other plants, lacks the activator CONSTANS (CO) and the repressor FLOWERING LOCUS C (FLC) genes which directly regulate FT and are key to LD and vernalisation responses in Arabidopsis. Conversely, Medicago has a VERNALISATION2-LIKE VEFS-box gene (MtVRN2). In Arabidopsis AtVRN2 is a key member of a Polycomb complex involved in stable repression of Arabidopsis FLC after vernalisation. VRN2-like genes have been identified in other eudicot plants, but their function has never been reported. We show that Mtvrn2 mutants bypass the need for vernalisation for early flowering in LD conditions in Medicago. Investigation of the underlying mechanism by transcriptome analysis reveals that Mtvrn2 mutants precociously express FTa1 and other suites of genes including floral homeotic genes. Double-mutant analysis indicates that early flowering is dependent on functional FTa1. The broad significance of our study is that we have demonstrated a function for a VRN2-like VEFS gene beyond the Brassicaceae. In particular, MtVRN2 represses the transition to flowering in Medicago by regulating the onset of expression of the potent floral activator, FTa1.
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Affiliation(s)
- Mauren Jaudal
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Lulu Zhang
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Chong Che
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Daniel G Hurley
- Systems Biology Laboratory, Electrical and Electronic Engineering, Melbourne School of Engineering, Melbourne, Australia
- Centre for Systems Genomics, University of Melbourne, Melbourne, Australia
| | - Geoffrey Thomson
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Jiangqi Wen
- Samuel Roberts Noble Foundation, Ardmore, Oklahoma, USA
| | | | - Joanna Putterill
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
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29
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The Hairless Stem Phenotype of Cotton (Gossypium barbadense) Is Linked to a Copia-Like Retrotransposon Insertion in a Homeodomain-Leucine Zipper Gene (HD1). Genetics 2015; 201:143-54. [PMID: 26133897 DOI: 10.1534/genetics.115.178236] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Accepted: 06/25/2015] [Indexed: 02/03/2023] Open
Abstract
Cotton (Gossypium) stem trichomes are mostly single cells that arise from stem epidermal cells. In this study, a homeodomain-leucine zipper gene (HD1) was found to cosegregate with the dominant trichome locus previously designated as T1 and mapped to chromosome 6. Characterization of HD1 orthologs revealed that the absence of stem trichomes in modern Gossypium barbadense varieties is linked to a large retrotransposon insertion in the ninth exon, 2565 bp downstream from the initial codon in the At subgenome HD1 gene (At-GbHD1). In both the At and Dt subgenomes, reduced transcription of GbHD1 genes is caused by this insertion. The disruption of At-HD1 further affects the expression of downstream GbMYB25 and GbHOX3 genes. Analyses of primitive cultivated accessions identified another retrotransposon insertion event in the sixth exon of At-GbHD1 that might predate the previously identified retrotransposon in modern varieties. Although both retrotransposon insertions results in similar phenotypic changes, the timing of these two retrotransposon insertion events fits well with our current understanding of the history of cotton speciation and dispersal. Taken together, the results of genetics mapping, gene expression and association analyses suggest that GbHD1 is an important component that controls stem trichome development and is a promising candidate gene for the T1 locus. The interspecific phenotypic difference in stem trichome traits also may be attributable to HD1 inactivation associated with retrotransposon insertion.
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30
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Jaudal M, Zhang L, Che C, Putterill J. Three Medicago MtFUL genes have distinct and overlapping expression patterns during vegetative and reproductive development and 35S:MtFULb accelerates flowering and causes a terminal flower phenotype in Arabidopsis. Front Genet 2015; 6:50. [PMID: 25745430 PMCID: PMC4333866 DOI: 10.3389/fgene.2015.00050] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 01/02/2015] [Indexed: 11/13/2022] Open
Abstract
The timing of the transition to flowering is carefully controlled by plants in order to optimize sexual reproduction and the ensuing production of seeds, grains, and fruits. The genetic networks that regulate floral induction are best characterized in the temperate eudicot Arabidopsis in which the florigen gene FT plays a major role in promoting the transition to flowering. Legumes are an important plant group, but less is known about the regulation of their flowering time. In the model legume Medicago truncatula (Medicago), a temperate annual plant like Arabidopsis, flowering is induced by prolonged cold (vernalization) followed by long day lengths (LD). Recent molecular-genetic experiments have revealed that a FT-like gene, MtFTa1, is a central regulator of flowering time in Medicago. Here, we characterize the three Medicago FRUITFULL (FUL) MADS transcription factors, MtFULa, MtFULb, and MtFULc using phylogenetic analyses, gene expression profiling through developmental time courses, and functional analyses in transgenic plants. MtFULa and MtFULb have similarity in sequence and expression profiles under inductive environmental conditions during both vegetative and reproductive development while MtFULc is only up regulated in the apex after flowering in LD conditions. Sustained up regulation of MtFULs requires functional MtFTa1 but their transcript levels are not affected during cold treatment. Overexpression of MtFULa and MtFULb promotes flowering in transgenic Arabidopsis plants with an additional terminal flower phenotype on some 35S:MtFULb plants. An increase in transcript levels of the MtFULs was also observed in Medicago plants overexpressing MtFTa1. Our results suggest that the MtFULs are targets of MtFTa1. Overall, this work highlights the conserved functions of FUL-like genes in promoting flowering and other roles in plant development and thus contributes to our understanding of the genetic control of the flowering process in Medicago.
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Affiliation(s)
| | | | | | - Joanna Putterill
- The Flowering Lab, School of Biological Sciences, University of AucklandAuckland, New Zealand
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Weller JL, Ortega R. Genetic control of flowering time in legumes. FRONTIERS IN PLANT SCIENCE 2015; 6:207. [PMID: 25914700 PMCID: PMC4391241 DOI: 10.3389/fpls.2015.00207] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 03/15/2015] [Indexed: 05/18/2023]
Abstract
The timing of flowering, and in particular the degree to which it is responsive to the environment, is a key factor in the adaptation of a given species to various eco-geographic locations and agricultural practices. Flowering time variation has been documented in many crop legumes, and selection for specific variants has permitted significant expansion and improvement in cultivation, from prehistoric times to the present day. Recent advances in legume genomics have accelerated the process of gene identification and functional analysis, and opened up new prospects for a molecular understanding of flowering time adaptation in this important crop group. Within the legumes, two species have been prominent in flowering time studies; the vernalization-responsive long-day species pea (Pisum sativum) and the warm-season short-day plant soybean (Glycine max). Analysis of flowering in these species is now being complemented by reverse genetics capabilities in the model legumes Medicago truncatula and Lotus japonicus, and the emergence of genome-scale resources in a range of other legumes. This review will outline the insights gained from detailed forward genetic analysis of flowering time in pea and soybean, highlighting the importance of light perception, the circadian clock and the FT family of flowering integrators. It discusses the current state of knowledge on genetic mechanisms for photoperiod and vernalization response, and concludes with a broader discussion of flowering time adaptation across legumes generally.
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Affiliation(s)
- James L. Weller
- *Correspondence: James L. Weller, School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, TAS 7001, Australia
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Romera-Branchat M, Andrés F, Coupland G. Flowering responses to seasonal cues: what's new? CURRENT OPINION IN PLANT BIOLOGY 2014; 21:120-127. [PMID: 25072635 DOI: 10.1016/j.pbi.2014.07.006] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 06/30/2014] [Accepted: 07/07/2014] [Indexed: 05/20/2023]
Abstract
Seasonal cues of day length or winter cold trigger flowering of many species. Forward and reverse genetic approaches are revealing the mechanisms by which these responses are conferred. Homologues of the Arabidopsis thaliana protein FLOWERING LOCUS T (FT) are widely used to mediate seasonal responses to day length and act as graft-transmissible promoters or repressors of flowering. Winter cold in A. thaliana promotes flowering by repressing transcription of the MADS box gene FLOWERING LOCUS C (FLC). The mechanism by which this occurs involves a complex interplay of different forms of long noncoding RNAs induced at the FLC locus during cold and changes in the chromatin of FLC. In perennial relatives of A. thaliana, flowering also requires the age-dependent downregulation of miRNA156 before winter.
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Affiliation(s)
| | - Fernando Andrés
- Max Planck Institute for Plant Breeding Research, D-50829 Cologne, Germany
| | - George Coupland
- Max Planck Institute for Plant Breeding Research, D-50829 Cologne, Germany.
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Liew LC, Singh MB, Bhalla PL. Unique and conserved features of floral evocation in legumes. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2014; 56:714-728. [PMID: 24930396 DOI: 10.1111/jipb.12187] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Accepted: 02/19/2014] [Indexed: 06/03/2023]
Abstract
Legumes, with their unique ability to fix atmospheric nitrogen, play a vital role in ensuring future food security and mitigating the effects of climate change because they use less fossil energy and produce less greenhouse gases compared with N-fertilized systems. Grain legumes are second only to cereal crops as a source of human and animal food, and they contribute approximately one third of the protein consumed by the human population. The productivity of seed crops, such as grain legumes, is dependent on flowering. Despite the genetic variation and importance of flowering in legume production, studies of the molecular pathways that control flowering in legumes are limited. Recent advances in genomics have revealed that legume flowering pathways are divergent from those of such model species as Arabidopsis thaliana. Here, we discuss the current understanding of flowering time regulation in legumes and highlight the unique and conserved features of floral evocation in legumes.
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Affiliation(s)
- Lim Chee Liew
- Plant Molecular Biology and Biotechnology Laboratory, Melbourne School of Land and Environment, University of Melbourne, Parkville, Victoria, 3010, Australia
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Franklin KA, Toledo-Ortiz G, Pyott DE, Halliday KJ. Interaction of light and temperature signalling. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:2859-71. [PMID: 24569036 DOI: 10.1093/jxb/eru059] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Light and temperature are arguably two of the most important signals regulating the growth and development of plants. In addition to their direct energetic effects on plant growth, light and temperature provide vital immediate and predictive cues for plants to ensure optimal development both spatially and temporally. While the majority of research to date has focused on the contribution of either light or temperature signals in isolation, it is becoming apparent that an understanding of how the two interact is essential to appreciate fully the complex and elegant ways in which plants utilize these environmental cues. This review will outline the diverse mechanisms by which light and temperature signals are integrated and will consider why such interconnected systems (as opposed to entirely separate light and temperature pathways) may be evolutionarily favourable.
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Affiliation(s)
- Keara A Franklin
- School of Biological Sciences, University of Bristol, Bristol BS8 1UG, UK
| | - Gabriela Toledo-Ortiz
- SynthSys, University of Edinburgh, C.H. Waddington Building, King's Buildings, Edinburgh EH9 3JD, UK
| | - Douglas E Pyott
- SynthSys, University of Edinburgh, C.H. Waddington Building, King's Buildings, Edinburgh EH9 3JD, UK
| | - Karen J Halliday
- SynthSys, University of Edinburgh, C.H. Waddington Building, King's Buildings, Edinburgh EH9 3JD, UK
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Veerappan V, Kadel K, Alexis N, Scott A, Kryvoruchko I, Sinharoy S, Taylor M, Udvardi M, Dickstein R. Keel petal incision: a simple and efficient method for genetic crossing in Medicago truncatula. PLANT METHODS 2014; 10:11. [PMID: 24966878 PMCID: PMC4070640 DOI: 10.1186/1746-4811-10-11] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 03/17/2014] [Indexed: 05/11/2023]
Abstract
BACKGROUND Genetic crossing is an essential tool in both forward and reverse genetic approaches to understand the biological functions of genes. For Medicago truncatula (barrel medic) various crossing techniques have been used which differ in the methods used to dissect the female parent's unopened flower bud to remove immature anthers for prevention of self-pollination. Previously described methods including front, side or back incision methods may damage the flower bud, impeding successful fertilization and/or seed development because they may allow pollen to dislodge and floral organs to desiccate after crossing, all of which diminish the success rates of crossing. RESULTS We report the keel petal incision method for genetic crossing in M. truncatula ecotype R108 and demonstrate successful crosses with two other M. truncatula ecotypes, A17 and A20. In the method presented here, an incision is made along the central line of the keel petal from the bottom 1/3rd of the female parent's flower bud to its distal end. This allows easy removal of anthers from the flower bud and access for cross-pollination. After pollination, the stigma and the deposited pollen from the male donor are covered by the keel petal, wing petals and standard petal, forming a natural pouch. The pouch prevents dislodging of deposited pollen from the stigma and protects the internal floral organs from drying out, without using cling-film or water-containing chambers to maintain a humid environment. The keel petal incision method showed an approximate 80% success rate in the M. truncatula R108 ecotype and also in other ecotypes including Jemalong A17 and A20. CONCLUSIONS Our keel petal incision protocol shows marked improvement over existing methods with respect to the ease of crossing and the percentage of successful crosses. Developed for the M. truncatula R108 ecotype, the protocol has been demonstrated with A17 and A20 ecotypes and is expected to work with other ecotypes. Investigators of varying experience have achieved genetic crosses in M. truncatula using this method.
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Affiliation(s)
- Vijaykumar Veerappan
- Department of Biological Sciences, University of North Texas, 1155 Union Circle #305220, Denton, Texas 76203, USA
| | - Khem Kadel
- Department of Biological Sciences, University of North Texas, 1155 Union Circle #305220, Denton, Texas 76203, USA
| | - Naudin Alexis
- Department of Biological Sciences, University of North Texas, 1155 Union Circle #305220, Denton, Texas 76203, USA
| | - Ashley Scott
- Department of Biological Sciences, University of North Texas, 1155 Union Circle #305220, Denton, Texas 76203, USA
| | - Igor Kryvoruchko
- Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA
| | - Senjuti Sinharoy
- Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA
| | - Mark Taylor
- Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA
| | - Michael Udvardi
- Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA
| | - Rebecca Dickstein
- Department of Biological Sciences, University of North Texas, 1155 Union Circle #305220, Denton, Texas 76203, USA
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