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Acharya BR, Gill SP, Kaundal A, Sandhu D. Strategies for combating plant salinity stress: the potential of plant growth-promoting microorganisms. FRONTIERS IN PLANT SCIENCE 2024; 15:1406913. [PMID: 39077513 PMCID: PMC11284086 DOI: 10.3389/fpls.2024.1406913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Accepted: 06/24/2024] [Indexed: 07/31/2024]
Abstract
Global climate change and the decreasing availability of high-quality water lead to an increase in the salinization of agricultural lands. This rising salinity represents a significant abiotic stressor that detrimentally influences plant physiology and gene expression. Consequently, critical processes such as seed germination, growth, development, and yield are adversely affected. Salinity severely impacts crop yields, given that many crop plants are sensitive to salt stress. Plant growth-promoting microorganisms (PGPMs) in the rhizosphere or the rhizoplane of plants are considered the "second genome" of plants as they contribute significantly to improving the plant growth and fitness of plants under normal conditions and when plants are under stress such as salinity. PGPMs are crucial in assisting plants to navigate the harsh conditions imposed by salt stress. By enhancing water and nutrient absorption, which is often hampered by high salinity, these microorganisms significantly improve plant resilience. They bolster the plant's defenses by increasing the production of osmoprotectants and antioxidants, mitigating salt-induced damage. Furthermore, PGPMs supply growth-promoting hormones like auxins and gibberellins and reduce levels of the stress hormone ethylene, fostering healthier plant growth. Importantly, they activate genes responsible for maintaining ion balance, a vital aspect of plant survival in saline environments. This review underscores the multifaceted roles of PGPMs in supporting plant life under salt stress, highlighting their value for agriculture in salt-affected areas and their potential impact on global food security.
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Affiliation(s)
- Biswa R. Acharya
- US Salinity Laboratory, USDA-ARS, Riverside, CA, United States
- College of Natural and Agricultural Sciences, University of California Riverside, Riverside, CA, United States
| | - Satwinder Pal Gill
- Plants, Soils, and Climate, College of Agricultural and Applied Sciences, Utah State University, Logan, UT, United States
| | - Amita Kaundal
- Plants, Soils, and Climate, College of Agricultural and Applied Sciences, Utah State University, Logan, UT, United States
| | - Devinder Sandhu
- US Salinity Laboratory, USDA-ARS, Riverside, CA, United States
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2
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Gal A, Dalal A, Anfang M, Sharma D, Binenbaum J, Muchaki P, Kumar R, Egbaria A, Duarte KE, Kelly G, de Souza WR, Sade N. Plasma membrane aquaporins regulate root hydraulic conductivity in the model plant Setaria viridis. PLANT PHYSIOLOGY 2023; 193:2640-2660. [PMID: 37607257 DOI: 10.1093/plphys/kiad469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 07/26/2023] [Accepted: 08/02/2023] [Indexed: 08/24/2023]
Abstract
The high rate of productivity observed in panicoid crops is in part due to their extensive root system. Recently, green foxtail (Setaria viridis) has emerged as a genetic model system for panicoid grasses. Natural accessions of S. viridis originating from different parts of the world, with differential leaf physiological behavior, have been identified. This work focused on understanding the physiological and molecular mechanisms controlling root hydraulic conductivity and root-to-shoot gas exchange signaling in S. viridis. We identified 2 accessions, SHA and ZHA, with contrasting behavior at the leaf, root, and whole-plant levels. Our results indicated a role for root aquaporin (AQP) plasma membrane (PM) intrinsic proteins in the differential behavior of SHA and ZHA. Moreover, a different root hydraulic response to low levels of abscisic acid between SHA and ZHA was observed, which was associated with root AQPs. Using cell imaging, biochemical, and reverse genetic approaches, we identified PM intrinsic protein 1;6 (PIP1;6) as a possible PIP1 candidate that regulates radial root hydraulics and root-to-shoot signaling of gas exchange in S. viridis. In heterologous systems, PIP1;6 localized in the endoplasmic reticulum, and upon interaction with PIP2s, relocalization to the PM was observed. PIP1;6 was predominantly expressed at the root endodermis. Generation of knockout PIP1;6 plants (KO-PIP1;6) in S. viridis showed altered root hydraulic conductivity, altered gas exchange, and alteration of root transcriptional patterns. Our results indicate that PIPs are essential in regulating whole-plant water homeostasis in S. viridis. We conclude that root hydraulic conductivity and gas exchange are positively associated and are regulated by AQPs.
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Affiliation(s)
- Atara Gal
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ahan Dalal
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv 69978, Israel
| | - Moran Anfang
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv 69978, Israel
| | - Davinder Sharma
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv 69978, Israel
| | - Jenia Binenbaum
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv 69978, Israel
| | - Purity Muchaki
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv 69978, Israel
| | - Rakesh Kumar
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv 69978, Israel
| | - Aiman Egbaria
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv 69978, Israel
| | - Karoline Estefani Duarte
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC (UFABC), Santo André 09210170, Brazil
| | - Gilor Kelly
- The Volcani Center, Institute of Plant Sciences, Agricultural Research Organization, Rishon Le-Zion 7505101, Israel
| | - Wagner Rodrigo de Souza
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC (UFABC), Santo André 09210170, Brazil
| | - Nir Sade
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv 69978, Israel
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3
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Liu Q, Teng S, Deng C, Wu S, Li H, Wang Y, Wu J, Cui X, Zhang Z, Quick WP, Brutnell TP, Sun X, Lu T. SHORT ROOT and INDETERMINATE DOMAIN family members govern PIN-FORMED expression to regulate minor vein differentiation in rice. THE PLANT CELL 2023; 35:2848-2870. [PMID: 37154077 PMCID: PMC10396363 DOI: 10.1093/plcell/koad125] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 03/08/2023] [Accepted: 04/02/2023] [Indexed: 05/10/2023]
Abstract
C3 and C4 grasses directly and indirectly provide the vast majority of calories to the human diet, yet our understanding of the molecular mechanisms driving photosynthetic productivity in grasses is largely unexplored. Ground meristem cells divide to form mesophyll or vascular initial cells early in leaf development in C3 and C4 grasses. Here we define a genetic circuit composed of SHORT ROOT (SHR), INDETERMINATE DOMAIN (IDD), and PIN-FORMED (PIN) family members that specifies vascular identify and ground cell proliferation in leaves of both C3 and C4 grasses. Ectopic expression and loss-of-function mutant studies of SHR paralogs in the C3 plant Oryza sativa (rice) and the C4 plant Setaria viridis (green millet) revealed the roles of these genes in both minor vein formation and ground cell differentiation. Genetic and in vitro studies further suggested that SHR regulates this process through its interactions with IDD12 and 13. We also revealed direct interactions of these IDD proteins with a putative regulatory element within the auxin transporter gene PIN5c. Collectively, these findings indicate that a SHR-IDD regulatory circuit mediates auxin transport by negatively regulating PIN expression to modulate minor vein patterning in the grasses.
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Affiliation(s)
- Qiming Liu
- Biotechnology Research Institute (BRI), Chinese Academy of Agricultural Sciences (CAAS), Beijing 100081, China
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
| | - Shouzhen Teng
- Biotechnology Research Institute (BRI), Chinese Academy of Agricultural Sciences (CAAS), Beijing 100081, China
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
| | - Chen Deng
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
| | - Suting Wu
- Biotechnology Research Institute (BRI), Chinese Academy of Agricultural Sciences (CAAS), Beijing 100081, China
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
| | - Haoshu Li
- Biotechnology Research Institute (BRI), Chinese Academy of Agricultural Sciences (CAAS), Beijing 100081, China
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
| | - Yanwei Wang
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
| | - Jinxia Wu
- Biotechnology Research Institute (BRI), Chinese Academy of Agricultural Sciences (CAAS), Beijing 100081, China
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
| | - Xuean Cui
- Biotechnology Research Institute (BRI), Chinese Academy of Agricultural Sciences (CAAS), Beijing 100081, China
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
| | - Zhiguo Zhang
- Biotechnology Research Institute (BRI), Chinese Academy of Agricultural Sciences (CAAS), Beijing 100081, China
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
| | - William Paul Quick
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
- C4 Rice Centre, International Rice Research Institute, Los Banos, Laguna 4030, Philippines
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Thomas P Brutnell
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
| | - Xuehui Sun
- Biotechnology Research Institute (BRI), Chinese Academy of Agricultural Sciences (CAAS), Beijing 100081, China
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
| | - Tiegang Lu
- Biotechnology Research Institute (BRI), Chinese Academy of Agricultural Sciences (CAAS), Beijing 100081, China
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, BRI, CAAS, Beijing 100081, China
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Khodaeiaminjan M, Knoch D, Ndella Thiaw MR, Marchetti CF, Kořínková N, Techer A, Nguyen TD, Chu J, Bertholomey V, Doridant I, Gantet P, Graner A, Neumann K, Bergougnoux V. Genome-wide association study in two-row spring barley landraces identifies QTL associated with plantlets root system architecture traits in well-watered and osmotic stress conditions. FRONTIERS IN PLANT SCIENCE 2023; 14:1125672. [PMID: 37077626 PMCID: PMC10106628 DOI: 10.3389/fpls.2023.1125672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 03/15/2023] [Indexed: 05/03/2023]
Abstract
Water availability is undoubtedly one of the most important environmental factors affecting crop production. Drought causes a gradual deprivation of water in the soil from top to deep layers and can occur at diverse stages of plant development. Roots are the first organs that perceive water deficit in soil and their adaptive development contributes to drought adaptation. Domestication has contributed to a bottleneck in genetic diversity. Wild species or landraces represent a pool of genetic diversity that has not been exploited yet in breeding program. In this study, we used a collection of 230 two-row spring barley landraces to detect phenotypic variation in root system plasticity in response to drought and to identify new quantitative trait loci (QTL) involved in root system architecture under diverse growth conditions. For this purpose, young seedlings grown for 21 days in pouches under control and osmotic-stress conditions were phenotyped and genotyped using the barley 50k iSelect SNP array, and genome-wide association studies (GWAS) were conducted using three different GWAS methods (MLM GAPIT, FarmCPU, and BLINK) to detect genotype/phenotype associations. In total, 276 significant marker-trait associations (MTAs; p-value (FDR)< 0.05) were identified for root (14 and 12 traits under osmotic-stress and control conditions, respectively) and for three shoot traits under both conditions. In total, 52 QTL (multi-trait or identified by at least two different GWAS approaches) were investigated to identify genes representing promising candidates with a role in root development and adaptation to drought stress.
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Affiliation(s)
- Mortaza Khodaeiaminjan
- Czech Advanced Technology and Research Institute, Palacký University in Olomouc, Olomouc, Czechia
| | - Dominic Knoch
- Department of Molecular Genetics, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany
| | | | - Cintia F. Marchetti
- Czech Advanced Technology and Research Institute, Palacký University in Olomouc, Olomouc, Czechia
| | - Nikola Kořínková
- Czech Advanced Technology and Research Institute, Palacký University in Olomouc, Olomouc, Czechia
| | - Alexie Techer
- Czech Advanced Technology and Research Institute, Palacký University in Olomouc, Olomouc, Czechia
| | - Thu D. Nguyen
- Czech Advanced Technology and Research Institute, Palacký University in Olomouc, Olomouc, Czechia
| | - Jianting Chu
- Department of Breeding Research, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany
| | - Valentin Bertholomey
- Limagrain Field Seeds, Traits and Technologies, Groupe Limagrain Centre de Recherche, Chappes, France
| | - Ingrid Doridant
- Limagrain Field Seeds, Traits and Technologies, Groupe Limagrain Centre de Recherche, Chappes, France
| | - Pascal Gantet
- Czech Advanced Technology and Research Institute, Palacký University in Olomouc, Olomouc, Czechia
- Unité Mixte de Recherche DIADE, Université de Montpellier, IRD, CIRAD, Montpellier, France
| | - Andreas Graner
- Department Genebank, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany
| | - Kerstin Neumann
- Department of Molecular Genetics, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany
| | - Véronique Bergougnoux
- Czech Advanced Technology and Research Institute, Palacký University in Olomouc, Olomouc, Czechia
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5
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Langan P, Bernád V, Walsh J, Henchy J, Khodaeiaminjan M, Mangina E, Negrão S. Phenotyping for waterlogging tolerance in crops: current trends and future prospects. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:5149-5169. [PMID: 35642593 PMCID: PMC9440438 DOI: 10.1093/jxb/erac243] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 05/30/2022] [Indexed: 06/15/2023]
Abstract
Yield losses to waterlogging are expected to become an increasingly costly and frequent issue in some regions of the world. Despite the extensive work that has been carried out examining the molecular and physiological responses to waterlogging, phenotyping for waterlogging tolerance has proven difficult. This difficulty is largely due to the high variability of waterlogging conditions such as duration, temperature, soil type, and growth stage of the crop. In this review, we highlight use of phenotyping to assess and improve waterlogging tolerance in temperate crop species. We start by outlining the experimental methods that have been utilized to impose waterlogging stress, ranging from highly controlled conditions of hydroponic systems to large-scale screenings in the field. We also describe the phenotyping traits used to assess tolerance ranging from survival rates and visual scoring to precise photosynthetic measurements. Finally, we present an overview of the challenges faced in attempting to improve waterlogging tolerance, the trade-offs associated with phenotyping in controlled conditions, limitations of classic phenotyping methods, and future trends using plant-imaging methods. If effectively utilized to increase crop resilience to changing climates, crop phenotyping has a major role to play in global food security.
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Affiliation(s)
- Patrick Langan
- School of Biology and Environmental Science, University College Dublin, Dublin, Ireland
| | - Villő Bernád
- School of Biology and Environmental Science, University College Dublin, Dublin, Ireland
| | - Jason Walsh
- School of Biology and Environmental Science, University College Dublin, Dublin, Ireland
- School of Computer Science and UCD Energy Institute, University College Dublin, Dublin, Ireland
| | - Joey Henchy
- School of Biology and Environmental Science, University College Dublin, Dublin, Ireland
| | | | - Eleni Mangina
- School of Computer Science and UCD Energy Institute, University College Dublin, Dublin, Ireland
| | - Sónia Negrão
- School of Biology and Environmental Science, University College Dublin, Dublin, Ireland
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6
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Aggarwal PR, Pramitha L, Choudhary P, Singh RK, Shukla P, Prasad M, Muthamilarasan M. Multi-omics intervention in Setaria to dissect climate-resilient traits: Progress and prospects. FRONTIERS IN PLANT SCIENCE 2022; 13:892736. [PMID: 36119586 PMCID: PMC9470963 DOI: 10.3389/fpls.2022.892736] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 08/05/2022] [Indexed: 06/15/2023]
Abstract
Millets constitute a significant proportion of underutilized grasses and are well known for their climate resilience as well as excellent nutritional profiles. Among millets, foxtail millet (Setaria italica) and its wild relative green foxtail (S. viridis) are collectively regarded as models for studying broad-spectrum traits, including abiotic stress tolerance, C4 photosynthesis, biofuel, and nutritional traits. Since the genome sequence release, the crop has seen an exponential increase in omics studies to dissect agronomic, nutritional, biofuel, and climate-resilience traits. These studies have provided first-hand information on the structure, organization, evolution, and expression of several genes; however, knowledge of the precise roles of such genes and their products remains elusive. Several open-access databases have also been instituted to enable advanced scientific research on these important crops. In this context, the current review enumerates the contemporary trend of research on understanding the climate resilience and other essential traits in Setaria, the knowledge gap, and how the information could be translated for the crop improvement of related millets, biofuel crops, and cereals. Also, the review provides a roadmap for studying other underutilized crop species using Setaria as a model.
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Affiliation(s)
- Pooja Rani Aggarwal
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, Telangana, India
| | - Lydia Pramitha
- School of Agriculture and Biosciences, Karunya Institute of Technology and Sciences, Coimbatore, Tamil Nadu, India
| | - Pooja Choudhary
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, Telangana, India
| | | | - Pooja Shukla
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, Telangana, India
| | - Manoj Prasad
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, Telangana, India
- National Institute of Plant Genome Research (NIPGR), New Delhi, India
| | - Mehanathan Muthamilarasan
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, Telangana, India
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7
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Zhu C, Box MS, Thiruppathi D, Hu H, Yu Y, Martin C, Doust AN, McSteen P, Kellogg EA. Pleiotropic and nonredundant effects of an auxin importer in Setaria and maize. PLANT PHYSIOLOGY 2022; 189:715-734. [PMID: 35285930 DOI: 10.1101/2021.10.14.464408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 02/16/2022] [Indexed: 05/26/2023]
Abstract
Directional transport of auxin is critical for inflorescence and floral development in flowering plants, but the role of auxin influx carriers (AUX1 proteins) has been largely overlooked. Taking advantage of available AUX1 mutants in green millet (Setaria viridis) and maize (Zea mays), we uncover previously unreported aspects of plant development that are affected by auxin influx, including higher order branches in the inflorescence, stigma branch number, glume (floral bract) development, and plant fertility. However, disruption of auxin flux does not affect all parts of the plant, with little obvious effect on inflorescence meristem size, time to flowering, and anther morphology. In double mutant studies in maize, disruptions of ZmAUX1 also affect vegetative development. A green fluorescent protein (GFP)-tagged construct of the Setaria AUX1 protein Sparse Panicle1 (SPP1) under its native promoter showed that SPP1 localizes to the plasma membrane of outer tissue layers in both roots and inflorescences, and accumulates specifically in inflorescence branch meristems, consistent with the mutant phenotype and expected auxin maxima. RNA-seq analysis indicated that most gene expression modules are conserved between mutant and wild-type plants, with only a few hundred genes differentially expressed in spp1 inflorescences. Using clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 technology, we disrupted SPP1 and the other four AUX1 homologs in S. viridis. SPP1 has a larger effect on inflorescence development than the others, although all contribute to plant height, tiller formation, and leaf and root development. The AUX1 importers are thus not fully redundant in S. viridis. Our detailed phenotypic characterization plus a stable GFP-tagged line offer tools for future dissection of the function of auxin influx proteins.
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Affiliation(s)
- Chuanmei Zhu
- Donald Danforth Plant Science Center, St Louis, Missouri 63132, USA
| | - Mathew S Box
- Donald Danforth Plant Science Center, St Louis, Missouri 63132, USA
| | | | - Hao Hu
- Department of Plant Biology, Ecology, and Evolution, Oklahoma State University, Oklahoma 74078, USA
| | - Yunqing Yu
- Donald Danforth Plant Science Center, St Louis, Missouri 63132, USA
| | - Callista Martin
- Donald Danforth Plant Science Center, St Louis, Missouri 63132, USA
| | - Andrew N Doust
- Department of Plant Biology, Ecology, and Evolution, Oklahoma State University, Oklahoma 74078, USA
| | - Paula McSteen
- Division of Biological Sciences, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, Columbia, Missouri 65211, USA
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8
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Zhu C, Box MS, Thiruppathi D, Hu H, Yu Y, Martin C, Doust AN, McSteen P, Kellogg EA. Pleiotropic and nonredundant effects of an auxin importer in Setaria and maize. PLANT PHYSIOLOGY 2022; 189:715-734. [PMID: 35285930 PMCID: PMC9157071 DOI: 10.1093/plphys/kiac115] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 02/16/2022] [Indexed: 06/14/2023]
Abstract
Directional transport of auxin is critical for inflorescence and floral development in flowering plants, but the role of auxin influx carriers (AUX1 proteins) has been largely overlooked. Taking advantage of available AUX1 mutants in green millet (Setaria viridis) and maize (Zea mays), we uncover previously unreported aspects of plant development that are affected by auxin influx, including higher order branches in the inflorescence, stigma branch number, glume (floral bract) development, and plant fertility. However, disruption of auxin flux does not affect all parts of the plant, with little obvious effect on inflorescence meristem size, time to flowering, and anther morphology. In double mutant studies in maize, disruptions of ZmAUX1 also affect vegetative development. A green fluorescent protein (GFP)-tagged construct of the Setaria AUX1 protein Sparse Panicle1 (SPP1) under its native promoter showed that SPP1 localizes to the plasma membrane of outer tissue layers in both roots and inflorescences, and accumulates specifically in inflorescence branch meristems, consistent with the mutant phenotype and expected auxin maxima. RNA-seq analysis indicated that most gene expression modules are conserved between mutant and wild-type plants, with only a few hundred genes differentially expressed in spp1 inflorescences. Using clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 technology, we disrupted SPP1 and the other four AUX1 homologs in S. viridis. SPP1 has a larger effect on inflorescence development than the others, although all contribute to plant height, tiller formation, and leaf and root development. The AUX1 importers are thus not fully redundant in S. viridis. Our detailed phenotypic characterization plus a stable GFP-tagged line offer tools for future dissection of the function of auxin influx proteins.
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Affiliation(s)
- Chuanmei Zhu
- Donald Danforth Plant Science Center, St Louis, Missouri 63132, USA
| | - Mathew S Box
- Donald Danforth Plant Science Center, St Louis, Missouri 63132, USA
| | | | - Hao Hu
- Department of Plant Biology, Ecology, and Evolution, Oklahoma State University, Oklahoma 74078, USA
| | - Yunqing Yu
- Donald Danforth Plant Science Center, St Louis, Missouri 63132, USA
| | - Callista Martin
- Donald Danforth Plant Science Center, St Louis, Missouri 63132, USA
| | - Andrew N Doust
- Department of Plant Biology, Ecology, and Evolution, Oklahoma State University, Oklahoma 74078, USA
| | - Paula McSteen
- Division of Biological Sciences, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, Columbia, Missouri 65211, USA
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9
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Calace P, Tonetti T, Margarit E, Figueroa CM, Lobertti C, Andreo CS, Gerrard Wheeler MC, Saigo M. The C4 cycle and beyond: diverse metabolic adaptations accompany dual-cell photosynthetic functions in Setaria. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:7876-7890. [PMID: 34402880 DOI: 10.1093/jxb/erab381] [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: 04/05/2021] [Accepted: 08/16/2021] [Indexed: 06/13/2023]
Abstract
C4 photosynthesis is typically characterized by the spatial compartmentalization of the photosynthetic reactions into mesophyll (M) and bundle sheath (BS) cells. Initial carbon fixation within M cells gives rise to C4 acids, which are transported to the BS cells. There, C4 acids are decarboxylated so that the resulting CO2 is incorporated into the Calvin cycle. This work is focused on the study of Setaria viridis, a C4 model plant, closely related to several major feed and bioenergy grasses. First, we performed the heterologous expression and biochemical characterization of Setaria isoforms for chloroplastic NADP-malic enzyme (NADP-ME) and mitochondrial NAD-malic enzyme (NAD-ME). The kinetic parameters obtained agree with a major role for NADP-ME in the decarboxylation of the C4 acid malate in the chloroplasts of BS cells. In addition, mitochondria-located NAD-ME showed regulatory properties that could be important in the context of the operation of the C4 carbon shuttle. Secondly, we compared the proteomes of M and BS compartments and found 825 differentially accumulated proteins that could support different metabolic scenarios. Most interestingly, we found evidence of metabolic strategies to insulate the C4 core avoiding the leakage of intermediates by either up-regulation or down-regulation of chloroplastic, mitochondrial, and peroxisomal proteins. Overall, the results presented in this work provide novel data concerning the complexity of C4 metabolism, uncovering future lines of research that will undoubtedly contribute to the expansion of knowledge on this topic.
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Affiliation(s)
- Paula Calace
- Grupo de Metabolismo del Carbono y Producción Vegetal, Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Tomás Tonetti
- Instituto de Agrobiotecnología del Litoral (IAL-CONICET), Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Santa Fe, Argentina
| | - Ezequiel Margarit
- Grupo de Calidad de Frutos Cítricos, Bayas y Mejoramiento Forestal, Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Carlos M Figueroa
- Instituto de Agrobiotecnología del Litoral (IAL-CONICET), Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Santa Fe, Argentina
| | - Carlos Lobertti
- Grupo de Metabolismo del Carbono y Producción Vegetal, Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
- Laboratorio de Patogénesis Bacteriana, Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Centro Científico Tecnológico Rosario, Rosario, Argentina
| | - Carlos S Andreo
- Grupo de Metabolismo del Carbono y Producción Vegetal, Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Mariel C Gerrard Wheeler
- Grupo de Metabolismo del Carbono y Producción Vegetal, Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Mariana Saigo
- Grupo de Metabolismo del Carbono y Producción Vegetal, Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
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10
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Yang J, Bertolini E, Braud M, Preciado J, Chepote A, Jiang H, Eveland AL. The SvFUL2 transcription factor is required for inflorescence determinacy and timely flowering in Setaria viridis. PLANT PHYSIOLOGY 2021; 187:1202-1220. [PMID: 33871654 PMCID: PMC8566296 DOI: 10.1093/plphys/kiab169] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 03/22/2021] [Indexed: 05/22/2023]
Abstract
Inflorescence architecture in cereal crops directly impacts yield potential through regulation of seed number and harvesting ability. Extensive architectural diversity found in inflorescences of grass species is due to spatial and temporal activity and determinacy of meristems, which control the number and arrangement of branches and flowers, and underlie plasticity. Timing of the floral transition is also intimately associated with inflorescence development and architecture, yet little is known about the intersecting pathways and how they are rewired during development. Here, we show that a single mutation in a gene encoding an AP1/FUL-like MADS-box transcription factor significantly delays flowering time and disrupts multiple levels of meristem determinacy in panicles of the C4 model panicoid grass, Setaria viridis. Previous reports of AP1/FUL-like genes in cereals have revealed extensive functional redundancy, and in panicoid grasses, no associated inflorescence phenotypes have been described. In S. viridis, perturbation of SvFul2, both through chemical mutagenesis and gene editing, converted a normally determinate inflorescence habit to an indeterminate one, and also repressed determinacy in axillary branch and floral meristems. Our analysis of gene networks connected to disruption of SvFul2 identified regulatory hubs at the intersection of floral transition and inflorescence determinacy, providing insights into the optimization of cereal crop architecture.
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Affiliation(s)
- Jiani Yang
- Donald Danforth Plant Science Center, Saint Louis, Missouri, 63132, USA
| | - Edoardo Bertolini
- Donald Danforth Plant Science Center, Saint Louis, Missouri, 63132, USA
| | - Max Braud
- Donald Danforth Plant Science Center, Saint Louis, Missouri, 63132, USA
| | - Jesus Preciado
- National Science Foundation Research Experiences in Plant Science at the Danforth Center, Saint Louis, Missouri, 63132, USA
| | - Adriana Chepote
- Donald Danforth Plant Science Center, Saint Louis, Missouri, 63132, USA
| | - Hui Jiang
- Donald Danforth Plant Science Center, Saint Louis, Missouri, 63132, USA
| | - Andrea L Eveland
- Donald Danforth Plant Science Center, Saint Louis, Missouri, 63132, USA
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11
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Zhu C, Liu L, Crowell O, Zhao H, Brutnell TP, Jackson D, Kellogg EA. The CLV3 Homolog in Setaria viridis Selectively Controls Inflorescence Meristem Size. FRONTIERS IN PLANT SCIENCE 2021; 12:636749. [PMID: 33659018 PMCID: PMC7917188 DOI: 10.3389/fpls.2021.636749] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 01/21/2021] [Indexed: 05/17/2023]
Abstract
The CLAVATA pathway controls meristem size during inflorescence development in both eudicots and grasses, and is initiated by peptide ligands encoded by CLV3/ESR-related (CLE) genes. While CLV3 controls all shoot meristems in Arabidopsis, evidence from cereal grasses indicates that different meristem types are regulated by different CLE peptides. The rice peptide FON2 primarily controls the size of the floral meristem, whereas the orthologous peptides CLE7 and CLE14 in maize have their most dramatic effects on inflorescence and branch meristems, hinting at diversification among CLE responses in the grasses. Setaria viridis is more closely related to maize than to rice, so can be used to test whether the maize CLE network can be generalized to all members of subfamily Panicoideae. We used CRISPR-Cas9 in S. viridis to knock out the SvFON2 gene, the closest homolog to CLV3 and FON2. Svfon2 mutants developed larger inflorescence meristems, as in maize, but had normal floral meristems, unlike Osfon2, suggesting a panicoid-specific CLE network. Vegetative traits such as plant height, tiller number and leaf number were not significantly different between mutant and wild type plants, but time to heading was shorter in the mutants. In situ hybridization showed strong expression of Svfon2 in the inflorescence and branch meristems, consistent with the mutant phenotype. Using bioinformatic analysis, we predicted the co-expression network of SvFON2 and its signaling components, which included genes known to control inflorescence architecture in maize as well as genes of unknown function. The similarity between SvFON2 function in Setaria and maize suggests that its developmental specialization in inflorescence meristem control may be shared among panicoid grasses.
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Affiliation(s)
- Chuanmei Zhu
- Donald Danforth Plant Science Center, St. Louis, MO, United States
| | - Lei Liu
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States
| | - Olivia Crowell
- Donald Danforth Plant Science Center, St. Louis, MO, United States
| | - Hui Zhao
- Donald Danforth Plant Science Center, St. Louis, MO, United States
- Institute of Tropical Bioscience and Biotechnology and Hainan Key Laboratory for Biosafety Monitoring and Molecular Breeding in Off-Season Reproduction Regions, Chinese Academy of Tropical Agricultural Sciences, Haikou, China
| | - Thomas P. Brutnell
- Donald Danforth Plant Science Center, St. Louis, MO, United States
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice Development, Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, China
| | - David Jackson
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States
| | - Elizabeth A. Kellogg
- Donald Danforth Plant Science Center, St. Louis, MO, United States
- *Correspondence: Elizabeth A. Kellogg
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12
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Thielen PM, Pendleton AL, Player RA, Bowden KV, Lawton TJ, Wisecaver JH. Reference Genome for the Highly Transformable Setaria viridis ME034V. G3 (BETHESDA, MD.) 2020; 10:3467-3478. [PMID: 32694197 PMCID: PMC7534418 DOI: 10.1534/g3.120.401345] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 07/16/2020] [Indexed: 12/22/2022]
Abstract
Setaria viridis (green foxtail) is an important model system for improving cereal crops due to its diploid genome, ease of cultivation, and use of C4 photosynthesis. The S. viridis accession ME034V is exceptionally transformable, but the lack of a sequenced genome for this accession has limited its utility. We present a 397 Mb highly contiguous de novo assembly of ME034V using ultra-long nanopore sequencing technology (read N50 = 41kb). We estimate that this genome is largely complete based on our updated k-mer based genome size estimate of 401 Mb for S. viridis Genome annotation identified 37,908 protein-coding genes and >300k repetitive elements comprising 46% of the genome. We compared the ME034V assembly with two other previously sequenced Setaria genomes as well as to a diversity panel of 235 S. viridis accessions. We found the genome assemblies to be largely syntenic, but numerous unique polymorphic structural variants were discovered. Several ME034V deletions may be associated with recent retrotransposition of copia and gypsy LTR repeat families, as evidenced by their low genotype frequencies in the sampled population. Lastly, we performed a phylogenomic analysis to identify gene families that have expanded in Setaria, including those involved in specialized metabolism and plant defense response. The high continuity of the ME034V genome assembly validates the utility of ultra-long DNA sequencing to improve genetic resources for emerging model organisms. Structural variation present in Setaria illustrates the importance of obtaining the proper genome reference for genetic experiments. Thus, we anticipate that the ME034V genome will be of significant utility for the Setaria research community.
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Affiliation(s)
- Peter M Thielen
- Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland 20723
| | - Amanda L Pendleton
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907
- Purdue Center for Plant Biology, Purdue University, West Lafayette, Indiana 47907
| | - Robert A Player
- Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland 20723
| | - Kenneth V Bowden
- Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland 20723
| | - Thomas J Lawton
- Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland 20723
| | - Jennifer H Wisecaver
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907
- Purdue Center for Plant Biology, Purdue University, West Lafayette, Indiana 47907
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13
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Yang Z, Zhang H, Li X, Shen H, Gao J, Hou S, Zhang B, Mayes S, Bennett M, Ma J, Wu C, Sui Y, Han Y, Wang X. A mini foxtail millet with an Arabidopsis-like life cycle as a C 4 model system. NATURE PLANTS 2020; 6:1167-1178. [PMID: 32868891 DOI: 10.1038/s41477-020-0747-7] [Citation(s) in RCA: 85] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2019] [Accepted: 07/20/2020] [Indexed: 05/12/2023]
Abstract
Foxtail millet (Setaria italica) is an important crop species and an emerging model plant for C4 grasses. However, functional genomics research on foxtail millet is challenging because of its long generation time, relatively large stature and recalcitrance to genetic transformation. Here we report the development of xiaomi, a rapid-cycling mini foxtail millet mutant as a C4 model system. Five to six generations of xiaomi can be grown in a year in growth chambers due to its short life cycle and small plant size, similar to Arabidopsis. A point mutation in the Phytochrome C (PHYC) gene was found to be causal for these characteristics. PHYC encodes a light receptor essential for photoperiodic flowering. A reference-grade xiaomi genome comprising 429.94 Mb of sequence was assembled and a gene-expression atlas from 11 different tissues was developed. These resources, together with an established highly efficient transformation system and a multi-omics database, make xiaomi an ideal model system for functional studies of C4 plants.
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Affiliation(s)
- Zhirong Yang
- Institute of Agricultural Bioengineering, Shanxi Agricultural University, Taigu, China
- College of Arts and Sciences, Shanxi Agricultural University, Taigu, China
| | - Haoshan Zhang
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xukai Li
- Institute of Agricultural Bioengineering, Shanxi Agricultural University, Taigu, China
- College of Life Sciences, Shanxi Agricultural University, Taigu, China
| | - Huimin Shen
- College of Life Sciences, Shanxi Agricultural University, Taigu, China
| | - Jianhua Gao
- Institute of Agricultural Bioengineering, Shanxi Agricultural University, Taigu, China
- College of Life Sciences, Shanxi Agricultural University, Taigu, China
| | - Siyu Hou
- Institute of Agricultural Bioengineering, Shanxi Agricultural University, Taigu, China
- College of Agriculture, Shanxi Agricultural University, Taigu, China
| | - Bin Zhang
- Institute of Agricultural Bioengineering, Shanxi Agricultural University, Taigu, China
- College of Agriculture, Shanxi Agricultural University, Taigu, China
| | - Sean Mayes
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, UK
| | - Malcolm Bennett
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, UK
| | - Jianxin Ma
- Department of Agronomy, Purdue University, West Lafayette, IN, USA
| | - Chuanyin Wu
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yi Sui
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China.
| | - Yuanhuai Han
- Institute of Agricultural Bioengineering, Shanxi Agricultural University, Taigu, China.
- College of Agriculture, Shanxi Agricultural University, Taigu, China.
| | - Xingchun Wang
- Institute of Agricultural Bioengineering, Shanxi Agricultural University, Taigu, China.
- College of Life Sciences, Shanxi Agricultural University, Taigu, China.
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14
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Cesarino I, Dello Ioio R, Kirschner GK, Ogden MS, Picard KL, Rast-Somssich MI, Somssich M. Plant science's next top models. ANNALS OF BOTANY 2020; 126:1-23. [PMID: 32271862 PMCID: PMC7304477 DOI: 10.1093/aob/mcaa063] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 04/08/2020] [Indexed: 05/05/2023]
Abstract
BACKGROUND Model organisms are at the core of life science research. Notable examples include the mouse as a model for humans, baker's yeast for eukaryotic unicellular life and simple genetics, or the enterobacteria phage λ in virology. Plant research was an exception to this rule, with researchers relying on a variety of non-model plants until the eventual adoption of Arabidopsis thaliana as primary plant model in the 1980s. This proved to be an unprecedented success, and several secondary plant models have since been established. Currently, we are experiencing another wave of expansion in the set of plant models. SCOPE Since the 2000s, new model plants have been established to study numerous aspects of plant biology, such as the evolution of land plants, grasses, invasive and parasitic plant life, adaptation to environmental challenges, and the development of morphological diversity. Concurrent with the establishment of new plant models, the advent of the 'omics' era in biology has led to a resurgence of the more complex non-model plants. With this review, we introduce some of the new and fascinating plant models, outline why they are interesting subjects to study, the questions they will help to answer, and the molecular tools that have been established and are available to researchers. CONCLUSIONS Understanding the molecular mechanisms underlying all aspects of plant biology can only be achieved with the adoption of a comprehensive set of models, each of which allows the assessment of at least one aspect of plant life. The model plants described here represent a step forward towards our goal to explore and comprehend the diversity of plant form and function. Still, several questions remain unanswered, but the constant development of novel technologies in molecular biology and bioinformatics is already paving the way for the next generation of plant models.
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Affiliation(s)
- Igor Cesarino
- Department of Botany, Institute of Biosciences, University of São Paulo, Rua do Matão 277, Butantã, São Paulo, Brazil
| | - Raffaele Dello Ioio
- Dipartimento di Biologia e Biotecnologie, Università di Roma La Sapienza, Rome, Italy
| | - Gwendolyn K Kirschner
- University of Bonn, Institute of Crop Science and Resource Conservation (INRES), Division of Crop Functional Genomics, Bonn, Germany
| | - Michael S Ogden
- School of BioSciences, University of Melbourne, Parkville, VIC, Australia
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Kelsey L Picard
- School of Natural Sciences, University of Tasmania, Hobart, TAS, Australia
| | - Madlen I Rast-Somssich
- School of Biological Sciences, Monash University, Clayton Campus, Melbourne, VIC, Australia
| | - Marc Somssich
- School of BioSciences, University of Melbourne, Parkville, VIC, Australia
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15
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Hu H, Mauro-Herrera M, Doust AN. Domestication and Improvement in the Model C4 Grass, Setaria. FRONTIERS IN PLANT SCIENCE 2018; 9:719. [PMID: 29896214 PMCID: PMC5986938 DOI: 10.3389/fpls.2018.00719] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Accepted: 05/14/2018] [Indexed: 05/17/2023]
Abstract
Setaria viridis (green foxtail) and its domesticated relative S. italica (foxtail millet) are diploid C4 panicoid grasses that are being developed as model systems for studying grass genomics, genetics, development, and evolution. According to archeological evidence, foxtail millet was domesticated from green foxtail approximately 9,000 to 6,000 YBP in China. Under long-term human selection, domesticated foxtail millet developed many traits adapted to human cultivation and agricultural production. In comparison with its wild ancestor, foxtail millet has fewer vegetative branches, reduced grain shattering, delayed flowering time and less photoperiod sensitivity. Foxtail millet is the only present-day crop in the genus Setaria, although archeological records suggest that other species were domesticated and later abandoned in the last 10,000 years. We present an overview of domestication in foxtail millet, by reviewing recent studies on the genetic regulation of several domesticated traits in foxtail millet and discuss how the foxtail millet and green foxtail system could be further developed to both better understand its domestication history, and to provide more tools for future breeding efforts.
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Affiliation(s)
| | | | - Andrew N. Doust
- Department of Plant Biology, Ecology, and Evolution, Oklahoma State University, Stillwater, OK, United States
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16
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Kaur J, Roy Choudhury S, Vijayakumar A, Hovis L, Rhodes Z, Polzin R, Blumenthal D, Pandey S. Arabidopsis Type III Gγ Protein AGG3 Is a Positive Regulator of Yield and Stress Responses in the Model Monocot Setaria viridis. FRONTIERS IN PLANT SCIENCE 2018; 9:109. [PMID: 29479357 PMCID: PMC5811934 DOI: 10.3389/fpls.2018.00109] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 01/19/2018] [Indexed: 05/10/2023]
Abstract
Heterotrimeric G-proteins are key regulators of a multitude of growth and development pathways in eukaryotes. Along with the conserved G-protein components found in all organisms, plants have certain novel variants with unique architecture, which may be involved in the regulation of plant-specific traits. The higher plant-specific type III (or Class C) Gγ protein, which possesses a large C terminal extension, represented by AGG3 in Arabidopsis, is one such variant of canonical Gγ proteins. The type III Gγ proteins are involved in regulation of many agronomically important traits in plants, including seed yield, organ size regulation, abscisic acid (ABA)-dependent signaling and stress responses, and nitrogen use efficiency. However, the extant data, especially in the monocots, present a relatively complex and sometimes contradictory picture of the regulatory role of these proteins. It remains unclear if the positive traits observed in certain naturally occurring populations are due to the presence of specific allelic variants of the proteins or due to the altered expression of the gene itself. To address these possibilities, we have overexpressed the Arabidopsis AGG3 gene in the model monocot Setaria viridis and systematically evaluated its role in conferring agriculturally relevant phenotypes. Our data show that AtAGG3 is indeed functional in Setaria and suggest that a subset of the traits affected by the type III Gγ proteins are indeed positively correlated with the gene expression level, while others might have more complex, allele specific regulation.
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