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1.
Plant Cell Physiol ; 62(6): 959-970, 2021 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-34037236

RESUMO

Most land plants entertain a mutualistic symbiosis known as arbuscular mycorrhiza with fungi (Glomeromycota) that provide them with essential mineral nutrients, in particular phosphate (Pi), and protect them from biotic and abiotic stress. Arbuscular mycorrhizal (AM) symbiosis increases plant productivity and biodiversity and is therefore relevant for both natural plant communities and crop production. However, AM fungal populations suffer from intense farming practices in agricultural soils, in particular Pi fertilization. The dilemma between natural fertilization from AM symbiosis and chemical fertilization has raised major concern and emphasizes the need to better understand the mechanisms by which Pi suppresses AM symbiosis. Here, we test the hypothesis that Pi may interfere with AM symbiosis via the phytohormone gibberellic acid (GA) in the Solanaceous model systems Petunia hybrida and Nicotiana tabacum. Indeed, we find that GA is inhibitory to AM symbiosis and that Pi may cause GA levels to increase in mycorrhizal roots. Consistent with a role of endogenous GA as an inhibitor of AM development, GA-defective N. tabacum lines expressing a GA-metabolizing enzyme (GA methyltransferase-GAMT) are colonized more quickly by the AM fungus Rhizoglomus irregulare, and exogenous Pi is less effective in inhibiting AM colonization in these lines. Systematic gene expression analysis of GA-related genes reveals a complex picture, in which GA degradation by GA2 oxidase plays a prominent role. These findings reveal potential targets for crop breeding that could reduce Pi suppression of AM symbiosis, thereby reconciling the advantages of Pi fertilization with the diverse benefits of AM symbiosis.


Assuntos
Giberelinas/metabolismo , Micorrizas/fisiologia , Petunia/fisiologia , Fosfatos/metabolismo , Tabaco/fisiologia , Regulação da Expressão Gênica de Plantas , Reguladores de Crescimento de Plantas/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/genética , Raízes de Plantas/microbiologia , Plantas Geneticamente Modificadas , Transdução de Sinais , Simbiose
2.
Trends Plant Sci ; 26(2): 111-123, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33011084

RESUMO

Arbuscular mycorrhizal fungi (AMF) live as obligate root symbionts on almost all land plants. They have long been regarded as ancient asexuals that have propagated clonally for millions of years. However, genomic studies in Rhizophagus irregularis and other AMF revealed many features indicative of sex. Surprisingly, comparative genomics of conspecific isolates of R. irregularis revealed an unexpected interstrain diversity, suggesting that AMF carry a high number of lineage-specific (LS) genes. Intriguingly, cryptic sex and LS genomic regions have previously been reported in a number of fungal pathogens of plants and humans. Here, we discuss these genomic similarities and highlight their potential relevance for AMF adaptation to the environment and for symbiotic functioning.


Assuntos
Glomeromycota , Micorrizas , Fungos , Genoma Fúngico , Micorrizas/genética , Simbiose/genética
3.
New Phytol ; 229(6): 3481-3496, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33231304

RESUMO

The intimate association of host and fungus in arbuscular mycorrhizal (AM) symbiosis can potentially trigger induction of host defence mechanisms against the fungus, implying that successful symbiosis requires suppression of defence. We addressed this phenomenon by using AM-defective vapyrin (vpy) mutants in Petunia hybrida, including a new allele (vpy-3) with a transposon insertion close to the ATG start codon. We explore whether abortion of fungal infection in vpy mutants is associated with the induction of defence markers, such as cell wall alterations, accumulation of reactive oxygen species (ROS), defence hormones and induction of pathogenesis-related (PR) genes. We show that vpy mutants exhibit a strong resistance against intracellular colonization, which is associated with the generation of cell wall appositions (papillae) with lignin impregnation at fungal entry sites, while no accumulation of defence hormones, ROS or callose was observed. Systematic analysis of PR gene expression revealed that several PR genes are induced in mycorrhizal roots of the wild-type, and even more in vpy plants. Some PR genes are induced exclusively in vpy mutants. Our results suggest that VPY is involved in avoiding or suppressing the induction of a cellular defence syndrome that involves localized lignin deposition and PR gene induction.


Assuntos
Micorrizas , Petunia , Expressão Gênica , Regulação da Expressão Gênica de Plantas , Lignina , Micorrizas/genética , Petunia/genética , Raízes de Plantas , Simbiose
4.
Nat Nanotechnol ; 16(3): 344-353, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33318639

RESUMO

In plants, pathogen attack can induce an immune response known as systemic acquired resistance that protects against a broad spectrum of pathogens. In the search for safer agrochemicals, silica nanoparticles (SiO2 NPs; food additive E551) have recently been proposed as a new tool. However, initial results are controversial, and the molecular mechanisms of SiO2 NP-induced disease resistance are unknown. Here we show that SiO2 NPs, as well as soluble Si(OH)4, can induce systemic acquired resistance in a dose-dependent manner, which involves the defence hormone salicylic acid. Nanoparticle uptake and action occurred exclusively through the stomata (leaf pores facilitating gas exchange) and involved extracellular adsorption in the air spaces in the spongy mesophyll of the leaf. In contrast to the treatment with SiO2 NPs, the induction of systemic acquired resistance by Si(OH)4 was problematic since high Si(OH)4 concentrations caused stress. We conclude that SiO2 NPs have the potential to serve as an inexpensive, highly efficient, safe and sustainable alternative for plant disease protection.


Assuntos
Arabidopsis/efeitos dos fármacos , Resistência à Doença/genética , Nanopartículas/química , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Doenças das Plantas/genética , Doenças das Plantas/prevenção & controle , Espécies Reativas de Oxigênio/química , Ácido Salicílico/química , Dióxido de Silício/química , Dióxido de Silício/farmacologia
5.
Development ; 147(11)2020 05 29.
Artigo em Inglês | MEDLINE | ID: mdl-32376679

RESUMO

The VAPYRIN (VPY) gene in Medicago truncatula and Petunia hybrida is required for arbuscular mycorrhizal (AM) symbiosis. The moss Physcomitrella patens has a close homolog (VPY-like, VPYL), although it does not form AM. Here, we explore the phylogeny of VPY and VPYL in land plants, and study the expression and developmental function of VPYL in P patens We show that VPYL is expressed primarily in the protonema, the early filamentous stage of moss development, and later in rhizoids arising from the leafy gametophores and in adult phyllids. Knockout mutants have specific phenotypes in branching of the protonema and in cell division of the leaves (phyllids) in gametophores. The mutants are responsive to auxin and strigolactone, which are involved in regulation of protonemal branching, indicating that hormonal signaling in the mutants is not affected in hormonal signaling. Taken together, these results suggest that VPYL exerts negative regulation of protonemal branching and cell division in phyllids. We discuss VPY and VPYL phylogeny and function in land plants in the context of AM symbiosis in angiosperms and development in the moss.


Assuntos
Bryopsida/crescimento & desenvolvimento , Proteínas de Plantas/metabolismo , Bryopsida/metabolismo , Evolução Molecular , Regulação da Expressão Gênica de Plantas , Compostos Heterocíclicos com 3 Anéis/metabolismo , Ácidos Indolacéticos/metabolismo , Lactonas/metabolismo , Mutagênese , Fenótipo , Filogenia , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Proteínas de Plantas/classificação , Proteínas de Plantas/genética , Caules de Planta/crescimento & desenvolvimento , Caules de Planta/metabolismo , Plantas Geneticamente Modificadas/metabolismo , Regiões Promotoras Genéticas , Transdução de Sinais
6.
Curr Biol ; 29(24): 4249-4259.e5, 2019 12 16.
Artigo em Inglês | MEDLINE | ID: mdl-31813608

RESUMO

Bacterial lipo-chitooligosaccharides (LCOs) are key mediators of the nitrogen-fixing root nodule symbiosis (RNS) in legumes. The isolation of LCOs from arbuscular mycorrhizal fungi suggested that LCOs are also signaling molecules in arbuscular mycorrhiza (AM). However, the corresponding plant receptors have remained uncharacterized. Here we show that petunia and tomato mutants in the LysM receptor-like kinases LYK10 are impaired in AM formation. Petunia and tomato LYK10 proteins have a high affinity for LCOs (Kd in the nM range) comparable to that previously reported for a legume LCO receptor essential for the RNS. Interestingly, the tomato and petunia LYK10 promoters, when introduced into a legume, were active in nodules similarly to the promoter of the legume orthologous gene. Moreover, tomato and petunia LYK10 coding sequences restored nodulation in legumes mutated in their orthologs. This combination of genetic and biochemical data clearly pinpoints Solanaceous LYK10 as part of an ancestral LCO perception system involved in AM establishment, which has been directly recruited during evolution of the RNS in legumes.


Assuntos
Lipopolissacarídeos/metabolismo , Micorrizas/fisiologia , Rhizobium/metabolismo , Quitina/análogos & derivados , Quitina/metabolismo , Fabaceae/metabolismo , Fabaceae/microbiologia , Regulação da Expressão Gênica de Plantas/genética , Lycopersicon esculentum/metabolismo , Micorrizas/metabolismo , Petunia/metabolismo , Proteínas de Plantas/metabolismo , Proteínas Quinases/metabolismo , Transdução de Sinais/genética , Simbiose/genética
7.
iScience ; 17: 144-154, 2019 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-31276958

RESUMO

The majority of land plants have two suberized root barriers: the endodermis and the hypodermis (exodermis). Both barriers bear non-suberized passage cells that are thought to regulate water and nutrient exchange between the root and the soil. We learned a lot about endodermal passage cells, whereas our knowledge on hypodermal passage cells (HPCs) is still very scarce. Here we report on factors regulating the HPC number in Petunia roots. Strigolactones exhibit a positive effect, whereas supply of abscisic acid (ABA), ethylene, and auxin result in a strong reduction of the HPC number. Unexpectedly the strigolactone signaling mutant d14/dad2 showed significantly higher HPC numbers than the wild-type. In contrast, its mutant counterpart max2 of the heterodimeric receptor DAD2/MAX2 displayed a significant decrease in HPC number. A mutation in the Petunia karrikin sensor KAI2 exhibits drastically decreased HPC amounts, supporting the hypothesis that the dimeric KAI2/MAX2 receptor is central in determining the HPC number.

8.
Front Plant Sci ; 10: 666, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31231402

RESUMO

Arbuscular mycorrhiza (AM) is a symbiosis between plants and AM fungi that requires the intracellular accommodation of the fungal partner in the host. For reciprocal nutrient exchange, AM fungi form intracellular arbuscules that are surrounded by the peri-arbuscular membrane. This membrane, together with the fungal plasma membrane, and the space in between, constitute the symbiotic interface, over which nutrients are exchanged. Intracellular establishment of AM fungi requires the VAPYRIN protein which is induced in colonized cells, and which localizes to numerous small mobile structures of unknown identity (Vapyrin-bodies). In order to characterize the identity and function of the Vapyrin-bodies we pursued a dual strategy. First, we co-expressed fluorescently tagged VAPYRIN with a range of subcellular marker proteins, and secondly, we employed biochemical tools to identify interacting partner proteins of VAPYRIN. As an important tool for the quantitative analysis of confocal microscopic data sets from co-expression of fluorescent proteins, we developed a semi-automated image analysis pipeline that allows for precise spatio-temporal quantification of protein co-localization and of the dynamics of organelle association from movies. Taken together, these experiments revealed that Vapyrin-bodies have an endosomal identity with trans-Golgi features, and that VAPYRIN interacts with a symbiotic R-SNARE of the VAMP721 family, that localizes to the same compartment.

9.
Front Plant Sci ; 9: 1270, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30233616

RESUMO

Arbuscular mycorrhiza (AM) is the most common symbiotic association of plants with microbes. AM fungi occur in the majority of natural habitats and they provide a range of important ecological services, in particular by improving plant nutrition, stress resistance and tolerance, soil structure and fertility. AM fungi also interact with most crop plants including cereals, vegetables, and fruit trees, therefore, they receive increasing attention for their potential use in sustainable agriculture. Basic research of the past decade has revealed the existence of a dedicated recognition and signaling pathway that is required for AM. Furthermore, recent evidence provided new insight into the exchange of nutritional benefits between the symbiotic partners. The great potential for application of AM has given rise to a thriving industry for AM-related products for agriculture, horticulture, and landscaping. Here, we discuss new developments in these fields, and we highlight future potential and limits toward the use of AM fungi for plant production.

10.
Plant Signal Behav ; 13(6): e1471299, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29995575

RESUMO

Angiosperm inflorescences develop in two fundamentally different ways. In monopodial plants, for example in Arabidopsis thaliana, the flowers are initiated as lateral appendages of a central indeterminate inflorescence meristem. In sympodial plants, flowers arise by terminal differentiation of the inflorescence meristem, while further inflorescence development proceeds from new sympodial meristems that are generated at the flank of the terminal flower. We have used the sympodial model species Petunia hybrida to investigate inflorescence development. Here, we describe a mutant, bonsai (bns), which is defective in flower formation, inflorescence branching, and control of meristem size. Detailed microscopic analysis revealed that bns meristems retain vegetative charateristics including spiral phyllotaxis. Consistent with a block in flower formation, bns mutants exhibit a deregulated expression of various MADS-box genes. Molecular analysis revealed that the bns mutant carries a transposon insertion in the previously described EVERGREEN (EVG) gene, which belongs to the WUSCHEL-LIKE HOMEOBOX (WOX) transcription factor gene family. EVG falls in the WOX9 subfamily, which has diverse developmental functions in angiosperms. The comparison of WOX9 orthologues in five model species for flowering shows that these genes play functionally divergent roles in monopodial and sympodial plants, indicating that the WOX9 regulatory node may have played an important role in the evolution of shoot architecture.


Assuntos
Proteínas de Domínio MADS/metabolismo , Petunia/metabolismo , Proteínas de Plantas/metabolismo , Flores/genética , Flores/metabolismo , Regulação da Expressão Gênica de Plantas , Proteínas de Domínio MADS/genética , Meristema/genética , Meristema/metabolismo , Petunia/genética , Proteínas de Plantas/genética
11.
Plant Cell ; 29(12): 2959-2973, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-29167321

RESUMO

How complex developmental-genetic networks are translated into organs with specific 3D shapes remains an open question. This question is particularly challenging because the elaboration of specific shapes is in essence a question of mechanics. In plants, this means how the genetic circuitry affects the cell wall. The mechanical properties of the wall and their spatial variation are the key factors controlling morphogenesis in plants. However, these properties are difficult to measure and investigating their relation to genetic regulation is particularly challenging. To measure spatial variation of mechanical properties, one must determine the deformation of a tissue in response to a known force with cellular resolution. Here, we present an automated confocal micro-extensometer (ACME), which greatly expands the scope of existing methods for measuring mechanical properties. Unlike classical extensometers, ACME is mounted on a confocal microscope and uses confocal images to compute the deformation of the tissue directly from biological markers, thus providing 3D cellular scale information and improved accuracy. Additionally, ACME is suitable for measuring the mechanical responses in live tissue. As a proof of concept, we demonstrate that the plant hormone gibberellic acid induces a spatial gradient in mechanical properties along the length of the Arabidopsis thaliana hypocotyl.


Assuntos
Arabidopsis/citologia , Microscopia Confocal/instrumentação , Células Vegetais/química , Automação , Fenômenos Biomecânicos , Parede Celular/efeitos dos fármacos , Parede Celular/fisiologia , Elasticidade , Giberelinas/farmacologia , Hipocótilo/citologia , Hipocótilo/efeitos dos fármacos , Hipocótilo/crescimento & desenvolvimento , Hipocótilo/efeitos da radiação , Luz , Modelos Biológicos , Células Vegetais/efeitos dos fármacos , Estresse Fisiológico/efeitos dos fármacos
12.
BMC Genomics ; 18(1): 589, 2017 08 08.
Artigo em Inglês | MEDLINE | ID: mdl-28789611

RESUMO

BACKGROUND: Development of arbuscular mycorrhiza (AM) requires a fundamental reprogramming of root cells for symbiosis. This involves the induction of hundreds of genes in the host. A recently identified GRAS-type transcription factor in Petunia hybrida, ATA/RAM1, is required for the induction of host genes during AM, and for morphogenesis of the fungal endosymbiont. To better understand the role of RAM1 in symbiosis, we set out to identify all genes that depend on activation by RAM1 in mycorrhizal roots. RESULTS: We have carried out a transcript profiling experiment by RNAseq of mycorrhizal plants vs. non-mycorrhizal controls in wild type and ram1 mutants. The results show that the expression of early genes required for AM, such as the strigolactone biosynthetic genes and the common symbiosis signalling genes, is independent of RAM1. In contrast, genes that are involved at later stages of symbiosis, for example for nutrient exchange in cortex cells, require RAM1 for induction. RAM1 itself is highly induced in mycorrhizal roots together with many other transcription factors, in particular GRAS proteins. CONCLUSION: Since RAM1 has previously been shown to be directly activated by the common symbiosis signalling pathway through CYCLOPS, we conclude that it acts as an early transcriptional switch that induces many AM-related genes, among them genes that are essential for the development of arbuscules, such as STR, STR2, RAM2, and PT4, besides hundreds of additional RAM1-dependent genes the role of which in symbiosis remains to be explored. Taken together, these results indicate that the defect in the morphogenesis of the fungal arbuscules in ram1 mutants may be an indirect consequence of functional defects in the host, which interfere with nutrient exchange and possibly other functions on which the fungus depends.


Assuntos
Micorrizas/genética , Micorrizas/metabolismo , Petunia/genética , Petunia/metabolismo , Proteínas de Plantas/metabolismo , Fatores de Transcrição/metabolismo , Transcrição Genética , Ontologia Genética , Mutação , RNA Mensageiro/genética
13.
Trends Plant Sci ; 22(8): 652-660, 2017 08.
Artigo em Inglês | MEDLINE | ID: mdl-28622919

RESUMO

Most plants entertain mutualistic interactions known as arbuscular mycorrhiza (AM) with soil fungi (Glomeromycota) which provide them with mineral nutrients in exchange for reduced carbon from the plant. Mycorrhizal roots represent strong carbon sinks in which hexoses are transferred from the plant host to the fungus. However, most of the carbon in AM fungi is stored in the form of lipids. The absence of the type I fatty acid synthase (FAS-I) complex from the AM fungal model species Rhizophagus irregularis suggests that lipids may also have a role in nutrition of the fungal partner. This hypothesis is supported by the concerted induction of host genes involved in lipid metabolism. We explore the possible roles of lipids in the light of recent literature on AM symbiosis.


Assuntos
Metabolismo dos Carboidratos , Glomeromycota/fisiologia , Metabolismo dos Lipídeos , Micorrizas/fisiologia , Plantas/microbiologia , Carbono/metabolismo , Raízes de Plantas/microbiologia , Plantas/metabolismo , Simbiose
14.
Nat Plants ; 2(6): 16074, 2016 05 27.
Artigo em Inglês | MEDLINE | ID: mdl-27255838

RESUMO

Petunia hybrida is a popular bedding plant that has a long history as a genetic model system. We report the whole-genome sequencing and assembly of inbred derivatives of its two wild parents, P. axillaris N and P. inflata S6. The assemblies include 91.3% and 90.2% coverage of their diploid genomes (1.4 Gb; 2n = 14) containing 32,928 and 36,697 protein-coding genes, respectively. The genomes reveal that the Petunia lineage has experienced at least two rounds of hexaploidization: the older gamma event, which is shared with most Eudicots, and a more recent Solanaceae event that is shared with tomato and other solanaceous species. Transcription factors involved in the shift from bee to moth pollination reside in particularly dynamic regions of the genome, which may have been key to the remarkable diversity of floral colour patterns and pollination systems. The high-quality genome sequences will enhance the value of Petunia as a model system for research on unique biological phenomena such as small RNAs, symbiosis, self-incompatibility and circadian rhythms.


Assuntos
Evolução Molecular , Genoma de Planta , Hibridização Genética , Petunia/genética , Poliploidia
15.
PLoS One ; 10(7): e0127905, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26154262

RESUMO

Plants are highly plastic in their potential to adapt to changing environmental conditions. For example, they can selectively promote the relative growth of the root and the shoot in response to limiting supply of mineral nutrients and light, respectively, a phenomenon that is referred to as balanced growth or functional equilibrium. To gain insight into the regulatory network that controls this phenomenon, we took a systems biology approach that combines experimental work with mathematical modeling. We developed a mathematical model representing the activities of the root (nutrient and water uptake) and the shoot (photosynthesis), and their interactions through the exchange of the substrates sugar and phosphate (Pi). The model has been calibrated and validated with two independent experimental data sets obtained with Petunia hybrida. It involves a realistic environment with a day-and-night cycle, which necessitated the introduction of a transitory carbohydrate storage pool and an endogenous clock for coordination of metabolism with the environment. Our main goal was to grasp the dynamic adaptation of shoot:root ratio as a result of changes in light and Pi supply. The results of our study are in agreement with balanced growth hypothesis, suggesting that plants maintain a functional equilibrium between shoot and root activity based on differential growth of these two compartments. Furthermore, our results indicate that resource partitioning can be understood as the emergent property of many local physiological processes in the shoot and the root without explicit partitioning functions. Based on its encouraging predictive power, the model will be further developed as a tool to analyze resource partitioning in shoot and root crops.


Assuntos
Modelos Biológicos , Petunia/fisiologia , Desenvolvimento Vegetal , Raízes de Plantas/fisiologia , Brotos de Planta/fisiologia , Adaptação Fisiológica/efeitos dos fármacos , Adaptação Fisiológica/efeitos da radiação , Simulação por Computador , Luz , Petunia/anatomia & histologia , Petunia/efeitos dos fármacos , Petunia/efeitos da radiação , Floema/efeitos dos fármacos , Floema/fisiologia , Floema/efeitos da radiação , Fosfatos/metabolismo , Fosfatos/farmacologia , Desenvolvimento Vegetal/efeitos dos fármacos , Desenvolvimento Vegetal/efeitos da radiação , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/efeitos da radiação , Brotos de Planta/efeitos dos fármacos , Brotos de Planta/efeitos da radiação , Reprodutibilidade dos Testes
16.
Development ; 142(11): 1992-2001, 2015 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-25953346

RESUMO

The spatial arrangement of leaves and flowers around the stem, known as phyllotaxis, is controlled by an auxin-dependent reiterative mechanism that leads to regular spacing of the organs and thereby to remarkably precise phyllotactic patterns. The mechanism is based on the active cellular transport of the phytohormone auxin by cellular influx and efflux carriers, such as AUX1 and PIN1. Their important role in phyllotaxis is evident from mutant phenotypes, but their exact roles in space and time are difficult to address due to the strong pleiotropic phenotypes of most mutants in phyllotaxis. Models of phyllotaxis invoke the accumulation of auxin at leaf initials and removal of auxin through their developing vascular strand, the midvein. We have developed a precise microsurgical tool to ablate the midvein at high spatial and temporal resolution in order to test its function in leaf formation and phyllotaxis. Using amplified femtosecond laser pulses, we ablated the internal tissues in young leaf primordia of tomato (Solanum lycopersicum) without damaging the overlying L1 and L2 layers. Our results show that ablation of the future midvein leads to a transient accumulation of auxin in the primordia and to an increase in their width. Phyllotaxis was transiently affected after midvein ablations, but readjusted after two plastochrons. These results indicate that the developing midvein is involved in the basipetal transport of auxin through young primordia, which contributes to phyllotactic spacing and stability.


Assuntos
Ácidos Indolacéticos/metabolismo , Lycopersicon esculentum/anatomia & histologia , Lycopersicon esculentum/embriologia , Folhas de Planta/anatomia & histologia , Folhas de Planta/embriologia , Proteínas de Fluorescência Verde/metabolismo , Lycopersicon esculentum/genética , Tamanho do Órgão , Plantas Geneticamente Modificadas , Proteínas Recombinantes de Fusão/metabolismo
17.
Plant Physiol ; 168(3): 788-97, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25971550

RESUMO

Arbuscular mycorrhiza (AM) is a mutual symbiosis that involves a complex symbiotic interface over which nutrients are exchanged between the plant host and the AM fungus. Dozens of genes in the host are required for the establishment and functioning of the interaction, among them nutrient transporters that mediate the uptake of mineral nutrients delivered by the fungal arbuscules. We have isolated in a genetic mutant screen a petunia (Petunia hybrida) Gibberellic Acid Insensitive, Repressor of Gibberellic Acid Insensitive, and Scarecrow (GRAS)-type transcription factor, Atypical Arbuscule (ATA), that acts as the central regulator of AM-related genes and is required for the morphogenesis of arbuscules. Forced mycorrhizal inoculations from neighboring wild-type plants revealed an additional role of ATA in restricting mycorrhizal colonization of the root meristem. The lack of ATA, which represents the ortholog of Required For Arbuscular Mycorrhiza1 in Medicago truncatula, renders the interaction completely ineffective, hence demonstrating the central role of AM-related genes for arbuscule development and function.


Assuntos
Regulação da Expressão Gênica de Plantas , Micorrizas/crescimento & desenvolvimento , Petunia/genética , Petunia/microbiologia , Proteínas de Plantas/metabolismo , Simbiose/genética , Fatores de Transcrição/metabolismo , Contagem de Colônia Microbiana , Genes de Plantas , Loci Gênicos , Medicago truncatula/genética , Medicago truncatula/microbiologia , Meristema/genética , Meristema/microbiologia , Dados de Sequência Molecular , Morfogênese , Mutação/genética , Fenótipo , Proteínas de Plantas/genética , Fatores de Transcrição/genética
19.
Trends Plant Sci ; 20(6): 344-50, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25868653

RESUMO

Roots and flowers are formed at the extreme ends of plants and they differ in almost every aspect of their development and function; even so, they exhibit surprising molecular commonalities. For example, the calcium and calmodulin-dependent protein kinase (CCaMK) plays a central role in root symbioses with fungi and bacteria, but is also highly expressed in developing anthers. Moreover, independent evidence from transcriptomics, phylogenomics, and genetics reveals common developmental elements in root symbioses and reproductive development. We discuss the significance of these overlaps, and we argue that an integrated comparative view of the two phenomena will stimulate research and provide new insight, not only into shared components, but also into the specific aspects of anther development and root symbioses.


Assuntos
Flores/fisiologia , Micorrizas/fisiologia , Proteínas Quinases Dependentes de Cálcio-Calmodulina/metabolismo , Flores/crescimento & desenvolvimento , Metabolismo dos Lipídeos , Polinização , Simbiose
20.
BMC Plant Biol ; 14: 333, 2014 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-25465219

RESUMO

BACKGROUND: Genes involved in arbuscular mycorrhizal (AM) symbiosis have been identified primarily by mutant screens, followed by identification of the mutated genes (forward genetics). In addition, a number of AM-related genes has been identified by their AM-related expression patterns, and their function has subsequently been elucidated by knock-down or knock-out approaches (reverse genetics). However, genes that are members of functionally redundant gene families, or genes that have a vital function and therefore result in lethal mutant phenotypes, are difficult to identify. If such genes are constitutively expressed and therefore escape differential expression analyses, they remain elusive. The goal of this study was to systematically search for AM-related genes with a bioinformatics strategy that is insensitive to these problems. The central element of our approach is based on the fact that many AM-related genes are conserved only among AM-competent species. RESULTS: Our approach involves genome-wide comparisons at the proteome level of AM-competent host species with non-mycorrhizal species. Using a clustering method we first established orthologous/paralogous relationships and subsequently identified protein clusters that contain members only of the AM-competent species. Proteins of these clusters were then analyzed in an extended set of 16 plant species and ranked based on their relatedness among AM-competent monocot and dicot species, relative to non-mycorrhizal species. In addition, we combined the information on the protein-coding sequence with gene expression data and with promoter analysis. As a result we present a list of yet uncharacterized proteins that show a strongly AM-related pattern of sequence conservation, indicating that the respective genes may have been under selection for a function in AM. Among the top candidates are three genes that encode a small family of similar receptor-like kinases that are related to the S-locus receptor kinases involved in sporophytic self-incompatibility. CONCLUSIONS: We present a new systematic strategy of gene discovery based on conservation of the protein-coding sequence that complements classical forward and reverse genetics. This strategy can be applied to diverse other biological phenomena if species with established genome sequences fall into distinguished groups that differ in a defined functional trait of interest.


Assuntos
Biologia Computacional , Evolução Molecular , Regulação da Expressão Gênica de Plantas , Magnoliopsida/genética , Magnoliopsida/microbiologia , Micorrizas/fisiologia , Proteínas de Plantas/genética , Perfilação da Expressão Gênica , Magnoliopsida/metabolismo , Filogenia , Proteínas de Plantas/metabolismo , Regiões Promotoras Genéticas/genética , Simbiose
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