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1.
Int J Mol Sci ; 25(9)2024 Apr 23.
Artículo en Inglés | MEDLINE | ID: mdl-38731801

RESUMEN

Leaf movement is a manifestation of plant response to the changing internal and external environment, aiming to optimize plant growth and development. Leaf movement is usually driven by a specialized motor organ, the pulvinus, and this movement is associated with different changes in volume and expansion on the two sides of the pulvinus. Blue light, auxin, GA, H+-ATPase, K+, Cl-, Ca2+, actin, and aquaporin collectively influence the changes in water flux in the tissue of the extensor and flexor of the pulvinus to establish a turgor pressure difference, thereby controlling leaf movement. However, how these factors regulate the multicellular motility of the pulvinus tissues in a species remains obscure. In addition, model plants such as Medicago truncatula, Mimosa pudica, and Samanea saman have been used to study pulvinus-driven leaf movement, showing a similarity in their pulvinus movement mechanisms. In this review, we summarize past research findings from the three model plants, and using Medicago truncatula as an example, suggest that genes regulating pulvinus movement are also involved in regulating plant growth and development. We also propose a model in which the variation of ion flux and water flux are critical steps to pulvinus movement and highlight questions for future research.


Asunto(s)
Medicago truncatula , Hojas de la Planta , Pulvino , Hojas de la Planta/metabolismo , Hojas de la Planta/fisiología , Hojas de la Planta/crecimiento & desarrollo , Medicago truncatula/fisiología , Medicago truncatula/metabolismo , Medicago truncatula/genética , Medicago truncatula/crecimiento & desarrollo , Pulvino/metabolismo , Movimiento , Agua/metabolismo , Regulación de la Expresión Génica de las Plantas , Mimosa/fisiología , Mimosa/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética
2.
Curr Biol ; 34(10): R507-R509, 2024 05 20.
Artículo en Inglés | MEDLINE | ID: mdl-38772340

RESUMEN

Arbuscular mycorrhiza, an ancient symbiosis with soil fungi, support mineral nutrition in most plants. How roots recognize such symbiotic fungi has long been debated. Recent research identifies a Medicago truncatula receptor as a key player in triggering symbiont accommodation responses.


Asunto(s)
Medicago truncatula , Micorrizas , Simbiosis , Simbiosis/fisiología , Medicago truncatula/microbiología , Medicago truncatula/metabolismo , Medicago truncatula/fisiología , Micorrizas/fisiología , Raíces de Plantas/microbiología , Raíces de Plantas/metabolismo , Luz , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Luz Verde
3.
Plant Cell Environ ; 47(8): 3076-3089, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38679945

RESUMEN

Flavonoids are usually present in forms of glucosides in plants, which could be catabolized by ß-glucosidase (BGLU) to form their corresponding flavonoid aglycones. In this study, we isolated three abiotic-responsive BGLU genes (MtBGLU17, MtBGLU21 and MtBGLU22) from Medicago truncatula, and found only the recombinant MtBGLU17 protein could catalyse the hydrolysis of flavonoid glycosides. The recombinant MtBGLU17 protein is active towards a variety of flavonoid glucosides, including glucosides of flavones (apigenin and luteolin), flavonols (kaempferol and quercetin), isoflavones (genistein and daidzein) and flavanone (naringenin). In particular, the recombinant MtBGLU17 protein preferentially hydrolyses flavonoid-7-O-glucosides over their corresponding 3-O-glucosides. The content of luteoin-7-O-glucoside was reduced in the MtBGLU17 overexpression plants but increased in the Tnt-1 insertional mutant lines, whereas luteoin content was increased in the MtBGLU17 overexpression plants but reduced in the Tnt-1 insertional mutant lines. Under drought and salt (NaCl) treatment, the MtBGLU17 overexpression lines showed relatively higher DPPH content, and higher CAT and SOD activity than the wild type control. These results indicated that overexpression lines of MtBGLU17 possess higher antioxidant activity and thus confer drought and salt tolerance, implying MtBGLU17 could be potentially used as a candidate gene to improve plant abiotic stress tolerance.


Asunto(s)
Antioxidantes , Sequías , Flavonoides , Medicago truncatula , Proteínas de Plantas , Tolerancia a la Sal , beta-Glucosidasa , Medicago truncatula/genética , Medicago truncatula/enzimología , Medicago truncatula/metabolismo , Medicago truncatula/fisiología , Flavonoides/metabolismo , Antioxidantes/metabolismo , beta-Glucosidasa/metabolismo , beta-Glucosidasa/genética , Tolerancia a la Sal/genética , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Regulación de la Expresión Génica de las Plantas
4.
Plant J ; 118(3): 607-625, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38361340

RESUMEN

The conservation of GOLVEN (GLV)/ROOT MERISTEM GROWTH FACTOR (RGF) peptide encoding genes across plant genomes capable of forming roots or root-like structures underscores their potential significance in the terrestrial adaptation of plants. This study investigates the function and role of GOLVEN peptide-coding genes in Medicago truncatula. Five out of fifteen GLV/RGF genes were notably upregulated during nodule organogenesis and were differentially responsive to nitrogen deficiency and auxin treatment. Specifically, the expression of MtGLV9 and MtGLV10 at nodule initiation sites was contingent upon the NODULE INCEPTION transcription factor. Overexpression of these five nodule-induced GLV genes in hairy roots of M. truncatula and application of their synthetic peptide analogues led to a decrease in nodule count by 25-50%. Uniquely, the GOLVEN10 peptide altered the positioning of the first formed lateral root and nodule on the primary root axis, an observation we term 'noduletaxis'; this decreased the length of the lateral organ formation zone on roots. Histological section of roots treated with synthetic GOLVEN10 peptide revealed an increased cell number within the root cortical cell layers without a corresponding increase in cell length, leading to an elongation of the root likely introducing a spatiotemporal delay in organ formation. At the transcription level, the GOLVEN10 peptide suppressed expression of microtubule-related genes and exerted its effects by changing expression of a large subset of Auxin responsive genes. These findings advance our understanding of the molecular mechanisms by which GOLVEN peptides modulate root morphology, nodule ontogeny, and interactions with key transcriptional pathways.


Asunto(s)
Regulación de la Expresión Génica de las Plantas , Medicago truncatula , Proteínas de Plantas , Raíces de Plantas , Nódulos de las Raíces de las Plantas , Medicago truncatula/genética , Medicago truncatula/crecimiento & desarrollo , Medicago truncatula/metabolismo , Medicago truncatula/efectos de los fármacos , Medicago truncatula/fisiología , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/genética , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/metabolismo , Nódulos de las Raíces de las Plantas/genética , Nódulos de las Raíces de las Plantas/crecimiento & desarrollo , Nódulos de las Raíces de las Plantas/metabolismo , Nódulos de las Raíces de las Plantas/efectos de los fármacos , Ácidos Indolacéticos/metabolismo , Ácidos Indolacéticos/farmacología , Nodulación de la Raíz de la Planta/genética , Meristema/genética , Meristema/crecimiento & desarrollo , Meristema/efectos de los fármacos , Péptidos/metabolismo , Péptidos/genética
5.
Plant Cell Environ ; 46(3): 1004-1017, 2023 03.
Artículo en Inglés | MEDLINE | ID: mdl-36515398

RESUMEN

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine involved in immune response in animals. However, the role of MIFs in plants such as Medicago truncatula, particularly in symbiotic nitrogen fixation, remains unclear. An investigation of M. truncatula-Sinorhizobium meliloti symbiosis revealed that MtMIF3 was mainly expressed in the nitrogen-fixing zone of the nodules. Silencing MtMIF3 using RNA interference (Ri) technology resulted in increased nodule numbers but higher levels of bacteroid degradation in the infected cells of the nitrogen-fixing zone, suggesting that premature aging was induced in MtMIF3-Ri nodules. In agreement with this conclusion, the activities of nitrogenase, superoxide dismutase and catalase were lower than those in controls, but cysteine proteinase activity was increased in nodulated roots at 28 days postinoculation. In contrast, the overexpression of MtMIF3 inhibited nodule senescence. MtMIF3 is localized in the plasma membrane, nucleus, and cytoplasm, where it interacts with methionine sulfoxide reductase B (MsrB), which is also localized in the chloroplasts of tobacco leaf cells. Taken together, these results suggest that MtMIF3 prevents premature nodule aging and protects against oxidation by interacting with MtMsrB.


Asunto(s)
Envejecimiento Prematuro , Factores Inhibidores de la Migración de Macrófagos , Medicago truncatula , Nódulos de las Raíces de las Plantas/metabolismo , Medicago truncatula/fisiología , Factores Inhibidores de la Migración de Macrófagos/genética , Factores Inhibidores de la Migración de Macrófagos/metabolismo , Envejecimiento Prematuro/metabolismo , Fijación del Nitrógeno/fisiología , Nitrógeno/metabolismo , Simbiosis/fisiología
6.
Plant Cell Environ ; 46(2): 607-620, 2023 02.
Artículo en Inglés | MEDLINE | ID: mdl-36479691

RESUMEN

Group VII ethylene response factors (ERF-VII) are plant-specific transcription factors (TFs) known for their role in the activation of hypoxia-responsive genes under low oxygen stress but also in plant endogenous hypoxic niches. However, their function in the microaerophilic nitrogen-fixing nodules of legumes has not yet been investigated. We investigated regulation and the function of the two Medicago truncatula ERF-VII TFs (MtERF74 and MtERF75) in roots and nodules, MtERF74 and MtERF75 in response to hypoxia stress and during the nodulation process using an RNA interference strategy and targeted proteolysis of MtERF75. Knockdown of MtERF74 and MtERF75 partially blocked the induction of hypoxia-responsive genes in roots exposed to hypoxia stress. In addition, a significant reduction in nodulation capacity and nitrogen fixation activity was observed in mature nodules of double knockdown transgenic roots. Overall, the results indicate that MtERF74 and MtERF75 are involved in the induction of MtNR1 and Pgb1.1 expression for efficient Phytogb-nitric oxide respiration in the nodule.


Asunto(s)
Medicago truncatula , Fijación del Nitrógeno , Fijación del Nitrógeno/genética , Nódulos de las Raíces de las Plantas/metabolismo , Medicago truncatula/fisiología , Etilenos/metabolismo , Hipoxia/metabolismo , Simbiosis/genética , Regulación de la Expresión Génica de las Plantas , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo
7.
Plant J ; 113(5): 934-953, 2023 03.
Artículo en Inglés | MEDLINE | ID: mdl-36582182

RESUMEN

Seed longevity, the capacity to remain alive during dry storage, is pivotal to germination performance and is essential for preserving genetic diversity. It is acquired during late maturation concomitantly with seed degreening and the de-differentiation of chloroplasts into colorless, non-photosynthetic plastids, called eoplasts. As chlorophyll retention leads to poor seed performance upon sowing, these processes are important for seed vigor. However, how these processes are regulated and connected to the acquisition of seed longevity remains poorly understood. Here, we show that such a role is at least provided by ABSCISIC ACID INSENSITIVE 4 (ABI4) in the legume Medicago truncatula. Mature seeds of Mtabi4 mutants contained more chlorophyll than wild-type seeds and exhibited a 75% reduction in longevity and reduced dormancy. MtABI4 was necessary to stimulate eoplast formation, as evidenced by the significant delay in the dismantlement of photosystem II during the maturation of mutant seeds. Mtabi4 seeds also exhibited transcriptional deregulation of genes associated with retrograde signaling and transcriptional control of plastid-encoded genes. Longevity was restored when Mtabi4 seeds developed in darkness, suggesting that the shutdown of photosynthesis during maturation, rather than chlorophyll degradation per se, is a requisite for the acquisition of longevity. Indeed, the shelf life of stay green mutant seeds that retained chlorophyll was not affected. Thus, ABI4 plays a role in coordinating the dismantlement of chloroplasts during seed development to avoid damage that compromises the acquisition of seed longevity. Analysis of Mtabi4 Mtabi5 double mutants showed synergistic effects on chlorophyll retention and longevity, suggesting that they act via parallel pathways.


Asunto(s)
Ácido Abscísico , Medicago truncatula , Ácido Abscísico/metabolismo , Medicago truncatula/fisiología , Factores de Transcripción/metabolismo , Semillas/metabolismo , Germinación/genética , Regulación de la Expresión Génica de las Plantas
8.
Proc Natl Acad Sci U S A ; 119(34): e2205920119, 2022 08 23.
Artículo en Inglés | MEDLINE | ID: mdl-35972963

RESUMEN

Nuclear Ca2+ oscillations allow symbiosis signaling, facilitating plant recognition of beneficial microsymbionts, nitrogen-fixing rhizobia, and nutrient-capturing arbuscular mycorrhizal fungi. Two classes of channels, DMI1 and CNGC15, in a complex on the nuclear membrane, coordinate symbiotic Ca2+ oscillations. However, the mechanism of Ca2+ signature generation is unknown. Here, we demonstrate spontaneous activation of this channel complex, through gain-of-function mutations in DMI1, leading to spontaneous nuclear Ca2+ oscillations and spontaneous nodulation, in a CNGC15-dependent manner. The mutations destabilize a hydrogen-bond or salt-bridge network between two RCK domains, with the resultant structural changes, alongside DMI1 cation permeability, activating the channel complex. This channel complex was reconstituted in human HEK293T cell lines, with the resultant calcium influx enhanced by autoactivated DMI1 and CNGC15s. Our results demonstrate the mode of activation of this nuclear channel complex, show that DMI1 and CNGC15 are sufficient to create oscillatory Ca2+ signals, and provide insights into its native mode of induction.


Asunto(s)
Canales de Calcio , Señalización del Calcio , Medicago truncatula , Proteínas de Plantas , Nodulación de la Raíz de la Planta , Raíces de Plantas , Calcio/metabolismo , Canales de Calcio/genética , Canales de Calcio/metabolismo , Señalización del Calcio/fisiología , Núcleo Celular/metabolismo , Mutación con Ganancia de Función , Regulación de la Expresión Génica de las Plantas , Células HEK293 , Humanos , Medicago truncatula/genética , Medicago truncatula/fisiología , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Nodulación de la Raíz de la Planta/genética , Nodulación de la Raíz de la Planta/fisiología , Raíces de Plantas/genética , Raíces de Plantas/fisiología , Simbiosis/fisiología
9.
BMC Plant Biol ; 22(1): 77, 2022 Feb 22.
Artículo en Inglés | MEDLINE | ID: mdl-35193491

RESUMEN

BACKGROUND: Structural variants (SVs) constitute a large proportion of the genomic variation that results in phenotypic variation in plants. However, they are still a largely unexplored feature in most plant genomes. Here, we present the whole-genome landscape of SVs between two model legume Medicago truncatula ecotypes-Jemalong A17 and R108- that have been extensively used in various legume biology studies. RESULTS: To catalogue SVs, we first resolved the previously published R108 genome assembly (R108 v1.0) to chromosome-scale using 124 × Hi-C data, resulting in a high-quality genome assembly. The inter-chromosomal reciprocal translocations between chromosomes 4 and 8 were confirmed by performing syntenic analysis between the two genomes. Combined with the Hi-C data, it appears that these translocation events had a significant effect on chromatin organization. Using both whole-genome and short-read alignments, we identified the genomic landscape of SVs between the two genomes, some of which may account for several phenotypic differences, including their differential responses to aluminum toxicity and iron deficiency, and the development of different anthocyanin leaf markings. We also found extensive SVs within the nodule-specific cysteine-rich gene family which encodes antimicrobial peptides essential for terminal bacteroid differentiation during nitrogen-fixing symbiosis. CONCLUSIONS: Our results provide a near-complete R108 genome assembly and the first genomic landscape of SVs obtained by comparing two M. truncatula ecotypes. This may provide valuable genomic resources for the functional and molecular research of legume biology in the future.


Asunto(s)
Cromatina/genética , Genoma de Planta , Medicago truncatula/genética , Cromosomas de las Plantas , Elementos Transponibles de ADN , Ecotipo , Eucromatina/química , Eucromatina/genética , Genes de Plantas , Heterocromatina/química , Heterocromatina/genética , Medicago truncatula/fisiología , Fijación del Nitrógeno/genética , Filogenia , Secuenciación Completa del Genoma
10.
Plant Physiol ; 188(1): 560-575, 2022 01 20.
Artículo en Inglés | MEDLINE | ID: mdl-34599592

RESUMEN

Most legumes can establish a symbiotic association with soil rhizobia that trigger the development of root nodules. These nodules host the rhizobia and allow them to fix nitrogen efficiently. The perception of bacterial lipo-chitooligosaccharides (LCOs) in the epidermis initiates a signaling cascade that allows rhizobial intracellular infection in the root and de-differentiation and activation of cell division that gives rise to the nodule. Thus, nodule organogenesis and rhizobial infection need to be coupled in space and time for successful nodulation. The plant hormone cytokinin (CK) contributes to the coordination of this process, acting as an essential positive regulator of nodule organogenesis. However, the temporal regulation of tissue-specific CK signaling and biosynthesis in response to LCOs or Sinorhizobium meliloti inoculation in Medicago truncatula remains poorly understood. In this study, using a fluorescence-based CK sensor (pTCSn::nls:tGFP), we performed a high-resolution tissue-specific temporal characterization of the sequential activation of CK response during root infection and nodule development in M. truncatula after inoculation with S. meliloti. Loss-of-function mutants of the CK-biosynthetic gene ISOPENTENYLTRANSFERASE 3 (IPT3) showed impairment of nodulation, suggesting that IPT3 is required for nodule development in M. truncatula. Simultaneous live imaging of pIPT3::nls:tdTOMATO and the CK sensor showed that IPT3 induction in the pericycle at the base of nodule primordium contributes to CK biosynthesis, which in turn promotes expression of positive regulators of nodule organogenesis in M. truncatula.


Asunto(s)
Transferasas Alquil y Aril/metabolismo , Citocininas/genética , Citocininas/metabolismo , Medicago truncatula/genética , Medicago truncatula/fisiología , Nodulación de la Raíz de la Planta/genética , Nódulos de las Raíces de las Plantas/metabolismo , Simbiosis/genética , Transferasas Alquil y Aril/genética , Regulación de la Expresión Génica de las Plantas , Genes de Plantas , Fijación del Nitrógeno/genética , Fijación del Nitrógeno/fisiología , Organogénesis/genética , Raíces de Plantas/genética , Raíces de Plantas/metabolismo , Nódulos de las Raíces de las Plantas/genética , Nódulos de las Raíces de las Plantas/crecimiento & desarrollo , Sinorhizobium meliloti/fisiología , Simbiosis/fisiología
11.
Plant J ; 108(6): 1679-1689, 2021 12.
Artículo en Inglés | MEDLINE | ID: mdl-34626033

RESUMEN

Leucine-rich repeat-receptor-like kinase (LRR-RLK) is a large subfamily of plant RLKs; however, its role in cold tolerance is still unknown. A novel cold tolerance LRR-RLK gene (MtCTLK1) in Medicago truncatula was identified using the transgenic lines overexpressing MtCTLK1 (MtCTLK1-OE) and mtctlk1 lines with Tnt1 retrotransposon insertion. Compared with the wild-type, MtCTLK1-OE lines had increased cold tolerance and mtctlk1 showed decreased cold tolerance. The impaired cold tolerance in mtctlk1 could be complemented by the transgenic expression of MtCTLK1 or its homolog MfCTLK1 from Medicago falcata. Antioxidant enzyme activities and proline accumulation as well as transcript levels of the associated genes were increased in response to cold, with higher levels in MtCTLK1-OE or lower levels in mtctlk1 lines as compared with wild type. C-Repeat-Binding Factors (CBFs) and CBF-dependent cold-responsive genes were also induced in response to cold, and higher transcript levels of CBFs and CBF-dependent cold-responsive genes were observed in MtCTLK1-OE lines whereas lower levels in mtctlk1 mutants. The results validate the role of MtCTLK1 or MfCTLK1 in the regulation of cold tolerance through the CBF pathway, antioxidant defense system and proline accumulation. It also provides a valuable gene for the molecular breeding program to improve cold tolerance in crops.


Asunto(s)
Respuesta al Choque por Frío/fisiología , Medicago truncatula/fisiología , Proteínas de Plantas/metabolismo , Prolina/metabolismo , Antioxidantes/metabolismo , Regulación de la Expresión Génica de las Plantas , Medicago truncatula/genética , Medicago truncatula/metabolismo , Redes y Vías Metabólicas , Proteínas de Plantas/genética , Plantas Modificadas Genéticamente , Retroelementos
12.
Int J Mol Sci ; 22(18)2021 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-34576120

RESUMEN

Cytochrome P450 monooxygenases (P450s) catalyze a great number of biochemical reactions and play vital roles in plant growth, development and secondary metabolism. As yet, the genome-scale investigation on P450s is still lacking in the model legume Medicago truncatula. In particular, whether and how many MtP450s are involved in drought and salt stresses for Medicago growth, development and yield remain unclear. In this study, a total of 346 MtP450 genes were identified and classified into 10 clans containing 48 families. Among them, sixty-one MtP450 genes pairs are tandem duplication events and 10 MtP450 genes are segmental duplication events. MtP450 genes within one family exhibit high conservation and specificity in intron-exon structure. Meanwhile, many Mt450 genes displayed tissue-specific expression pattern in various tissues. Specifically, the expression pattern of 204 Mt450 genes under drought/NaCl treatments were analyzed by using the weighted correlation network analysis (WGCNA). Among them, eight genes (CYP72A59v1, CYP74B4, CYP71AU56, CYP81E9, CYP71A31, CYP704G6, CYP76Y14, and CYP78A126), and six genes (CYP83D3, CYP76F70, CYP72A66, CYP76E1, CYP74C12, and CYP94A52) were found to be hub genes under drought/NaCl treatments, respectively. The expression levels of these selected hub genes could be induced, respectively, by drought/NaCl treatments, as validated by qPCR analyses, and most of these genes are involved in the secondary metabolism and fatty acid pathways. The genome-wide identification and co-expression analyses of M. truncatulaP450 superfamily genes established a gene atlas for a deep and systematic investigation of P450 genes in M. truncatula, and the selected drought-/salt-responsive genes could be utilized for further functional characterization and molecular breeding for resistance in legume crops.


Asunto(s)
Sistema Enzimático del Citocromo P-450/genética , Sequías , Regulación de la Expresión Génica de las Plantas , Genoma de Planta , Medicago truncatula/genética , Medicago truncatula/fisiología , Cloruro de Sodio/farmacología , Secuencias de Aminoácidos , Cromosomas de las Plantas/genética , Secuencia Conservada , Sistema Enzimático del Citocromo P-450/química , Sistema Enzimático del Citocromo P-450/metabolismo , Duplicación de Gen , Perfilación de la Expresión Génica , Regulación Enzimológica de la Expresión Génica/efectos de los fármacos , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Redes Reguladoras de Genes/efectos de los fármacos , Medicago truncatula/enzimología , Filogenia , Proteínas de Plantas/química , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Secuencias Reguladoras de Ácidos Nucleicos/genética , Sintenía/genética
13.
Plant Cell ; 33(11): 3470-3486, 2021 11 04.
Artículo en Inglés | MEDLINE | ID: mdl-34469578

RESUMEN

To acquire sufficient mineral nutrients such as phosphate (Pi) from the soil, most plants engage in symbiosis with arbuscular mycorrhizal (AM) fungi. Attracted by plant-secreted strigolactones (SLs), the fungi colonize the roots and form highly branched hyphal structures called arbuscules inside inner cortex cells. The host plant must control the different steps of this interaction to maintain its symbiotic nature. However, how plants sense the amount of Pi obtained from the fungus, and how this determines the arbuscule lifespan, are far from understood. Here, we show that Medicago truncatula SPX-domain containing proteins SPX1 and SPX3 regulate root Pi starvation responses, in part by interacting with PHOSPHATE RESPONSE REGULATOR2, as well as fungal colonization and arbuscule degradation. SPX1 and SPX3 are induced upon Pi starvation but become more restricted to arbuscule-containing cells upon the establishment of symbiosis. This induction in arbuscule-containing cells is associated with the presence of cis-regulatory AW-boxes and transcriptional regulation by the WRINKLED1-like transcription factor WRI5a. Under Pi-limiting conditions, SPX1 and SPX3 facilitate the expression of the SL biosynthesis gene DWARF27, which could help explain the increased fungal branching in response to root exudates. Later, in arbuscule-containing cells, SPX1 and SPX3 redundantly control arbuscule degradation. Thus, SPX proteins play important roles as phosphate sensors to maintain a beneficial AM symbiosis.


Asunto(s)
Homeostasis/genética , Medicago truncatula/fisiología , Micorrizas/fisiología , Fosfatos/fisiología , Proteínas de Plantas/genética , Medicago truncatula/genética , Proteínas de Plantas/metabolismo
14.
Plant J ; 108(4): 1069-1082, 2021 11.
Artículo en Inglés | MEDLINE | ID: mdl-34528312

RESUMEN

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.


Asunto(s)
Calmodulina/metabolismo , Regulación de la Expresión Génica de las Plantas , Medicago truncatula/genética , Rafinosa/metabolismo , Calmodulina/genética , Frío , Regulación hacia Abajo , Flores/genética , Flores/fisiología , Medicago truncatula/fisiología , Fenotipo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Estrés Fisiológico , Regulación hacia Arriba
15.
Plant Commun ; 2(3): 100183, 2021 05 10.
Artículo en Inglés | MEDLINE | ID: mdl-34027396

RESUMEN

Most legume plants can associate with diazotrophic soil bacteria called rhizobia, resulting in new root organs called nodules that enable N2 fixation. Nodulation is an energy-consuming process, and nodule number is tightly regulated by independent systemic signaling pathways controlled by CLE/SUNN and CEP/CRA2. Moreover, nitrate inhibits legume nodulation via local and systemic regulatory pathways. In Medicago truncatula, NLP1 plays important roles in nitrate-induced inhibition of nodulation, but the relationship between systemic and local pathways in mediating nodulation inhibition by nitrate is poorly understood. In this study, we found that nitrate induces CLE35 expression in an NLP1-dependent manner and that NLP1 binds directly to the CLE35 promoter to activate its expression. Grafting experiments revealed that the systemic control of nodule number involves negative regulation by SUNN and positive regulation by CRA2 in the shoot, and that NLP1's control of the inhibition of rhizobial infection, nodule development, and nitrogenase activity in response to nitrate is determined by the root. Unexpectedly, grafting experiments showed that loss of CRA2 in the root increases nodule number at inhibitory nitrate levels, probably because of CEP1/2 upregulation in the cra2 mutants, suggesting that CRA2 exerts active negative feedback regulation in the root.


Asunto(s)
Regulación de la Expresión Génica de las Plantas/fisiología , Medicago truncatula/fisiología , Nitratos/farmacología , Proteínas de Plantas/genética , Nodulación de la Raíz de la Planta/genética , Transducción de Señal/genética , Proteínas de Plantas/metabolismo , Nodulación de la Raíz de la Planta/efectos de los fármacos
16.
J Integr Plant Biol ; 63(8): 1537-1554, 2021 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-34009694

RESUMEN

Plants have a hierarchical circadian structure comprising multiple tissue-specific oscillators that operate at different speeds and regulate the expression of distinct sets of genes in different organs. However, the identity of the genes differentially regulated by the circadian clock in different organs, such as roots, and how their oscillations create functional specialization remain unclear. Here, we profiled the diurnal and circadian landscapes of the shoots and roots of Medicago truncatula and identified the conserved regulatory sequences contributing to transcriptome oscillations in each organ. We found that the light-dark cycles strongly affect the global transcriptome oscillation in roots, and many clock genes oscillate only in shoots. Moreover, many key genes involved in nitrogen fixation are regulated by circadian rhythms. Surprisingly, the root clock runs faster than the shoot clock, which is contrary to the hierarchical circadian structure showing a slow-paced root clock in both detached and intact Arabidopsis thaliana (L.) Heynh. roots. Our result provides important clues about the species-specific circadian regulatory mechanism, which is often overlooked, and possibly coordinates the timing between shoots and roots independent of the current prevailing model.


Asunto(s)
Relojes Circadianos/fisiología , Ritmo Circadiano/fisiología , Medicago truncatula/fisiología , Raíces de Plantas/fisiología , Relojes Circadianos/genética , Relojes Circadianos/efectos de la radiación , Ritmo Circadiano/genética , Ritmo Circadiano/efectos de la radiación , Regulación de la Expresión Génica de las Plantas/efectos de la radiación , Genes de Plantas , Luz , Medicago truncatula/genética , Medicago truncatula/efectos de la radiación , Fijación del Nitrógeno/genética , Fijación del Nitrógeno/efectos de la radiación , Especificidad de Órganos/genética , Especificidad de Órganos/efectos de la radiación , Raíces de Plantas/genética , Raíces de Plantas/efectos de la radiación , Brotes de la Planta/genética , Brotes de la Planta/fisiología , Brotes de la Planta/efectos de la radiación , Regiones Promotoras Genéticas/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , Especificidad de la Especie , Transcripción Genética/efectos de la radiación , Transcriptoma/genética
17.
Plant Cell Environ ; 44(6): 1908-1920, 2021 06.
Artículo en Inglés | MEDLINE | ID: mdl-33797764

RESUMEN

Yellow Stripe-Like (YSL) proteins are a family of plant transporters that are typically involved in transition metal homeostasis. Three of the four YSL clades (I, II and IV) transport metals complexed with the non-proteinogenic amino acid nicotianamine or its derivatives. No such capability has been shown for any member of clade III, but the link between these YSLs and metal homeostasis could be masked by functional redundancy. We studied the role of the clade III YSL protein MtSYL7 in Medicago truncatula nodules. MtYSL7, which encodes a plasma membrane-bound protein, is mainly expressed in the pericycle and cortex cells of the root nodules. Yeast complementation assays revealed that MtSYL7 can transport short peptides. M. truncatula transposon insertion mutants with decreased expression of MtYSL7 had lower nitrogen fixation rates and showed reduced plant growth whether grown in symbiosis with rhizobia or not. YSL7 mutants accumulated more copper and iron in the nodules, which is likely to result from the increased expression of iron uptake and delivery genes in roots. Taken together, these data suggest that MtYSL7 plays an important role in the transition metal homeostasis of nodules and symbiotic nitrogen fixation.


Asunto(s)
Medicago truncatula/fisiología , Fijación del Nitrógeno/fisiología , Proteínas de Plantas/metabolismo , Membrana Celular/metabolismo , Regulación de la Expresión Génica de las Plantas , Mutación , Proteínas de Plantas/genética , Raíces de Plantas/genética , Plantas Modificadas Genéticamente , Transporte de Proteínas , Rhizobium , Nódulos de las Raíces de las Plantas/genética , Nódulos de las Raíces de las Plantas/metabolismo , Simbiosis
19.
Plant J ; 106(5): 1298-1311, 2021 06.
Artículo en Inglés | MEDLINE | ID: mdl-33733554

RESUMEN

As the frequency of extreme environmental events is expected to increase with climate change, identifying candidate genes for stabilizing the protein composition of legume seeds or optimizing this in a given environment is increasingly important. To elucidate the genetic determinants of seed protein plasticity, major seed proteins from 200 ecotypes of Medicago truncatula grown in four contrasting environments were quantified after one-dimensional electrophoresis. The plasticity index of these proteins was recorded for each genotype as the slope of Finlay and Wilkinson's regression and then used for genome-wide association studies (GWASs), enabling the identification of candidate genes for determining this plasticity. This list was enriched in genes related to transcription, DNA repair and signal transduction, with many of them being stress responsive. Other over-represented genes were related to sulfur and aspartate family pathways leading to the synthesis of the nutritionally essential amino acids methionine and lysine. By placing these genes in metabolic pathways, and using a M. truncatula mutant impaired in regenerating methionine from S-methylmethionine, we discovered that methionine recycling pathways are major contributors to globulin composition establishment and plasticity. These data provide a unique resource of genes that can be targeted to mitigate negative impacts of environmental stresses on seed protein composition.


Asunto(s)
Medicago truncatula/genética , Proteínas de Almacenamiento de Semillas/metabolismo , Estudio de Asociación del Genoma Completo , Genotipo , Globulinas/genética , Globulinas/metabolismo , Medicago truncatula/fisiología , Metionina/metabolismo , Mutación , Fenotipo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Proteínas de Almacenamiento de Semillas/genética , Semillas/genética , Semillas/fisiología , Estrés Fisiológico , Vitamina U/metabolismo
20.
Genes (Basel) ; 11(11)2020 11 23.
Artículo en Inglés | MEDLINE | ID: mdl-33238556

RESUMEN

The trihelix transcription factor (GT) family is widely involved in regulating plant growth and development, and most importantly, responding to various abiotic stresses. Our study first reported the genome-wide identification and analysis of GT family genes in Medicago truncatula. Overall, 38 trihelix genes were identified in the M. truncatula genome and were classified into five subfamilies (GT-1, GT-2, SH4, GTγ and SIP1). We systematically analyzed the phylogenetic relationship, chromosomal distribution, tandem and segmental duplication events, gene structures and conserved motifs of MtGTs. Syntenic analysis revealed that trihelix family genes in M. truncatula had the most collinearity relationship with those in soybean followed by alfalfa, but very little collinearity with those in the maize and rice. Additionally, tissue-specific expression analysis of trihelix family genes suggested that they played various roles in the growth and development of specific tissues in M. truncatula. Moreover, the expression of some MtGT genes, such as MtGT19, MtGT20, MtGT22, and MtGT33, was dramatically induced by drought, salt, and ABA treatments, illustrating their vital roles in response to abiotic stresses. These findings are helpful for improving the comprehensive understanding of trihelix family; additionally, the study provides candidate genes for achieving the genetic improvement of stress resistance in legumes.


Asunto(s)
Medicago truncatula/genética , Proteínas de Plantas/genética , Estrés Fisiológico/genética , Factores de Transcripción/genética , Ácido Abscísico/farmacología , Mapeo Cromosómico , Evolución Molecular , Duplicación de Gen , Perfilación de la Expresión Génica , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Genoma de Planta , Estudio de Asociación del Genoma Completo , Medicago truncatula/efectos de los fármacos , Medicago truncatula/fisiología , Familia de Multigenes , Oryza/genética , Filogenia
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