RESUMEN
In response to biotic stress, plants produce suites of highly modified fatty acids that bear unusual chemical functionalities. Despite their chemical complexity and proposed roles in pathogen defense, little is known about the biosynthesis of decorated fatty acids in plants. Falcarindiol is a prototypical acetylenic lipid present in carrot, tomato, and celery that inhibits growth of fungi and human cancer cell lines. Using a combination of untargeted metabolomics and RNA sequencing, we discovered a biosynthetic gene cluster in tomato (Solanum lycopersicum) required for falcarindiol production. By reconstituting initial biosynthetic steps in a heterologous host and generating transgenic pathway mutants in tomato, we demonstrate a direct role of the cluster in falcarindiol biosynthesis and resistance to fungal and bacterial pathogens in tomato leaves. This work reveals a mechanism by which plants sculpt their lipid pool in response to pathogens and provides critical insight into the complex biochemistry of alkynyl lipid production.
Asunto(s)
Diinos/metabolismo , Ácidos Grasos/biosíntesis , Alcoholes Grasos/metabolismo , Solanum lycopersicum/genética , Resistencia a la Enfermedad/genética , Diinos/química , Ácidos Grasos/metabolismo , Alcoholes Grasos/química , Regulación de la Expresión Génica de las Plantas/genética , Metabolómica , Familia de Multigenes/genética , Enfermedades de las Plantas/microbiología , Hojas de la Planta/metabolismo , Proteínas de Plantas/metabolismo , Plantas Modificadas Genéticamente , Estrés Fisiológico/genéticaRESUMEN
Following a previous microbial inoculation, plants can induce broad-spectrum immunity to pathogen infection, a phenomenon known as systemic acquired resistance (SAR). SAR establishment in Arabidopsis thaliana is regulated by the Lys catabolite pipecolic acid (Pip) and flavin-dependent-monooxygenase1 (FMO1). Here, we show that elevated Pip is sufficient to induce an FMO1-dependent transcriptional reprogramming of leaves that is reminiscent of SAR. In planta and in vitro analyses demonstrate that FMO1 functions as a pipecolate N-hydroxylase, catalyzing the biochemical conversion of Pip to N-hydroxypipecolic acid (NHP). NHP systemically accumulates in plants after microbial attack. When exogenously applied, it overrides the defect of NHP-deficient fmo1 in acquired resistance and acts as a potent inducer of plant immunity to bacterial and oomycete infection. Our work has identified a pathogen-inducible L-Lys catabolic pathway in plants that generates the N-hydroxylated amino acid NHP as a critical regulator of systemic acquired resistance to pathogen infection.
Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Oxigenasas/metabolismo , Ácidos Pipecólicos/metabolismo , Inmunidad de la Planta/efectos de los fármacos , Arabidopsis/enzimología , Arabidopsis/inmunología , Proteínas de Arabidopsis/genética , Cromatografía de Gases y Espectrometría de Masas , Lisina/metabolismo , Oomicetos/patogenicidad , Oxigenasas/genética , Ácidos Pipecólicos/análisis , Ácidos Pipecólicos/farmacología , Hojas de la Planta/enzimología , Hojas de la Planta/inmunología , Hojas de la Planta/metabolismo , Pseudomonas syringae/patogenicidad , Transaminasas/genética , Transaminasas/metabolismoRESUMEN
Increasing planting density is a key strategy for enhancing maize yields1-3. An ideotype for dense planting requires a 'smart canopy' with leaf angles at different canopy layers differentially optimized to maximize light interception and photosynthesis4-6, among other features. Here we identified leaf angle architecture of smart canopy 1 (lac1), a natural mutant with upright upper leaves, less erect middle leaves and relatively flat lower leaves. lac1 has improved photosynthetic capacity and attenuated responses to shade under dense planting. lac1 encodes a brassinosteroid C-22 hydroxylase that predominantly regulates upper leaf angle. Phytochrome A photoreceptors accumulate in shade and interact with the transcription factor RAVL1 to promote its degradation via the 26S proteasome, thereby inhibiting activation of lac1 by RAVL1 and decreasing brassinosteroid levels. This ultimately decreases upper leaf angle in dense fields. Large-scale field trials demonstrate that lac1 boosts maize yields under high planting densities. To quickly introduce lac1 into breeding germplasm, we transformed a haploid inducer and recovered homozygous lac1 edits from 20 diverse inbred lines. The tested doubled haploids uniformly acquired smart-canopy-like plant architecture. We provide an important target and an accelerated strategy for developing high-density-tolerant cultivars, with lac1 serving as a genetic chassis for further engineering of a smart canopy in maize.
Asunto(s)
Brasinoesteroides , Fotosíntesis , Hojas de la Planta , Zea mays , Zea mays/crecimiento & desarrollo , Zea mays/genética , Hojas de la Planta/metabolismo , Hojas de la Planta/crecimiento & desarrollo , Brasinoesteroides/metabolismo , Fitocromo A/metabolismo , Fitocromo A/genética , Complejo de la Endopetidasa Proteasomal/metabolismo , Haploidia , Homocigoto , Mutación , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , LuzRESUMEN
As the climate changes, warmer spring temperatures are causing earlier leaf-out1-3 and commencement of CO2 uptake1,3 in temperate deciduous forests, resulting in a tendency towards increased growing season length3 and annual CO2 uptake1,3-7. However, less is known about how spring temperatures affect tree stem growth8,9, which sequesters carbon in wood that has a long residence time in the ecosystem10,11. Here we show that warmer spring temperatures shifted stem diameter growth of deciduous trees earlier but had no consistent effect on peak growing season length, maximum growth rates, or annual growth, using dendrometer band measurements from 440 trees across two forests. The latter finding was confirmed on the centennial scale by 207 tree-ring chronologies from 108 forests across eastern North America, where annual ring width was far more sensitive to temperatures during the peak growing season than in the spring. These findings imply that any extra CO2 uptake in years with warmer spring temperatures4,5 does not significantly contribute to increased sequestration in long-lived woody stem biomass. Rather, contradicting projections from global carbon cycle models1,12, our empirical results imply that warming spring temperatures are unlikely to increase woody productivity enough to strengthen the long-term CO2 sink of temperate deciduous forests.
Asunto(s)
Calentamiento Global , Estaciones del Año , Temperatura , Árboles , Aclimatación , Biomasa , Dióxido de Carbono/metabolismo , Secuestro de Carbono , Modelos Climáticos , Bosques , Calentamiento Global/estadística & datos numéricos , América del Norte , Hojas de la Planta/crecimiento & desarrollo , Hojas de la Planta/metabolismo , Tallos de la Planta/crecimiento & desarrollo , Tallos de la Planta/metabolismo , Factores de Tiempo , Árboles/anatomía & histología , Árboles/clasificación , Árboles/crecimiento & desarrollo , Árboles/metabolismo , Madera/crecimiento & desarrollo , Madera/metabolismoRESUMEN
Selective partitioning of amino acids among organelles, cells, tissues, and organs is essential for cellular metabolism and plant growth. Nitrogen assimilation into glutamine and glutamate and de novo biosynthesis of most protein amino acids occur in chloroplasts; therefore, various transport mechanisms must exist to accommodate their directional efflux from the stroma to the cytosol and feed the amino acids into the extraplastidial metabolic and long-distance transport pathways. Yet, Arabidopsis (Arabidopsis thaliana) transporters functioning in plastidial export of amino acids remained undiscovered. Here, USUALLY MULTIPLE ACIDS MOVE IN AND OUT TRANSPORTER 44 (UMAMIT44) was identified and shown to function in glutamate export from Arabidopsis chloroplasts. UMAMIT44 controls glutamate homeostasis within and outside of chloroplasts and influences nitrogen partitioning from leaves to sinks. Glutamate imbalances in chloroplasts and leaves of umamit44 mutants impact cellular redox state, nitrogen and carbon metabolism, and amino acid (AA) and sucrose supply of growing sinks, leading to negative effects on plant growth. Nonetheless, the mutant lines adjust to some extent by upregulating alternative pathways for glutamate synthesis outside the plastids and by mitigating oxidative stress through the production of other amino acids and antioxidants. Overall, this study establishes that the role of UMAMIT44 in glutamate export from chloroplasts is vital for controlling nitrogen availability within source leaf cells and for sink nutrition, with an impact on growth and seed yield.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Ácido Glutámico , Cloroplastos/metabolismo , Proteínas de Transporte de Membrana/metabolismo , Aminoácidos/metabolismo , Hojas de la Planta/metabolismo , Nitrógeno/metabolismoRESUMEN
Cucumber (Cucumis sativus, Cs) tendrils are slender vegetative organs that typically require manual removal to ensure orderly growth during greenhouse cultivation. Here, we identified cucumber tendril-less (tl), a Tnt1 retrotransposon-induced insertion mutant lacking tendrils. Map-based cloning identified the mutated gene, CsaV3_3G003590, which we designated as CsTL, which is homologous to Arabidopsis thaliana LATERAL SUPPRESSOR (AtLAS). Knocking out CsTL repressed tendril formation but did not affect branch initiation, whereas overexpression (OE) of CsTL resulted in the formation of two or more tendrils in one leaf axil. Although expression of two cucumber genes regulating tendril formation, Tendril (CsTEN) and Unusual Floral Organs (CsUFO), was significantly decreased in CsTL knockout lines, these two genes were not direct downstream targets of CsTL. Instead, CsTL physically interacted with CsTEN, an interaction that further enhanced CsTEN-mediated expression of CsUFO. In Arabidopsis, the CsTL homolog AtLAS acts upstream of REVOLUTA (REV) to regulate branch initiation. Knocking out cucumber CsREV inhibited branch formation without affecting tendril initiation. Furthermore, genomic regions containing CsTL and AtLAS were not syntenic between the cucumber and Arabidopsis genomes, whereas REV orthologs were found on a shared syntenic block. Our results revealed not only that cucumber CsTL possesses a divergent function in promoting tendril formation but also that CsREV retains its conserved function in shoot branching.
Asunto(s)
Arabidopsis , Cucumis sativus , Regulación de la Expresión Génica de las Plantas , Proteínas de Plantas , Factores de Transcripción , Cucumis sativus/genética , Cucumis sativus/crecimiento & desarrollo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Arabidopsis/crecimiento & desarrollo , Plantas Modificadas Genéticamente , Hojas de la Planta/genética , Hojas de la Planta/metabolismo , Hojas de la Planta/crecimiento & desarrolloRESUMEN
The milestone of compound leaf development is the generation of separate leaflet primordia during the early stages, which involves two linked but distinct morphogenetic events: leaflet initiation and boundary establishment for leaflet separation. Although some progress in understanding the regulatory pathways for each event have been made, it is unclear how they are intrinsically coordinated. Here, we identify the PINNATE-LIKE PENTAFOLIATA2 (PINNA2) gene encoding a newly identified GRAS transcription factor in Medicago truncatula. PINNA2 transcripts are preferentially detected at organ boundaries. Its loss-of-function mutations convert trifoliate leaves into a pinnate pentafoliate pattern. PINNA2 directly binds to the promoter region of the LEAFY orthologue SINGLE LEAFLET1 (SGL1), which encodes a key positive regulator of leaflet initiation, and downregulates its expression. Further analysis revealed that PINNA2 synergizes with two other repressors of SGL1 expression, the BEL1-like homeodomain protein PINNA1 and the C2H2 zinc finger protein PALMATE-LIKE PENTAFOLIATA1 (PALM1), to precisely define the spatiotemporal expression of SGL1 in compound leaf primordia, thereby maintaining a proper pattern of leaflet initiation. Moreover, we showed that the enriched expression of PINNA2 at the leaflet-to-leaflet boundaries is positively regulated by the boundary-specific gene MtNAM, which is essential for leaflet boundary formation. Together, these results unveil a pivotal role of the boundary-expressed transcription factor PINNA2 in regulating leaflet initiation, providing molecular insights into the coordination of intricate developmental processes underlying compound leaf pattern formation.
Asunto(s)
Regulación de la Expresión Génica de las Plantas , Medicago truncatula , Hojas de la Planta , Medicago truncatula/genética , Medicago truncatula/crecimiento & desarrollo , Medicago truncatula/metabolismo , Morfogénesis/genética , Hojas de la Planta/genética , Hojas de la Planta/crecimiento & desarrollo , Hojas de la Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Modificadas Genéticamente , Regiones Promotoras Genéticas/genética , Factores de Transcripción/metabolismo , Factores de Transcripción/genéticaRESUMEN
Carotenoids are essential for photosynthesis and photoprotection. Plants must evolve multifaceted regulatory mechanisms to control carotenoid biosynthesis. However, the regulatory mechanisms and the regulators conserved among plant species remain elusive. Phytoene synthase (PSY) catalyzes the highly regulated step of carotenogenesis and geranylgeranyl diphosphate synthase (GGPPS) acts as a hub to interact with GGPP-utilizing enzymes for the synthesis of specific downstream isoprenoids. Here, we report a function of Nudix hydrolase 23 (NUDX23), a Nudix domain-containing protein, in post-translational regulation of PSY and GGPPS for carotenoid biosynthesis. NUDX23 expresses highly in Arabidopsis (Arabidopsis thaliana) leaves. Overexpression of NUDX23 significantly increases PSY and GGPPS protein levels and carotenoid production, whereas knockout of NUDX23 dramatically reduces their abundances and carotenoid accumulation in Arabidopsis. NUDX23 regulates carotenoid biosynthesis via direct interactions with PSY and GGPPS in chloroplasts, which enhances PSY and GGPPS protein stability in a large PSY-GGPPS enzyme complex. NUDX23 was found to co-migrate with PSY and GGPPS proteins and to be required for the enzyme complex assembly. Our findings uncover a regulatory mechanism underlying carotenoid biosynthesis in plants and offer promising genetic tools for developing carotenoid-enriched food crops.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Carotenoides , Regulación de la Expresión Génica de las Plantas , Carotenoides/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Hidrolasas Nudix , Cloroplastos/metabolismo , Geranilgeranil-Difosfato Geranilgeraniltransferasa/metabolismo , Geranilgeranil-Difosfato Geranilgeraniltransferasa/genética , Farnesiltransferasa/metabolismo , Farnesiltransferasa/genética , Pirofosfatasas/metabolismo , Pirofosfatasas/genética , Procesamiento Proteico-Postraduccional , Plantas Modificadas Genéticamente , Hojas de la Planta/metabolismo , Hojas de la Planta/genéticaRESUMEN
Shoot branching affects plant architecture. In strawberry (Fragaria L.), short branches (crowns) develop from dormant axillary buds to form inflorescences and flowers. While this developmental transition contributes greatly to perenniality and yield in strawberry, its regulatory mechanism remains unclear and understudied. In the woodland strawberry (Fragaria vesca), we identified and characterized 2 independent mutants showing more crowns. Both mutant alleles reside in FveMYB117a, a R2R3-MYB transcription factor gene highly expressed in shoot apical meristems, axillary buds, and young leaves. Transcriptome analysis revealed that the expression of several cytokinin pathway genes was altered in the fvemyb117a mutant. Consistently, active cytokinins were significantly increased in the axillary buds of the fvemyb117a mutant. Exogenous application of cytokinin enhanced crown outgrowth in the wild type, whereas the cytokinin inhibitors suppressed crown outgrowth in the fvemyb117a mutant. FveMYB117a binds directly to the promoters of the cytokinin homeostasis genes FveIPT2 encoding an isopentenyltransferase and FveCKX1 encoding a cytokinin oxidase to regulate their expression. Conversely, the type-B Arabidopsis response regulators FveARR1 and FveARR2b can directly inhibit the expression of FveMYB117a, indicative of a negative feedback regulation. In conclusion, we identified FveMYB117a as a key repressor of crown outgrowth by inhibiting cytokinin accumulation and provide a mechanistic basis for bud fate transition in an herbaceous perennial plant.
Asunto(s)
Citocininas , Fragaria , Regulación de la Expresión Génica de las Plantas , Proteínas de Plantas , Factores de Transcripción , Citocininas/metabolismo , Fragaria/genética , Fragaria/crecimiento & desarrollo , Fragaria/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Factores de Transcripción/metabolismo , Factores de Transcripción/genética , Homeostasis , Mutación , Hojas de la Planta/metabolismo , Hojas de la Planta/genética , Hojas de la Planta/crecimiento & desarrollo , Brotes de la Planta/crecimiento & desarrollo , Brotes de la Planta/genética , Brotes de la Planta/metabolismoRESUMEN
Plants have an astonishing ability to regenerate new organs after wounding. Here, we report that the wound-inducible transcription factor ENHANCER OF SHOOT REGENERATION1 (ESR1) has a dual mode of action in activating ANTHRANILATE SYNTHASE ALPHA SUBUNIT1 (ASA1) expression to ensure auxin-dependent de novo root organogenesis locally at wound sites of Arabidopsis (Arabidopsis thaliana) leaf explants. In the first mode, ESR1 interacts with HISTONE DEACETYLASE6 (HDA6), and the ESR1-HDA6 complex directly binds to the JASMONATE-ZIM DOMAIN5 (JAZ5) locus, inhibiting JAZ5 expression through histone H3 deacetylation. As JAZ5 interferes with the action of ETHYLENE RESPONSE FACTOR109 (ERF109), the transcriptional repression of JAZ5 at the wound site allows ERF109 to activate ASA1 expression. In the second mode, the ESR1 transcriptional activator directly binds to the ASA1 promoter to enhance its expression. Overall, our findings indicate that the dual biochemical function of ESR1, which specifically occurs near wound sites of leaf explants, maximizes local auxin biosynthesis and de novo root organogenesis in Arabidopsis.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Regulación de la Expresión Génica de las Plantas , Organogénesis de las Plantas , Raíces de Plantas , Factores de Transcripción , Arabidopsis/genética , Arabidopsis/crecimiento & desarrollo , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Histona Desacetilasas/metabolismo , Histona Desacetilasas/genética , Ácidos Indolacéticos/metabolismo , Organogénesis de las Plantas/genética , Hojas de la Planta/genética , Hojas de la Planta/metabolismo , Hojas de la Planta/crecimiento & desarrollo , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/genética , Plantas Modificadas Genéticamente , Regiones Promotoras Genéticas/genética , Factores de Transcripción/metabolismo , Factores de Transcripción/genéticaRESUMEN
MicroRNAs (miRNAs) are processed from primary transcripts that contain partially self-complementary foldbacks. As in animals, the core microprocessor in plants is a Dicer protein, DICER-LIKE1 (DCL1). Processing accuracy and strand selection is greatly enhanced through the RNA binding protein HYPONASTIC LEAVES 1 (HYL1) and the zinc finger protein SERRATE (SE). We have combined a luciferase-based genetic screen with whole-genome sequencing for rapid identification of new regulators of miRNA biogenesis and action. Among the first six mutants analyzed were three alleles of C-TERMINAL DOMAIN PHOSPHATASE-LIKE 1 (CPL1)/FIERY2 (FRY2). In the miRNA processing complex, SE functions as a scaffold to mediate CPL1 interaction with HYL1, which needs to be dephosphorylated for optimal activity. In the absence of CPL1, HYL1 dephosphorylation and hence accurate processing and strand selection from miRNA duplexes are compromised. Our findings thus define a new regulatory step in plant miRNA biogenesis.
Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , MicroARNs/metabolismo , Fosfoproteínas Fosfatasas/metabolismo , Procesamiento Postranscripcional del ARN , ARN de Planta/metabolismo , Proteínas de Unión al ARN/metabolismo , Factores de Transcripción/metabolismo , Proteínas de Unión al Calcio/metabolismo , Péptidos y Proteínas de Señalización Intercelular/metabolismo , Proteínas de la Membrana/metabolismo , Fosforilación , Hojas de la Planta/metabolismo , Proteínas de Plantas/metabolismo , Proteínas Serrate-Jagged , Nicotiana/metabolismoRESUMEN
Symbiotic N2-fixing microorganisms have a crucial role in the assimilation of nitrogen by eukaryotes in nitrogen-limited environments1-3. Particularly among land plants, N2-fixing symbionts occur in a variety of distantly related plant lineages and often involve an intimate association between host and symbiont2,4. Descriptions of such intimate symbioses are lacking for seagrasses, which evolved around 100 million years ago from terrestrial flowering plants that migrated back to the sea5. Here we describe an N2-fixing symbiont, 'Candidatus Celerinatantimonas neptuna', that lives inside seagrass root tissue, where it provides ammonia and amino acids to its host in exchange for sugars. As such, this symbiosis is reminiscent of terrestrial N2-fixing plant symbioses. The symbiosis between Ca. C. neptuna and its host Posidonia oceanica enables highly productive seagrass meadows to thrive in the nitrogen-limited Mediterranean Sea. Relatives of Ca. C. neptuna occur worldwide in coastal ecosystems, in which they may form similar symbioses with other seagrasses and saltmarsh plants. Just like N2-fixing microorganisms might have aided the colonization of nitrogen-poor soils by early land plants6, the ancestors of Ca. C. neptuna and its relatives probably enabled flowering plants to invade nitrogen-poor marine habitats, where they formed extremely efficient blue carbon ecosystems7.
Asunto(s)
Alismatales/microbiología , Organismos Acuáticos/metabolismo , Bacterias/metabolismo , Fijación del Nitrógeno , Nitrógeno/metabolismo , Simbiosis , Alismatales/metabolismo , Aminoácidos/metabolismo , Amoníaco/metabolismo , Organismos Acuáticos/microbiología , Ecosistema , Endófitos/metabolismo , Mar Mediterráneo , Hojas de la Planta/metabolismo , Raíces de Plantas/metabolismo , Raíces de Plantas/microbiologíaRESUMEN
One of the most notable ecological trends-described more than 2,300 years ago by Theophrastus-is the association of small leaves with dry and cold climates, which has recently been recognized for eudicotyledonous plants at a global scale1-3. For eudicotyledons, this pattern has been attributed to the fact that small leaves have a thinner boundary layer that helps to avoid extreme leaf temperatures4 and their leaf development results in vein traits that improve water transport under cold or dry climates5,6. However, the global distribution of leaf size and its adaptive basis have not been tested in the grasses, which represent a diverse lineage that is distinct in leaf morphology and that contributes 33% of terrestrial primary productivity (including the bulk of crop production)7. Here we demonstrate that grasses have shorter and narrower leaves under colder and drier climates worldwide. We show that small grass leaves have thermal advantages and vein development that contrast with those of eudicotyledons, but that also explain the abundance of small leaves in cold and dry climates. The worldwide distribution of leaf size in grasses exemplifies how biophysical and developmental processes result in convergence across major lineages in adaptation to climate globally, and highlights the importance of leaf size and venation architecture for grass performance in past, present and future ecosystems.
Asunto(s)
Aclimatación , Cambio Climático , Hojas de la Planta/crecimiento & desarrollo , Poaceae/crecimiento & desarrollo , Agua/metabolismo , Xilema/crecimiento & desarrollo , Fenómenos Biofísicos , Clima , Frío , Sequías , Hojas de la Planta/anatomía & histología , Hojas de la Planta/metabolismo , Poaceae/anatomía & histología , Poaceae/metabolismo , Xilema/anatomía & histología , Xilema/metabolismoRESUMEN
Decomposition of dead organic matter is fundamental to carbon (C) and nutrient cycling in terrestrial ecosystems, influencing C fluxes from the biosphere to the atmosphere. Theory predicts and evidence strongly supports that the availability of nitrogen (N) limits litter decomposition. Positive relationships between substrate N concentrations and decomposition have been embedded into ecosystem models. This decomposition paradigm, however, relies on data mostly from short-term studies analyzing controls on early-stage decomposition. We present evidence from three independent long-term decomposition investigations demonstrating that the positive N-decomposition relationship is reversed and becomes negative during later stages of decomposition. First, in a 10-y decomposition experiment across 62 woody species in a temperate forest, leaf litter with higher N concentrations exhibited faster initial decomposition rates but ended up a larger recalcitrant fraction decomposing at a near-zero rate. Second, in a 5-y N-enrichment experiment of two tree species, leaves with experimentally enriched N concentrations had faster decomposition initial rates but ultimately accumulated large slowly decomposing fractions. Measures of amino sugars on harvested litter in two experiments indicated that greater accumulation of microbial residues in N-rich substrates likely contributed to larger slowly decomposing fractions. Finally, a database of 437 measurements from 120 species in 45 boreal and temperate forest sites confirmed that higher N concentrations were associated with a larger slowly decomposing fraction. These results challenge the current treatment of interactions between N and decomposition in many ecosystems and Earth system models and suggest that even the best-supported short-term controls of biogeochemical processes might not predict long-term controls.
Asunto(s)
Bosques , Nitrógeno , Hojas de la Planta , Árboles , Nitrógeno/metabolismo , Nitrógeno/química , Hojas de la Planta/química , Hojas de la Planta/metabolismo , Árboles/metabolismo , Carbono/metabolismo , Carbono/química , Ecosistema , Taiga , Ciclo del CarbonoRESUMEN
Leaves of flowering plants are characterized by diverse venation patterns. Patterning begins with the selection of vein-forming procambial initial cells from within the ground meristem of a developing leaf, a process which is considered to be auxin-dependent, and continues until veins are anatomically differentiated with functional xylem and phloem. At present, the mechanisms responsible for leaf venation patterning are primarily characterized in the model eudicot Arabidopsis thaliana which displays a reticulate venation network. However, evidence suggests that vein development may proceed via a different mechanism in monocot leaves where venation patterning is parallel. Here, we employed Molecular Cartography, a multiplexed in situ hybridization technique, to analyze the spatiotemporal localization of a subset of auxin-related genes and candidate regulators of vein patterning in maize leaves. We show how different combinations of auxin influx and efflux transporters are recruited during leaf and vein specification and how major and minor vein ranks develop with distinct identities. The localization of the procambial marker PIN1a and the spatial arrangement of procambial initial cells that give rise to major and minor vein ranks further suggests that vein spacing is prepatterned across the medio-lateral leaf axis prior to accumulation of the PIN1a auxin transporter. In contrast, patterning in the adaxial-abaxial axis occurs progressively, with markers of xylem and phloem gradually becoming polarized as differentiation proceeds. Collectively, our data suggest that both lineage- and position-based mechanisms may underpin vein patterning in maize leaves.
Asunto(s)
Hibridación in Situ , Ácidos Indolacéticos , Hojas de la Planta , Zea mays , Zea mays/genética , Zea mays/crecimiento & desarrollo , Hojas de la Planta/crecimiento & desarrollo , Hojas de la Planta/metabolismo , Hojas de la Planta/genética , Ácidos Indolacéticos/metabolismo , Regulación de la Expresión Génica de las Plantas , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Xilema/metabolismo , Xilema/crecimiento & desarrollo , Xilema/citología , Xilema/genéticaRESUMEN
Leaf wounding triggers rapid long-range electrical signaling that initiates systemic defense responses to protect the plants from further attack. In Arabidopsis, this process largely depends on clade three GLUTAMATE RECEPTOR-LIKE (GLR) genes GLR3.3 and GLR3.6. In the cellular context, phloem sieve elements and xylem contact cells where GLRs were mostly present are implicated in the signaling events. In spite of that, the spatial requirements of different leaf cell types for leaf-to-leaf signaling remain poorly investigated. In this study, we dissected cell-type-specific long-distance wound signaling mediated by GLR3s and showed that phloem companion cells are critical in shaping the functions of GLR3.3 and GLR3.6 in the signaling pathway. GLR3.3-mediated response is phloem-specific, during which, GLR3.3 has to be renewed from companion cells to allow its function in sieve elements. GLR3.6 functions dually in ectopic phloem companion cells, in addition to xylem contact cells. Furthermore, the action of GLR3.6 in phloem is independent of its paralog GLR3.3 and probably requires synthesis of GLR3.6 from xylem contact cells. Overall, our work highlights that the phloem companion cell is crucial for both GLRs in controlling leaf-to-leaf electrical signaling.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Floema , Hojas de la Planta , Transducción de Señal , Hojas de la Planta/metabolismo , Arabidopsis/metabolismo , Arabidopsis/genética , Arabidopsis/fisiología , Floema/metabolismo , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Receptores de Glutamato/metabolismo , Xilema/metabolismo , Regulación de la Expresión Génica de las PlantasRESUMEN
Low phosphate (Pi) availability decreases photosynthesis, with phosphate limitation of photosynthesis occurring particularly during grain filling of cereal crops; however, effective genetic solutions remain to be established. We previously discovered that rice phosphate transporter OsPHO1;2 controls seed (sink) development through Pi reallocation during grain filling. Here, we find that OsPHO1;2 regulates Pi homeostasis and thus photosynthesis in leaves (source). Loss-of-function of OsPHO1;2 decreased Pi levels in leaves, leading to decreased photosynthetic electron transport activity, CO2 assimilation rate, and early occurrence of phosphate-limited photosynthesis. Interestingly, ectopic expression of OsPHO1;2 greatly increased Pi availability, and thereby, increased photosynthetic rate in leaves during grain filling, contributing to increased yield. This was supported by the effect of foliar Pi application. Moreover, analysis of core rice germplasm resources revealed that higher OsPHO1;2 expression was associated with enhanced photosynthesis and yield potential compared to those with lower expression. These findings reveal that phosphate-limitation of photosynthesis can be relieved via a genetic approach, and the OsPHO1;2 gene can be employed to reinforce crop breeding strategies for achieving higher photosynthetic efficiency.
Asunto(s)
Oryza , Fosfatos , Fotosíntesis , Oryza/genética , Oryza/metabolismo , Oryza/crecimiento & desarrollo , Fosfatos/metabolismo , Hojas de la Planta/metabolismo , Hojas de la Planta/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Regulación de la Expresión Génica de las Plantas , Proteínas de Transporte de Fosfato/genética , Proteínas de Transporte de Fosfato/metabolismo , Plantas Modificadas GenéticamenteRESUMEN
How tissue-level information encoded by fields of regulatory gene activity is translated into the patterns of cell polarity and growth that generate the diverse shapes of different species remains poorly understood. Here, we investigate this problem in the case of leaf shape differences between Arabidopsis thaliana, which has simple leaves, and its relative Cardamine hirsuta that has complex leaves divided into leaflets. We show that patterned expression of the transcription factor CUP-SHAPED COTYLEDON1 in C. hirsuta (ChCUC1) is a key determinant of leaf shape differences between the two species. Through inducible genetic perturbations, time-lapse imaging of growth, and computational modeling, we find that ChCUC1 provides instructive input into auxin-based leaf margin patterning. This input arises via transcriptional regulation of multiple auxin homeostasis components, including direct activation of WAG kinases that are known to regulate the polarity of PIN-FORMED auxin transporters. Thus, we have uncovered a mechanism that bridges biological scales by linking spatially distributed and species-specific transcription factor expression to cell-level polarity and growth, to shape diverse leaf forms.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Polaridad Celular , Regulación de la Expresión Génica de las Plantas , Ácidos Indolacéticos , Hojas de la Planta , Ácidos Indolacéticos/metabolismo , Hojas de la Planta/crecimiento & desarrollo , Hojas de la Planta/genética , Hojas de la Planta/metabolismo , Polaridad Celular/genética , Arabidopsis/genética , Arabidopsis/crecimiento & desarrollo , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Cardamine/genética , Cardamine/metabolismo , Cardamine/crecimiento & desarrollo , Factores de Transcripción/metabolismo , Factores de Transcripción/genéticaRESUMEN
Leaf yellowing is a well-known phenotype that attracts phloem-feeding insects. However, it remains unclear how insect-vectored plant pathogens induce host leaf yellowing to facilitate their own transmission by insect vectors. Here, we report that an effector protein secreted by rice orange leaf phytoplasma (ROLP) inhibits chlorophyll biosynthesis and induces leaf yellowing to attract leafhopper vectors, thereby presumably promoting pathogen transmission. This effector, designated secreted ROLP protein 1 (SRP1), first secreted into rice phloem by ROLP, was subsequently translocated to chloroplasts by interacting with the chloroplastic glutamine synthetase (GS2). The direct interaction between SRP1 and GS2 disrupts the decamer formation of the GS2 holoenzyme, attenuating its enzymatic activity, thereby suppressing the synthesis of chlorophyll precursors glutamate and glutamine. Transgenic expression of SRP1 in rice plants decreased GS2 activity and chlorophyll precursor accumulation, finally inducing leaf yellowing. This process is correlated with the previous evidence that the knockout of GS2 expression in rice plants causes a similar yellow chlorosis phenotype. Consistently, these yellowing leaves attracted higher numbers of leafhopper vectors, caused the vectors to probe more frequently, and presumably facilitate more efficient phytoplasma transmission. Together, these results uncover the mechanism used by phytoplasmas to manipulate the leaf color of infected plants for the purpose of enhancing attractiveness to insect vectors.
Asunto(s)
Cloroplastos , Glutamato-Amoníaco Ligasa , Hemípteros , Insectos Vectores , Oryza , Phytoplasma , Hojas de la Planta , Animales , Hemípteros/microbiología , Glutamato-Amoníaco Ligasa/metabolismo , Glutamato-Amoníaco Ligasa/genética , Phytoplasma/fisiología , Hojas de la Planta/microbiología , Hojas de la Planta/metabolismo , Oryza/microbiología , Oryza/genética , Insectos Vectores/microbiología , Cloroplastos/metabolismo , Enfermedades de las Plantas/microbiología , Clorofila/metabolismo , Plantas Modificadas Genéticamente , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/genéticaRESUMEN
Endoplasmic reticulum (ER)-associated degradation (ERAD) plays key roles in controlling protein levels and quality in eukaryotes. The Ring Finger Protein 185 (RNF185)/membralin ubiquitin ligase complex was recently identified as a branch in mammals and is essential for neuronal function, but its function in plant development is unknown. Here, we report the map-based cloning and characterization of Narrow Leaf and Dwarfism 1 (NLD1), which encodes the ER membrane-localized protein membralin and specifically interacts with maize homologs of RNF185 and related components. The nld1 mutant shows defective leaf and root development due to reduced cell number. The defects of nld1 were largely restored by expressing membralin genes from Arabidopsis thaliana and mice, highlighting the conserved roles of membralin proteins in animals and plants. The excessive accumulation of ß-hydroxy ß-methylglutaryl-CoA reductase in nld1 indicates that the enzyme is a membralin-mediated ERAD target. The activation of bZIP60 mRNA splicing-related unfolded protein response signaling and marker gene expression in nld1, as well as DNA fragment and cell viability assays, indicate that membralin deficiency induces ER stress and cell death in maize, thereby affecting organogenesis. Our findings uncover the conserved, indispensable role of the membralin-mediated branch of the ERAD pathway in plants. In addition, ZmNLD1 contributes to plant architecture in a dose-dependent manner, which can serve as a potential target for genetic engineering to shape ideal plant architecture, thereby enhancing high-density maize yields.