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1.
New Phytol ; 2024 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-38725409

RESUMO

In angiosperms, wound-derived signals travel through the vasculature to systemically activate defence responses throughout the plant. In Arabidopsis thaliana, activity of vasculature-specific Clade 3 glutamate receptor-like (GLR) channels is required for the transmission of electrical signals and cytosolic Ca2+ ([Ca2+]cyt) waves from wounded leaves to distal tissues, triggering activation of oxylipin-dependent defences. Whether nonvascular plants mount systemic responses upon wounding remains unknown. To explore the evolution of systemic defence responses, we investigated electrical and calcium signalling in the nonvascular plant Marchantia polymorpha. We found that electrical signals and [Ca2+]cyt waves are generated in response to mechanical wounding and propagated to nondamaged distal tissues in M. polymorpha. Functional analysis of MpGLR, the only GLR encoded in the genome of M. polymorpha, indicates that its activity is necessary for the systemic transmission of wound-induced electrical signals and [Ca2+]cyt waves, similar to vascular plants. However, spread of these signals is neither coupled to systemic accumulation of oxylipins nor to a transcriptional defence response in the distal tissues of wounded M. polymorpha plants. Our results suggest that lack of vasculature prevents translocation of additional signalling factors that, together with electrical signals and [Ca2+]cyt waves, contribute to systemic activation of defences in tracheophytes.

3.
Plant Physiol Biochem ; 210: 108573, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38569423

RESUMO

Riboflavins are secreted under iron deficiency as a part of the iron acquisition Strategy I, mainly when the external pH is acidic. In plants growing under Fe-deficiency and alkaline conditions, riboflavins have been reported to accumulate inside the roots, with very low or negligible secretion. However, the fact that riboflavins may undergo hydrolysis under alkaline conditions has been so far disregarded. In this paper, we report the presence of riboflavin derivatives and products of their alkaline hydrolysis (lumichrome, lumiflavin and carboxymethylflavin) in nutrient solutions of Cucumis sativus plants grown under different iron regimes (soluble Fe-EDDHA in the nutrient solution, total absence of iron in the nutrient solution, or two different doses of FeSO4 supplied as a foliar spray), either cultivated in slightly acidic (pH 6) or alkaline (pH 8.8, 10 mM bicarbonate) nutrient solutions. The results show that root synthesis and exudation of riboflavins is controlled by shoot iron status, and that exuded riboflavins undergo hydrolysis, especially at alkaline pH, with lumichrome being the main product of hydrolysis.


Assuntos
Raízes de Plantas , Raízes de Plantas/metabolismo , Raízes de Plantas/efeitos dos fármacos , Hidrólise , Cucumis sativus/metabolismo , Cucumis sativus/efeitos dos fármacos , Deficiências de Ferro , Riboflavina/metabolismo , Concentração de Íons de Hidrogênio , Estresse Fisiológico/efeitos dos fármacos , Ferro/metabolismo , Exsudatos de Plantas/metabolismo
4.
Plant Cell Environ ; 2024 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-38500380

RESUMO

Chloroplast function is essential for growth, development, and plant adaptation to stress. Organelle stress and plant defence responses were examined here using noxy8 (nonresponding to oxylipins 8) from a series of Arabidopsis mutants. The noxy8 mutation was located at the CLPC2 gene, encoding a chloroplast chaperone of the protease complex CLP. Although its CLPC1 paralogue is considered to generate redundancy, our data reveal significant differences distinguishing CLPC2 and CLPC1 functions. As such, clpc1 mutants displayed a major defect in housekeeping chloroplast proteostasis, leading to a pronounced reduction in growth and pigment levels, enhanced accumulation of chloroplast and cytosol chaperones, and resistance to fosmidomycin. Conversely, clpc2 mutants showed severe susceptibility to lincomycin inhibition of chloroplast translation and resistance to Antimycin A inhibition of mitochondrial respiration. In the response to Pseudomonas syringae pv. tomato, clpc2 but not clpc1 mutants were resistant to bacterial infection, showing higher salicylic acid levels, defence gene expression and 9-LOX pathway activation. Our findings suggest CLPC2 and CLPC1 functional specificity, with a preferential involvement of CLPC1 in housekeeping processes and of CLPC2 in stress responses.

5.
J Exp Bot ; 2024 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-38465958

RESUMO

Modern crops exhibit diverse sensitivities to ammonium as the primary nitrogen source, influenced by environmental factors such as external pH and nutrient availability. Despite its significance, there is currently no systematic classification of plant species based on their ammonium sensitivity. This study conducts a meta-analysis of 50 plant species and presents a new classification method based on the comparison of fresh biomass obtained under ammonium and nitrate nutrition. The classification uses the natural logarithm of biomass ratio as the size effect indicator of ammonium sensitivity. This numerical parameter is associated with critical factors for nitrogen demand and form preference, such as Ellenberg indicators and the repertoire of nitrogen transporters for ammonium and nitrate uptake. Finally, a comparative analysis of the developmental and metabolic responses, including hormonal balance, is conducted in two species with divergent ammonium sensitivity values in the classification. Results indicate that nitrate has a key counteracting role of ammonium toxicity in species with a higher abundance of genes encoding NRT2-type proteins and fewer of the AMT2-type proteins. Additionally, the study confirms the reliability of the phytohormone balance and methylglyoxal content as indicators for anticipating ammonium toxicity.

6.
Funct Plant Biol ; 512024 02.
Artigo em Inglês | MEDLINE | ID: mdl-38388529

RESUMO

While the effect of CO2 enrichment on wheat (Triticum spp.) photosynthesis, nitrogen content or yield has been well-studied, the impact of elevated CO2 on metabolic pathways in organs other than leaves is poorly documented. In particular, glumes and awns, which may refix CO2 respired by developing grains and be naturally exposed to higher-than-ambient CO2 mole fraction, could show specific responses to elevated CO2 . Here, we took advantage of a free-air CO2 enrichment experiment and performed multilevel analyses, including metabolomics, ionomics, proteomics, major hormones and isotopes in Triticum durum . While in leaves, elevated CO2 tended to accelerate amino acid metabolism with many significantly affected metabolites, the effect on glumes and awns metabolites was modest. There was a lower content in compounds of the polyamine pathway (along with uracile and allantoin) under elevated CO2 , suggesting a change in secondary N metabolism. Also, cytokinin metabolism appeared to be significantly affected under elevated CO2 . Despite this, elevated CO2 did not affect the final composition of awn and glume organic matter, with the same content in carbon, nitrogen and other elements. We conclude that elevated CO2 mostly impacts on leaf metabolism but has little effect in awns and glumes, including their composition at maturity.


Assuntos
Dióxido de Carbono , Triticum , Triticum/metabolismo , Dióxido de Carbono/metabolismo , Fotossíntese , Folhas de Planta , Nitrogênio/metabolismo , Nitrogênio/farmacologia
8.
Front Plant Sci ; 14: 1180688, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37206971

RESUMO

Many studies have shown the capacity of soil humic substances (HS) to improve plant growth in natural ecosystems. This effect involves the activation of different processes within the plant at different coordinated molecular, biochemical, and physiological levels. However, the first event triggered by plant root-HS interaction remains unclear. Some studies suggest the hypothesis that the interaction of HS with root exudates involves relevant modification of the molecular conformation of humic self-assembled aggregates, including disaggregation, which might be directly involved in the activation of root responses. To investigate this hypothesis, we have prepared two humic acids. A natural humic acid (HA) and a transformed humic acid obtained from the treatment of HA with fungal laccase (HA enz). We have tested the capacity of the two humic acids to affect plant growth (cucumber and Arabidopsis) and complex Cu. Laccase-treatment did not change the molecular size but increased hydrophobicity, molecular compactness and stability, and rigidity of HA enz. Laccase-treatment avoided the ability of HA to promote shoot- and root-growth in cucumber and Arabidopsis. However, it does not modify Cu complexation features. There is no molecular disaggregation upon the interaction of HA and HA enz with plant roots. The results indicate that the interaction with plant roots induced in both HA and laccase-treated HA (HA enz), changes in their structural features that showed higher compactness and rigidity. These events might result from the interaction of HA and HA enz with specific root exudates that can promote intermolecular crosslinking. In summary, the results indicate that the weakly bond stabilized aggregated conformation (supramolecular-like) of HA plays a crucial role in its ability to promote root and shoot growth. The results also indicate the presence of two main types of HS in the rhizosphere corresponding to those non-interacting with plant roots (forming aggregated molecular assemblies) and those produced after interacting with plant root exudates (forming stable macromolecules).

9.
New Phytol ; 238(5): 2236-2246, 2023 06.
Artigo em Inglês | MEDLINE | ID: mdl-36942932

RESUMO

Different plant species employ different jasmonates to activate a conserved signalling pathway in land plants, where (+)-7-iso-JA-Ile (JA-Ile) is the ligand for the COI1/JAZ receptor in angiosperms and dn-cis-OPDA, dn-iso-OPDA and Δ4 -dn-iso-OPDA act as ligands in Marchantia polymorpha. In addition, some jasmonates play a COI1-independent role. To understand the distribution of bioactive jasmonates in the green lineage and how their biosynthetic pathways evolved, we performed phylogenetic analyses and systematic jasmonates profiling in representative species from different lineages. We found that both OPDA and dn-OPDA are ubiquitous in all tested land plants and present also in charophyte algae, underscoring their importance as ancestral signalling molecules. By contrast, JA-Ile biosynthesis emerged within lycophytes coincident with the evolutionary appearance of JAR1 function. We identified that the OPR3-independent JA biosynthesis pathway is ancient and predates the evolutionary appearance of the OPR3-dependent pathway. Moreover, we identified a negative correlation between dn-iso-OPDA and JA-Ile in land plants, which supports that in bryophytes and lycophytes dn-iso-OPDA represents the analogous hormone to JA-Ile in other vascular plants.


Assuntos
Vias Biossintéticas , Oxilipinas , Ligantes , Filogenia , Oxilipinas/metabolismo , Ciclopentanos/metabolismo , Isoleucina/metabolismo , Plantas/metabolismo
10.
Proc Natl Acad Sci U S A ; 119(49): e2212155119, 2022 12 06.
Artigo em Inglês | MEDLINE | ID: mdl-36442090

RESUMO

Jasmonates are phytohormones that regulate defense and developmental processes in land plants. Despite the chemical diversity of jasmonate ligands in different plant lineages, they are all perceived by COI1/JAZ co-receptor complexes, in which the hormone acts as a molecular glue between the COI1 F-box and a JAZ repressor. It has been shown that COI1 determines ligand specificity based on the receptor crystal structure and the identification of a single COI1 residue, which is responsible for the evolutionary switch in ligand binding. In this work, we show that JAZ proteins contribute to ligand specificity together with COI1. We propose that specific features of JAZ proteins, which are conserved in bryophytes and lycophytes, enable perception of dn-OPDA ligands regardless the size of the COI1 binding pocket. In vascular plant lineages beyond lycophytes, JAZ evolved to limit binding to JA-Ile, thus impeding dn-OPDA recognition by COI1.


Assuntos
Oxilipinas , Reguladores de Crescimento de Plantas , Ligantes
12.
Proc Natl Acad Sci U S A ; 119(36): e2202930119, 2022 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-36037336

RESUMO

In plants, jasmonate signaling regulates a wide range of processes from growth and development to defense responses and thermotolerance. Jasmonates, such as jasmonic acid (JA), (+)-7-iso-jasmonoyl-l-isoleucine (JA-Ile), 12-oxo-10,15(Z)-phytodienoic acid (OPDA), and dinor-12-oxo-10,15(Z)-phytodienoic acid (dn-OPDA), are derived from C18 (18 Carbon atoms) and C16 polyunsaturated fatty acids (PUFAs), which are found ubiquitously in the plant kingdom. Bryophytes are also rich in C20 and C22 long-chain polyunsaturated fatty acids (LCPUFAs), which are found only at low levels in some vascular plants but are abundant in organisms of other kingdoms, including animals. The existence of bioactive jasmonates derived from LCPUFAs is currently unknown. Here, we describe the identification of an OPDA-like molecule derived from a C20 fatty acid (FA) in the liverwort Marchantia polymorpha (Mp), which we term (5Z,8Z)-10-(4-oxo-5-((Z)-pent-2-en-1-yl)cyclopent-2-en-1-yl)deca-5,8-dienoic acid (C20-OPDA). This molecule accumulates upon wounding and, when applied exogenously, can activate known Coronatine Insensitive 1 (COI1) -dependent and -independent jasmonate responses. Furthermore, we identify a dn-OPDA-like molecule (Δ4-dn-OPDA) deriving from C20-OPDA and demonstrate it to be a ligand of the jasmonate coreceptor (MpCOI1-Mp Jasmonate-Zinc finger inflorescence meristem domain [MpJAZ]) in Marchantia. By analyzing mutants impaired in the production of LCPUFAs, we elucidate the major biosynthetic pathway of C20-OPDA and Δ4-dn-OPDA. Moreover, using a double mutant compromised in the production of both Δ4-dn-OPDA and dn-OPDA, we demonstrate the additive nature of these molecules in the activation of jasmonate responses. Taken together, our data identify a ligand of MpCOI1 and demonstrate LCPUFAs as a source of bioactive jasmonates that are essential to the immune response of M. polymorpha.


Assuntos
Marchantia , Oxilipinas , Ciclopentanos/metabolismo , Ácidos Graxos Insaturados/metabolismo , Ligantes , Marchantia/química , Marchantia/genética , Mutação , Oxilipinas/metabolismo
13.
Front Plant Sci ; 13: 803013, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35185979

RESUMO

Many studies have shown the close relationship between the beneficial action of soil and sedimentary humic acids on the growth of plants cultivated in calcareous soils and their ability to improve Fe plant nutrition. These results have been ascribed to the humic acid (HA) capability to improve Fe solubility and bioavailability. However, other effects more related to a humic acid action on the specific mechanisms activated in roots of plants under Fe deficiency cannot be ruled out. Although this question has been studied in dicotyledonous plants, in graminaceous plants there are no specific studies. Here we investigate the ability of a humic acid extracted from peat (HA) to improve Fe nutrition in wheat plants cultivated under Fe deficient and sufficient conditions. The results show that HA can improve the physiological status of Fe deficient wheat plants by alleviating some of the deleterious consequences of Fe deficiency on plant development and increasing the plant ability to secrete phytosiderophores to the nutrient solution. This action of HA is associated with increases in the Fe-active pool in leaves that might be related to the mobilization of the Fe complexed by HA resulting from the interaction of HA with the phytosiderophores in the nutrient solution. The Fe translocation from the root to the shoot may be favored by the action of trans-Zeatin Riboside (tZR) since the leaf concentration of this phytohormone was enhanced by HA in Fe deficient plants.

15.
New Phytol ; 233(3): 1401-1413, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-34846752

RESUMO

Jasmonates are fatty acid-derived hormones that regulate multiple aspects of plant development, growth and stress responses. Bioactive jasmonates, defined as the ligands of the conserved COI1 receptor, differ between vascular plants and bryophytes (jasmonoyl-l-isoleucine (JA-Ile) and dinor-12-oxo-10,15(Z)-phytodienoic acid (dn-OPDA), respectively). The biosynthetic pathways of JA-Ile in the model vascular plant Arabidopsis thaliana have been elucidated. However, the details of dn-OPDA biosynthesis in bryophytes are still unclear. Here, we identify an orthologue of Arabidopsis fatty-acid-desaturase 5 (AtFAD5) in the model liverwort Marchantia polymorpha and show that FAD5 function is ancient and conserved between species separated by more than 450 million years (Myr) of independent evolution. Similar to AtFAD5, MpFAD5 is required for the synthesis of 7Z-hexadecenoic acid. Consequently, in Mpfad5 mutants, the hexadecanoid pathway is blocked, dn-OPDA concentrations are almost completely depleted and normal chloroplast development is impaired. Our results demonstrate that the main source of wounding-induced dn-OPDA in Marchantia is the hexadecanoid pathway and the contribution of the octadecanoid pathway (i.e. from OPDA) is minimal. Remarkably, despite extremely low concentrations of dn-OPDA, MpCOI1-mediated responses to wounding and insect feeding can still be activated in Mpfad5, suggesting that dn-OPDA may not be the only bioactive jasmonate and COI1 ligand in Marchantia.


Assuntos
Arabidopsis , Marchantia , Arabidopsis/genética , Arabidopsis/metabolismo , Ciclopentanos/metabolismo , Ciclopentanos/farmacologia , Ácidos Graxos Dessaturases/genética , Ácidos Graxos Dessaturases/metabolismo , Marchantia/metabolismo , Oxilipinas/metabolismo , Oxilipinas/farmacologia
17.
Mol Plant ; 14(9): 1489-1507, 2021 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-34048950

RESUMO

In nature, plants acquire nutrients from soils to sustain growth, and at the same time, they need to avoid the uptake of toxic compounds and/or possess tolerance systems to cope with them. This is particularly challenging when the toxic compound and the nutrient are chemically similar, as in the case of phosphate and arsenate. In this study, we demonstrated that regulatory elements of the phosphate starvation response (PSR) coordinate the arsenate detoxification machinery in the cell. We showed that arsenate repression of the phosphate transporter PHT1;1 is associated with the degradation of the PSR master regulator PHR1. Once arsenic is sequestered into the vacuole, PHR1 stability is restored and PHT1;1 expression is recovered. Furthermore, we identified an arsenite responsive SKP1-like protein and a PHR1 interactor F-box (PHIF1) as constituents of the SCF complex responsible for PHR1 degradation.We found that arsenite, the form to which arsenate is reduced for compartmentalization in vacuoles, represses PHT1;1 expression, providing a highly selective signal versus phosphate to control PHT1;1 expression in response to arsenate. Collectively, our results provide molecular insights into a sensing mechanism that regulates arsenate/phosphate uptake depending on the plant's detoxification capacity.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arseniatos/metabolismo , Fatores de Transcrição/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Arseniatos/farmacologia , Transporte Biológico , Regulação da Expressão Gênica de Plantas , Proteínas de Transporte de Fosfato/genética , Proteínas de Transporte de Fosfato/metabolismo , Fosfatos/metabolismo , Plantas Geneticamente Modificadas , Fatores de Transcrição/genética , Vacúolos/metabolismo
18.
Molecules ; 26(1)2020 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-33374946

RESUMO

Some studies have reported that the capacity of humic substances to improve plant growth is dependent on their ability to increase root hydraulic conductivity. It was proposed that this effect is directly related to the structural conformation in solution of these substances. To study this hypothesis, the effects on root hydraulic conductivity and growth of cucumber plants of a sedimentary humic acid and two polymers-polyacrylic acid and polyethylene glycol-presenting a molecular conformation in water solution different from that of the humic acid have been studied. The results show that whereas the humic acid caused an increase in root hydraulic conductivity and plant growth, both the polyacrylic acid and the polyethylene glycol did not modify plant growth and caused a decrease in root hydraulic conductivity. These results can be explained by the different molecular conformation in water solution of the three molecular systems. The relationships between these biological effects and the molecular conformation of the three molecular systems in water solution are discussed.


Assuntos
Ácidos/química , Substâncias Húmicas/análise , Conformação Molecular , Fenilpropionatos/química , Desenvolvimento Vegetal , Raízes de Plantas/química , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Soluções
19.
Front Plant Sci ; 11: 837, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32636861

RESUMO

The global decrease in soil fertility leads to a new agricultural scenario where eco-friendly solutions play an important role. The plant growth promotion through the use of microbes, especially endophytes and rhizosphere microbiota, has been proposed as a useful solution. Several studies have shown that humic substances are suitable vehicles for the inoculation of plant growth promoting bacteria, and that this combination has an enhanced effect on the stimulation of plant development. In this work, cucumber plants grown hydroponically have been pre-treated with a sedimentary humic acid (SHA) with known plant growth-enhancing effects, and culturable bacterial endophytes have been isolated from these plants. The hypothesis was that this pre-treatment with SHA could lead to the isolation of certain endophytic taxa whose proliferation within the plant could have been promoted as a result of the effects of the treatment with SHA, and that could eventually reinforce a potential synergistic effect of a combined application of those endophytic bacteria and SHA. The culturable endophytes that have been isolated from humic acid-treated cucumber plants have been identified as members of four main phyla: Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes. Isolates were characterized according to the following plant growth-promoting traits: nitrogen fixation/scavenging, phosphate solubilization, siderophore production and plant hormone production. Most of the isolates were able to fix/scavenge nitrogen and to produce plant hormones (indole-3-acetic acid and several cytokinins), whereas few isolates were able to solubilize phosphate and/or produce siderophores. The most promising endophyte isolates for its use in futures investigations as plant growth-promoting bacterial inocula were Pseudomonas sp. strains (that showed all traits), Sphingomonas sp., Stenotrophomonas sp. strains, or some Arthrobacter sp. and Microbacterium sp. isolates.

20.
J Exp Bot ; 71(19): 5990-6003, 2020 10 07.
Artigo em Inglês | MEDLINE | ID: mdl-32687190

RESUMO

While the general effect of CO2 enrichment on photosynthesis, stomatal conductance, N content, and yield has been documented, there is still some uncertainty as to whether there are interactive effects between CO2 enrichment and other factors, such as temperature, geographical location, water availability, and cultivar. In addition, the metabolic coordination between leaves and grains, which is crucial for crop responsiveness to elevated CO2, has never been examined closely. Here, we address these two aspects by multi-level analyses of data from several free-air CO2 enrichment experiments conducted in five different countries. There was little effect of elevated CO2 on yield (except in the USA), likely due to photosynthetic capacity acclimation, as reflected by protein profiles. In addition, there was a significant decrease in leaf amino acids (threonine) and macroelements (e.g. K) at elevated CO2, while other elements, such as Mg or S, increased. Despite the non-significant effect of CO2 enrichment on yield, grains appeared to be significantly depleted in N (as expected), but also in threonine, the S-containing amino acid methionine, and Mg. Overall, our results suggest a strong detrimental effect of CO2 enrichment on nutrient availability and remobilization from leaves to grains.


Assuntos
Dióxido de Carbono , Triticum , Grão Comestível , Fotossíntese , Folhas de Planta
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