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1.
Nat Biotechnol ; 2024 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-38267759

RESUMO

Clonal propagation of plants by induction of adventitious roots (ARs) from stem cuttings is a requisite step in breeding programs. A major barrier exists for propagating valuable plants that naturally have low capacity to form ARs. Due to the central role of auxin in organogenesis, indole-3-butyric acid is often used as part of commercial rooting mixtures, yet many recalcitrant plants do not form ARs in response to this treatment. Here we describe the synthesis and screening of a focused library of synthetic auxin conjugates in Eucalyptus grandis cuttings and identify 4-chlorophenoxyacetic acid-L-tryptophan-OMe as a competent enhancer of adventitious rooting in a number of recalcitrant woody plants, including apple and argan. Comprehensive metabolic and functional analyses reveal that this activity is engendered by prolonged auxin signaling due to initial fast uptake and slow release and clearance of the free auxin 4-chlorophenoxyacetic acid. This work highlights the utility of a slow-release strategy for bioactive compounds for more effective plant growth regulation.

2.
Development ; 150(21)2023 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-37882831

RESUMO

Plants have developed an array of mechanisms to protect themselves against pathogen invasion. The deployment of defense mechanisms is imperative for plant survival, but can come at the expense of plant growth, leading to the 'growth-defense trade-off' phenomenon. Following pathogen exposure, plants can develop resistance to further attack. This is known as induced resistance, or priming. Here, we investigated the growth-defense trade-off, examining how defense priming via systemic acquired resistance (SAR), or induced systemic resistance (ISR), affects tomato development and growth. We found that defense priming can promote, rather than inhibit, plant development, and that defense priming and growth trade-offs can be uncoupled. Cytokinin response was activated during induced resistance, and found to be required for the observed growth and disease resistance resulting from ISR activation. ISR was found to have a stronger effect than SAR on plant development. Our results suggest that growth promotion and induced resistance can be co-dependent, and that, in certain cases, defense priming can drive developmental processes and promote plant yield.


Assuntos
Solanum lycopersicum , Citocininas , Desenvolvimento Vegetal , Resistência Sistêmica Adquirida da Planta
3.
Front Plant Sci ; 13: 1066142, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36874915

RESUMO

The date palm (Phoenix dactylifera L.) fruit is of major importance for the nutrition of broad populations in the world's desert strip; yet it is sorely understudied. Understanding the mechanism regulating date fruit development and ripening is essential to customise date crop to the climatic change, which elaborates yield losses due to often too early occurring wet season. This study aimed to uncover the mechanism regulating date fruit ripening. To that end, we followed the natural process of date fruit development and the effects of exogenous hormone application on fruit ripening in the elite cultivar 'Medjool'. The results of the current study indicate that the onset of fruit ripening occurre once the seed had reached maximum dry weight. From this point, fruit pericarp endogenous abscisic acid (ABA) levels consistently increased until fruit harvest. The final stage in fruit ripening, the yellow-to-brown transition, was preceded by an arrest of xylem-mediated water transport into the fruit. Exogenous ABA application enhanced fruit ripening when applied just before the green-to-yellow fruit color transition. Repeated ABA applications hastened various fruit ripening processes, resulting in earlier fruit harvest. The data presented supports a pivotal role for ABA in the regulation of date fruit ripening.

4.
Planta ; 255(1): 18, 2021 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-34894276

RESUMO

MAIN CONCLUSION: Elevated temperatures suppress cell division in developing petunia buds leading to smaller flowers, mediated by ABA. Flower size is one of the most important showy traits in determining pollinator attraction, and a central factor determining the quality of floricultural products. Whereas the adverse effects of elevated temperatures on showy traits have been described in detail, its underlining mechanisms is poorly understood. Here, we investigated the physiological mechanism responsible for the reduction of flower size in petunia under elevated temperatures. We found that the early stages of flower-bud development were most sensitive to elevated temperatures, resulting in a drastic reduction of flower diameter that was almost independent of flower load. We demonstrated that the temperature-mediated flower size reduction occurred due to a shorter growth period, and a lower rate of corolla cell division. Consistently, local application of cytokinin, a phytohormone that promotes cell division, resulted in recovery of flower dimensions when grown under elevated temperatures. Hormone analysis of temperature-inhibited flower buds revealed no significant changes in levels of cytokinin, and a specific increase of abscisic acid (ABA) levels, known to inhibit cell division. Moreover, local application of ABA on flower buds caused a reduction of flower dimensions as a result of lower levels of cell division, suggesting that ABA mediates the reduction of flower size at elevated temperatures. Taken together, our results shed light on the mechanism by which elevated temperatures decrease petunia flower size, and show that temperature-mediated reduction of flower size can be alleviated by increasing the cytokinin/ABA ratio.


Assuntos
Petunia , Ácido Abscísico , Divisão Celular , Flores , Temperatura
5.
Front Plant Sci ; 12: 670772, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34512679

RESUMO

The role of the 9-lipoxygenase (9-LOX)-derived oxylipins in plant defense is mainly known in solanaceous plants. In this work, we identify the functional role of the tomato divinyl ether synthase (LeDES) branch, which exclusively converts 9-hydroperoxides to the 9-divinyl ethers (DVEs) colneleic acid (CA) and colnelenic acid (CnA), during infection by the root-knot nematode Meloidogyne javanica. Analysis of LeDES expression in roots indicated a concurrent response to nematode infection, demonstrating a sharp increase in expression during the molting of third/fourth-stage juveniles, 15 days after inoculation. Spatiotemporal expression analysis using an LeDES promoter:GUS tomato line showed high GUS activity associated with the developing gall; however the GUS signal became more constricted as infection progressed to the mature nematode feeding sites, and eventually disappeared. Wounding did not activate the LeDES promoter, but auxins and methyl salicylate triggered LeDES expression, indicating a hormone-mediated function of DVEs. Heterologous expression of LeDES in Arabidopsis thaliana rendered the plants more resistant to nematode infection and resulted in a significant reduction in third/fourth-stage juveniles and adult females as compared to a vector control and the wild type. To further evaluate the nematotoxic activity of the DVEs CA and CnA, recombinant yeast that catalyzes the formation of CA and CnA from 9-hydroperoxides was generated. Transgenic yeast accumulating CnA was tested for its impact on M. javanica juveniles, indicating a decrease in second-stage juvenile motility. Taken together, our results suggest an important role for LeDES as a determinant in the defense response during M. javanica parasitism, and indicate two functional modes: directly via DVE motility inhibition effect and through signal molecule-mediated defense reactions to nematodes that depend on methyl salicylate.

6.
J Struct Biol ; 213(3): 107777, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34391905

RESUMO

Glycosylation is one of the common modifications of plant metabolites, playing a major role in the chemical/biological diversity of a wide range of compounds. Plant metabolite glycosylation is catalyzed almost exclusively by glycosyltransferases, mainly by Uridine-diphosphate dependent Glycosyltransferases (UGTs). Several X-ray structures have been determined for primary glycosyltransferases, however, little is known regarding structure-function aspects of sugar-sugar/branch-forming O-linked UGTs (SBGTs) that catalyze the transfer of a sugar from the UDP-sugar donor to an acceptor sugar moiety of a previously glycosylated metabolite substrate. In this study we developed novel insights into the structural basis for SBGT catalytic activity by modelling the 3d-structures of two enzymes; a rhamnosyl-transferase Cs1,6RhaT - that catalyzes rhamnosylation of flavonoid-3-glucosides and flavonoid-7-glucosides and a UGT94D1 - that catalyzes glucosylation of (+)-Sesaminol 2-O-ß-d-glucoside at the C6 of the primary sugar moiety. Based on these structural models and docking studies a glutamate (E290 or E268 in Cs1,6RhaT or UGT94D1, respectively) and a tryptophan (W28 or W15 in Cs1,6RhaT or UGT94D1, respectively) appear to interact with the sugar acceptor and are suggested to be important for the recognition of the sugar-moiety of the acceptor-substrate. Functional analysis of substitution mutants for the glutamate and tryptophan residues in Cs1,6RhaT further support their role in determining sugar-sugar/branch-forming GT specificity. Phylogenetic analysis of the UGT family in plants demonstrates that the glutamic-acid residue is a hallmark of SBGTs that is entirely absent from the corresponding position in primary UGTs.


Assuntos
Glicosiltransferases , Difosfato de Uridina , Ácido Glutâmico , Glicosiltransferases/química , Glicosiltransferases/genética , Glicosiltransferases/metabolismo , Filogenia , Proteínas de Plantas/química , Especificidade por Substrato , Açúcares , Difosfato de Uridina/química
7.
Plant Physiol ; 185(4): 1708-1721, 2021 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-33793932

RESUMO

Shoot branching is an important aspect of plant architecture because it substantially affects plant biology and agricultural performance. Sugars play an important role in the induction of shoot branching in several species, including potato (Solanum tuberosum L.). However, the mechanism by which sugars affect shoot branching remains mostly unknown. In the present study, we addressed this question using sugar-mediated induction of bud outgrowth in potato stems under etiolated conditions. Our results indicate that sucrose feeding to detached stems promotes the accumulation of cytokinin (CK), as well as the expression of vacuolar invertase (VInv), an enzyme that contributes to sugar sink strength. These effects of sucrose were suppressed by CK synthesis and perception inhibitors, while CK supplied to detached stems induced bud outgrowth and VInv activity in the absence of sucrose. CK-induced bud outgrowth was suppressed in vinv mutants, which we generated by genome editing. Altogether, our results identify a branching-promoting module, and suggest that sugar-induced lateral bud outgrowth is in part promoted by the induction of CK-mediated VInv activity.


Assuntos
Citocininas/metabolismo , Reguladores de Crescimento de Plantas/metabolismo , Brotos de Planta/crescimento & desenvolvimento , Brotos de Planta/metabolismo , Solanum tuberosum/crescimento & desenvolvimento , Solanum tuberosum/metabolismo , Sacarose/metabolismo , Produtos Agrícolas/crescimento & desenvolvimento , Produtos Agrícolas/metabolismo , Variação Genética , Genótipo , Israel , Mutação , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Plantas Geneticamente Modificadas/metabolismo
8.
Hortic Res ; 8(1): 17, 2021 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-33423039

RESUMO

Mango fruit exposed to sunlight develops red skin and are more resistant to biotic and abiotic stresses. Here we show that harvested red mango fruit that was exposed to sunlight at the orchard is more resistant than green fruit to Colletotrichum gloeosporioides. LCMS analysis showed high amounts of antifungal compounds, as glycosylated flavonols, glycosylated anthocyanins, and mangiferin in red vs. green mango skin, correlated with higher antioxidant and lower ROS. However, also the green side of red mango fruit that has low levels of flavonoids was resistant, indicated induced resistance. Transcriptomes of red and green fruit inoculated on their red and green sides with C. gloeosporioides were analyzed. Overall, in red fruit skin, 2,187 genes were upregulated in response to C. gloeosporioides. On the green side of red mango, upregulation of 22 transcription factors and 33 signaling-related transcripts indicated induced resistance. The RNA-Seq analysis suggests that resistance of the whole red fruit involved upregulation of ethylene, brassinosteroid, and phenylpropanoid pathways. To conclude, red fruit resistance to fungal pathogen was related to both flavonoid toxicity and primed resistance of fruit that was exposed to light at the orchard.

9.
Plant J ; 73(1): 166-78, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22989156

RESUMO

Domestication and breeding of citrus species/varieties for flavor and other characteristics, based on the ancestral species pummelo, mandarin and citron, has been an ongoing process for thousands of years. Bitterness, a desirable flavor characteristic in the fruit of some citrus species (pummelo and grapefruit) and undesirable in others (oranges and mandarins), has been under positive or negative selection during the breeding process of new species/varieties. Bitterness in citrus fruit is determined by the composition of branched-chain flavanone glycosides, the predominant flavonoids in citrus. The flavor-determining biosynthetic step is catalyzed by two branch-forming rhamnosyltransferases that utilize flavanone-7-O-glucose as substrate. The 1,2-rhamnosytransferase (encoded by Cm1,2RhaT) leads to the bitter flavanone-7-O-neohesperidosides whereas the 1,6-rhamnosytransferase leads to the tastelessflavanone-7-O-rutinosides. Here, we describe the functional characterization of Cs1,6RhaT, a 1,6-rhamnosyltransferase-encoding gene directing biosynthesis of the tasteless flavanone rutinosides common to the non-bitter citrus species. Cs1,6RhaT was found to be a substrate-promiscuous enzyme catalyzing branched-chain rhamnosylation of flavonoids glucosylated at positions 3 or 7. In vivo substrates include flavanones, flavones, flavonols and anthocyanins. Cs1,6RhaT enzyme levels were shown to peak in young fruit and leaves, and gradually subside during development. Phylogenetic analysis of Cm1,2RhaT and Cs1,6RhaT demonstrated that they both belong to the branch-forming glycosyltransferase cluster, but are distantly related and probably originated separately before speciation of the citrus genome. Genomic data from citrus, supported by a study of Cs1,6RhaT protein levels in various citrus species, suggest that inheritance, expression levels and mutations of branch-forming rhamnosyltransferases underlie the development of bitter or non-bitter species/varieties under domestication.


Assuntos
Citrus sinensis/genética , Hexosiltransferases/metabolismo , Antocianinas/metabolismo , Citrus sinensis/enzimologia , Evolução Molecular , Flavanonas/metabolismo , Flavonóis/metabolismo , Frutas/enzimologia , Frutas/metabolismo , Genes de Plantas/genética , Genes de Plantas/fisiologia , Dados de Sequência Molecular , Filogenia , Melhoramento Vegetal , Folhas de Planta/enzimologia , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo
10.
Planta ; 234(1): 61-71, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21369922

RESUMO

Anthocyanins are the largest and best studied group of plant pigments. However, not very much is known about the fate of these phenolic pigments after they have accumulated in the cell vacuoles of plant tissues. We have previously shown that magnesium treatment of ornamentals during the synthesis of anthocyanins in the flowers or foliage caused an increase in the pigment concentration. In this study, we characterized the effect of magnesium on the accumulation of anthocyanin in red cell suspension originating from Vitis vinifera cv. Gamay Red grapes. Magnesium treatment of the cells caused a 2.5- to 4.5-fold increase in anthocyanin concentration, with no substantial induction of the biosynthetic genes. This treatment inhibited the degradation of anthocyanins occurring in the cells, and changed the ratio between different anthocyanins determining cell color, with an increase in the relative concentration of the less stable pigment molecules. The process by which magnesium treatment affects anthocyanin accumulation is still not clear. However, the results presented suggest at least part of its effect on anthocyanin accumulation stems from inhibition of the pigments' catabolism. When anthocyanin biosynthesis was inhibited, magnesium treatments prevented the constant degradation of anthocyanins in the cell suspension. Future understanding of the catabolic processes undergone by anthocyanins in plants may enable more efficient inhibition of this process and increased accumulation of these pigments, and possibly of additional phenolic compounds.


Assuntos
Antocianinas/metabolismo , Magnésio/farmacologia , Vitis/efeitos dos fármacos , Vitis/metabolismo , Antocianinas/biossíntese , Antocianinas/genética , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Vitis/citologia , Vitis/genética
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