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1.
BMC Plant Biol ; 21(1): 334, 2021 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-34261431

RESUMO

BACKGROUND: The skin (exocarp) of fleshy fruit is hugely diverse across species. Most fruit types have a live epidermal skin covered by a layer of cuticle made up of cutin while a few create an outermost layer of dead cells (peridermal layer). RESULTS: In this study we undertook crosses between epidermal and peridermal skinned kiwifruit, and showed that epidermal skin is a semi-dominant trait. Furthermore, backcrossing these epidermal skinned hybrids to a peridermal skinned fruit created a diverse range of phenotypes ranging from epidermal skinned fruit, through fruit with varying degrees of patches of periderm (russeting), to fruit with a complete periderm. Quantitative trait locus (QTL) analysis of this population suggested that periderm formation was associated with four loci. These QTLs were aligned either to ones associated with russet formation on chromosome 19 and 24, or cuticle integrity and coverage located on chromosomes 3, 11 and 24. CONCLUSION: From the segregation of skin type and QTL analysis, it appears that skin development in kiwifruit is controlled by two competing factors, cuticle strength and propensity to russet. A strong cuticle will inhibit russeting while a strong propensity to russet can create a continuous dead skinned periderm.


Assuntos
Actinidia/genética , Frutas/genética , Genes de Plantas , Loci Gênicos , Desenvolvimento Vegetal/genética , Actinidia/crescimento & desenvolvimento , Cruzamentos Genéticos , Frutas/crescimento & desenvolvimento , Genótipo , Fenótipo , Locos de Características Quantitativas
2.
Int J Mol Sci ; 22(13)2021 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-34201662

RESUMO

Gene expression and phytohormone contents were measured in response to elevating ascorbate in the absence of other confounding stimuli such as high light and abiotic stresses. Young Arabidopsis plants were treated with 25 mM solutions of l-galactose pathway intermediates l-galactose (l-gal) or l-galactono-1,4-lactone (l-galL), as well as L-ascorbic acid (AsA), with 25 mM glucose used as control. Feeding increased rosette AsA 2- to 4-fold but there was little change in AsA biosynthetic gene transcripts. Of the ascorbate recycling genes, only Dehydroascorbate reductase 1 expression was increased. Some known regulatory genes displayed increased expression and included ANAC019, ANAC072, ATHB12, ZAT10 and ZAT12. Investigation of the ANAC019/ANAC072/ATHB12 gene regulatory network revealed a high proportion of ABA regulated genes. Measurement of a subset of jasmonate, ABA, auxin (IAA) and salicylic acid compounds revealed consistent increases in ABA (up to 4.2-fold) and phaseic acid (PA; up to 5-fold), and less consistently certain jasmonates, IAA, but no change in salicylic acid levels. Increased ABA is likely due to increased transcripts for the ABA biosynthetic gene NCED3. There were also smaller increases in transcripts for transcription factors ATHB7, ERD1, and ABF3. These results provide insights into how increasing AsA content can mediate increased abiotic stress tolerance.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/fisiologia , Ácido Ascórbico/metabolismo , Glutationa Transferase/genética , Reguladores de Crescimento de Plantas/metabolismo , Estresse Fisiológico/fisiologia , Ácido Abscísico/metabolismo , Arabidopsis/efeitos dos fármacos , Proteínas de Arabidopsis/metabolismo , Ascorbato Oxidase/genética , Ascorbato Oxidase/metabolismo , Ácido Ascórbico/genética , Ciclopentanos/metabolismo , Galactose/farmacologia , Regulação da Expressão Gênica de Plantas , Redes Reguladoras de Genes , Glutationa Transferase/metabolismo , Ácidos Hexurônicos/metabolismo , Ácidos Indolacéticos/metabolismo , Oxilipinas/metabolismo , Reguladores de Crescimento de Plantas/genética , Sesquiterpenos/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
3.
Funct Plant Biol ; 47(12): 1019-1031, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32571472

RESUMO

The outer skin layer in any plant is essential in offering a protective barrier against water loss and pathogen attack. Within fleshy fruit, the skin supports internal cell layers and can provide the initial cues in attracting seed-dispersing animals. The skin of a fruit, termed the exocarp, is a key element of consumer preference and a target for many breeding programs. Across fruiting species there is a huge diversity of exocarp types and these range from a simple single living cell layer (epidermis) often covered with a waxy layer, to complex multicellular suberised and dead cell layers (periderm), with various intermediate russet forms in between. Each exocarp can be interspersed with other structures such as hairs or spines. The epidermis has been well characterised and remains pluripotent with the help of the cells immediately under the epidermis. The periderm, in contrast, is the result of secondary meristematic activity, which replaces the epidermal layers, and is not well characterised in fruits. In this review we explore the structure, composition and mechanisms that control the development of a periderm type fruit exocarp. We draw upon literature from non-fleshy fruit species that form periderm tissue, from which a considerable amount of research has been undertaken.


Assuntos
Frutas , Meristema , Animais , Células Epidérmicas , Epiderme , Água
4.
Curr Opin Biotechnol ; 44: 153-160, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-28231513

RESUMO

Ascorbate (or vitamin C) is an essential human micronutrient predominantly obtained from plants. In addition to preventing scurvy, it is now known to have broader roles in human health, for example as a cofactor for enzymes involved in epigenetic programming and as regulator of cellular iron uptake. Furthermore, ascorbate is the major antioxidant in plants and underpins many environmentally induced abiotic stress responses. Biotechnological approaches to enhance the ascorbate content of crops therefore have potential to improve both human health and abiotic stress tolerance of crops. Identifying the genetic basis of ascorbate variation between plant varieties and discovering how some 'super fruits' accumulate extremely high levels of ascorbate should reveal new ways to more effectively manipulate the production of ascorbate in crops.


Assuntos
Antioxidantes/farmacologia , Ácido Ascórbico/farmacologia , Produtos Agrícolas/efeitos dos fármacos , Fenômenos Fisiológicos Vegetais/efeitos dos fármacos , Estresse Fisiológico/efeitos dos fármacos , Humanos
5.
Plant Cell ; 27(3): 772-86, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25724639

RESUMO

Ascorbate (vitamin C) is an essential antioxidant and enzyme cofactor in both plants and animals. Ascorbate concentration is tightly regulated in plants, partly to respond to stress. Here, we demonstrate that ascorbate concentrations are determined via the posttranscriptional repression of GDP-l-galactose phosphorylase (GGP), a major control enzyme in the ascorbate biosynthesis pathway. This regulation requires a cis-acting upstream open reading frame (uORF) that represses the translation of the downstream GGP open reading frame under high ascorbate concentration. Disruption of this uORF stops the ascorbate feedback regulation of translation and results in increased ascorbate concentrations in leaves. The uORF is predicted to initiate at a noncanonical codon (ACG rather than AUG) and encode a 60- to 65-residue peptide. Analysis of ribosome protection data from Arabidopsis thaliana showed colocation of high levels of ribosomes with both the uORF and the main coding sequence of GGP. Together, our data indicate that the noncanonical uORF is translated and encodes a peptide that functions in the ascorbate inhibition of translation. This posttranslational regulation of ascorbate is likely an ancient mechanism of control as the uORF is conserved in GGP genes from mosses to angiosperms.


Assuntos
Arabidopsis/genética , Ácido Ascórbico/biossíntese , Retroalimentação Fisiológica , Regulação da Expressão Gênica de Plantas , Fases de Leitura Aberta/genética , Regiões 5' não Traduzidas/genética , Sequência de Aminoácidos , Arabidopsis/efeitos dos fármacos , Ácido Ascórbico/farmacologia , Vias Biossintéticas/efeitos dos fármacos , Códon/genética , Regulação para Baixo/efeitos dos fármacos , Retroalimentação Fisiológica/efeitos dos fármacos , Galactose/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Luciferases/metabolismo , Dados de Sequência Molecular , Peptídeos/química , Fosfotransferases/metabolismo , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Regiões Promotoras Genéticas/genética , Biossíntese de Proteínas/efeitos dos fármacos , Ribossomos/efeitos dos fármacos , Ribossomos/metabolismo
6.
J Agric Food Chem ; 61(3): 728-39, 2013 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-23289429

RESUMO

In the last 30 years the incidence of kiwifruit allergy has increased with the three major allergenic proteins being identified as actinidin, kiwellin, and thaumatin-like protein (TLP). We report wide variation in the levels of actinidin and TLP in 15 kiwifruit varieties from the four most widely cultivated Actinidia species. Acidic and basic isoforms of actinidin were identified in Actinidia deliciosa 'Hayward' and Actinidia arguta 'Hortgem Tahi', while only a basic isoform of actinidin was identified in Actinidia chinensis 'Hort16A'. One isoform each of kiwellin and TLP were identified in ripe fruit. The cysteine protease activity of actinidin correlated with protein levels in all species except A. arguta. Protein modeling suggested that modifications to the S2 binding pocket influenced substrate specificity of the A. arguta enzyme. Our results indicate that care is necessary when extrapolating allergenicity results from single varieties to others within the same and between different Actinidia species.


Assuntos
Actinidia/química , Alérgenos/química , Antígenos de Plantas/química , Cisteína Endopeptidases/química , Frutas/química , Proteínas de Plantas/química , Actinidia/imunologia , Alérgenos/imunologia , Sequência de Aminoácidos , Antígenos de Plantas/imunologia , Western Blotting , Cromatografia Líquida , Cisteína Endopeptidases/imunologia , Eletroforese em Gel de Poliacrilamida , Espectrometria de Massas , Dados de Sequência Molecular , Proteínas de Plantas/imunologia , Conformação Proteica
7.
Physiol Plant ; 147(2): 121-34, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22568767

RESUMO

In pear and apple, depletion of ascorbate has previously been associated with development of stress-related flesh browning. This disorder occurs in intact fruit and differs from browning associated with tissue maceration and processing. We investigated changes in ascorbate content, ascorbate peroxidase (APX) activities and gene expression of l-galactose pathway genes, ascorbate recycling genes and APXs from harvest to 30 days storage for three pear varieties ['Williams Bon Chretien' (WBC), 'Doyenne du Comice' and 'Beurre Bosc']. The pears were stored at 0.5°C in air or controlled atmosphere (CA, 2 kPa O(2) and 5 kPa CO(2)). Storage in CA caused significant amounts of storage disorders in WBC only. Ascorbate content generally declined after harvest, although a transient increase in ascorbate in the form of dehydroascorbate (DHA) between harvest and 3 days was observed in CA stored WBC, possibly due to low at-harvest monodehydroascorbate reductase and CA-decreased dehydroascorbate reductase expression. Quantitative polymerase chain reaction indicated that all cultivars responded to CA storage by increasing transcripts for APXs, and surprisingly the pre-l-galactose pathway gene GDP-mannose pyrophosphorylase, of which the product GDP mannose, is utilized either for cell wall polysaccharides, protein N-glycosylation or ascorbate production. Overall, the small differences in ascorbate we observed suggest how ascorbate is utilized, rather than ascorbate content, determines the potential to develop internal browning. Moreover, a transitory increase in DHA postharvest may indicate that fruits are at risk of developing the disorder.


Assuntos
Ácido Ascórbico/metabolismo , Armazenamento de Alimentos , Frutas/metabolismo , Pyrus/metabolismo , Ar , Ascorbato Oxidase/genética , Ascorbato Oxidase/metabolismo , Ácido Ascórbico/análise , Temperatura Baixa , Frutas/enzimologia , Frutas/genética , Regulação da Expressão Gênica de Plantas , Oxirredutases/genética , Oxirredutases/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Pyrus/enzimologia , Pyrus/genética , Transcriptoma
8.
J Exp Bot ; 60(3): 765-78, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19129165

RESUMO

Vitamin C (L-ascorbic acid, AsA) is an essential metabolite for plants and animals. Kiwifruit (Actinidia spp.) are a rich dietary source of AsA for humans. To understand AsA biosynthesis in kiwifruit, AsA levels and the relative expression of genes putatively involved in AsA biosynthesis, regeneration, and transport were correlated by quantitative polymerase chain reaction in leaves and during fruit development in four kiwifruit genotypes (three species; A. eriantha, A. chinensis, and A. deliciosa). During fruit development, fruit AsA concentration peaked between 4 and 6 weeks after anthesis with A. eriantha having 3-16-fold higher AsA than other genotypes. The rise in AsA concentration typically occurred close to the peak in expression of the L-galactose pathway biosynthetic genes, particularly the GDP-L-galactose guanyltransferase gene. The high concentration of AsA found in the fruit of A. eriantha is probably due to higher expression of the GDP-mannose-3',5'-epimerase and GDP-L-galactose guanyltransferase genes. Over-expression of the kiwifruit GDP-L-galactose guanyltransferase gene in Arabidopsis resulted in up to a 4-fold increase in AsA, while up to a 7-fold increase in AsA was observed in transient expression studies where both GDP-L-galactose guanyltransferase and GDP-mannose-3',5'-epimerase genes were co-expressed. These studies show the importance of GDP-L-galactose guanyltransferase as a rate-limiting step to AsA, and demonstrate how AsA can be significantly increased in plants.


Assuntos
Actinidia/enzimologia , Actinidia/genética , Arabidopsis/metabolismo , Ácido Ascórbico/biossíntese , Frutas/genética , Regulação da Expressão Gênica de Plantas , Nucleotidiltransferases/genética , Arabidopsis/genética , Frutas/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Genes de Plantas , Genótipo , Inositol/metabolismo , Nucleotidiltransferases/metabolismo , Oxirredução , Folhas de Planta/genética , Folhas de Planta/metabolismo , Reação em Cadeia da Polimerase , Tabaco/metabolismo , Transformação Genética
9.
Mol Nutr Food Res ; 52 Suppl 2: S230-40, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-18925615

RESUMO

Allergy to kiwifruit appears to have become more common in Europe and elsewhere during the past several years. Seven allergens have been identified from kiwifruit so far, with actinidin, kiwellin and the thaumatin-like protein as the most relevant ones. In contrast to other fruits, no Bet v 1 homologues were characterized from kiwifruit so far. We cloned, purified, and characterized recombinant Bet v 1-homologous allergens from green (Actinidia deliciosa, Act d 8) and gold (Actinidia chinensis, Act c 8) kiwifruit, and confirmed the presence of its natural counterpart by inhibition assays. Well-characterized recombinant Act d 8 and Act c 8 were recognized by birch pollen/kiwifruit (confirmed by double-blind placebo-controlled food challenge) allergic patients in IgE immunoblots and ELISA experiments. The present data point out that Bet v 1 homologues are allergens in kiwifruit and of relevance for patients sensitized to tree pollen and kiwifruit, and might have been neglected so far due to low abundance in the conventional extracts used for diagnosis.


Assuntos
Actinidia/imunologia , Alérgenos/isolamento & purificação , Hipersensibilidade Alimentar/etiologia , Proteínas de Plantas/isolamento & purificação , Rinite Alérgica Sazonal/etiologia , Adulto , Alérgenos/química , Sequência de Aminoácidos , Antígenos de Plantas , Clonagem Molecular , Reações Cruzadas , Ensaio de Imunoadsorção Enzimática , Humanos , Immunoblotting , Imunoglobulina E/sangue , Pessoa de Meia-Idade , Dados de Sequência Molecular , Proteínas de Plantas/química , Reação em Cadeia da Polimerase , Proteínas Recombinantes/isolamento & purificação
10.
BMC Genomics ; 9: 351, 2008 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-18655731

RESUMO

BACKGROUND: Kiwifruit (Actinidia spp.) are a relatively new, but economically important crop grown in many different parts of the world. Commercial success is driven by the development of new cultivars with novel consumer traits including flavor, appearance, healthful components and convenience. To increase our understanding of the genetic diversity and gene-based control of these key traits in Actinidia, we have produced a collection of 132,577 expressed sequence tags (ESTs). RESULTS: The ESTs were derived mainly from four Actinidia species (A. chinensis, A. deliciosa, A. arguta and A. eriantha) and fell into 41,858 non redundant clusters (18,070 tentative consensus sequences and 23,788 EST singletons). Analysis of flavor and fragrance-related gene families (acyltransferases and carboxylesterases) and pathways (terpenoid biosynthesis) is presented in comparison with a chemical analysis of the compounds present in Actinidia including esters, acids, alcohols and terpenes. ESTs are identified for most genes in color pathways controlling chlorophyll degradation and carotenoid biosynthesis. In the health area, data are presented on the ESTs involved in ascorbic acid and quinic acid biosynthesis showing not only that genes for many of the steps in these pathways are represented in the database, but that genes encoding some critical steps are absent. In the convenience area, genes related to different stages of fruit softening are identified. CONCLUSION: This large EST resource will allow researchers to undertake the tremendous challenge of understanding the molecular basis of genetic diversity in the Actinidia genus as well as provide an EST resource for comparative fruit genomics. The various bioinformatics analyses we have undertaken demonstrates the extent of coverage of ESTs for genes encoding different biochemical pathways in Actinidia.


Assuntos
Actinidia/genética , Actinidia/fisiologia , Bases de Dados Genéticas , Etiquetas de Sequências Expressas , Frutas/crescimento & desenvolvimento , Pigmentação/genética , Paladar , Actinidia/crescimento & desenvolvimento , Actinidia/metabolismo , Adulto , Alérgenos/genética , Ácido Ascórbico/genética , Ácido Ascórbico/metabolismo , Criança , Códon , Sequência Consenso , Ésteres/metabolismo , Frutas/genética , Frutas/metabolismo , Genes de Plantas/genética , Marcadores Genéticos , Humanos , Repetições de Microssatélites , Dados de Sequência Molecular , Análise de Sequência com Séries de Oligonucleotídeos , Filogenia , Pigmentos Biológicos/biossíntese , Pigmentos Biológicos/genética , Polimorfismo de Nucleotídeo Único , Ácido Quínico/metabolismo , Análise de Sequência , Terpenos/metabolismo
11.
Proc Natl Acad Sci U S A ; 104(22): 9534-9, 2007 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-17485667

RESUMO

The gene for one postulated enzyme that converts GDP-L-galactose to L-galactose-1-phosphate is unknown in the L-galactose pathway of ascorbic acid biosynthesis and a possible candidate identified through map-based cloning is the uncharacterized gene At4g26850. We identified a putative function for At4g26850 using PSI-Blast and motif searching to show it was a member of the histidine triad superfamily, which includes D-galactose uridyltransferase. We cloned and expressed this Arabidopsis gene and the homologous gene from Actinidia chinensis in Escherichia coli and assayed the expressed protein for activities related to converting GDP-L-galactose to L-galactose-1-P. The expressed protein is best described as a GDP-L-galactose-hexose-1-phosphate guanyltransferase (EC 2.7.7.), catalyzing the transfer of GMP from GDP-l-galactose to a hexose-1-P, most likely D-mannose-1-phosphate in vivo. Transient expression of this A. chinensis gene in tobacco leaves resulted in a >3-fold increase in leaf ascorbate as well as a 50-fold increase in GDP-L-galactose-D-mannose-1-phosphate guanyltransferase activity.


Assuntos
Ácido Ascórbico/metabolismo , Galactose/metabolismo , Nucleotidiltransferases/metabolismo , Folhas de Planta/metabolismo , Actinidia/enzimologia , Actinidia/genética , Sequência de Aminoácidos , Animais , Arabidopsis/enzimologia , Arabidopsis/genética , Ácido Ascórbico/biossíntese , Espectrometria de Massas , Dados de Sequência Molecular , Nucleotidiltransferases/química , Nucleotidiltransferases/genética , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Especificidade por Substrato , Fosfatos Açúcares/metabolismo , Tabaco/genética , Tabaco/metabolismo
12.
Plant Biotechnol J ; 3(2): 215-23, 2005 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17173621

RESUMO

The availability of short stature apple scions that required minimal applications of chemical growth retardants and could be used with a range of rootstocks would be of considerable benefit to fruit growers. We have suppressed the expression of a gene encoding the gibberellin (GA) biosynthetic enzyme GA 20-oxidase to reduce the levels of bioactive GAs in a scion variety, resulting in significant reductions in stem height. Application of GA3 reversed the effect. The scion remained dwarfed after grafting on to normally invigorating rootstocks, whilst control plants of the same cultivar displayed the expected vigour when grafted on to these rootstocks. This approach could be applicable to any perennial crop variety, allowing dwarf trees to be obtained on any available rootstock or on their own roots without the need for chemical growth retardant application. In effect, seedlings that are well suited to local conditions (drought, salinity) could be employed as tree rootstocks, as could existing rootstocks valued for characters other than vigour control, such as pest and disease resistance.

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