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1.
Plant Sci ; 312: 111052, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34620447

RESUMO

Drought occurrence seriously affects the productivity and quality of apple crop worldwide. Autophagy, a conserved process for the degradation and recycling of unwanted cellular components, is considered to positively regulate the tolerance of various abiotic stresses in plants. In the current study, we isolated two ATG5 homologs genes, namely, MdATG5a and MdATG5b, from apple, demonstrating their responsiveness to drought and oxidative stresses. In addition to having the same cellular localization in the nucleus and cytoplasm, both MdATG5a and MdATG5b could interact with MdATG12. Transgenic apple plants overexpressing MdATG5a exhibited an improved drought tolerance, as indicated by less drought-related damage and higher photosynthetic capacities compared to wild-type (WT) plants under drought stress. The overexpression of MdATG5a improved antioxidant defenses in apple when exposed to drought via elevating both antioxidant enzyme activities and the levels of beneficial antioxidants. Furthermore, under drought stress, the overexpression of MdATG5a promoted the mobilization of starch to accumulate greater levels of soluble sugars, contributing to osmotic adjustments and supporting carbon skeletons for proline synthesis. Such changes in physiological responses may be associated with increased autophagic activities in the transgenic plants upon exposure to drought. Our results demonstrate that MdATG5a-mediated autophagy enhances drought tolerance of apple plants via improving antioxidant defenses and metabolic adjustments.


Assuntos
Antioxidantes/metabolismo , Desidratação/genética , Desidratação/fisiopatologia , Secas , Malus/genética , Malus/fisiologia , Amido/metabolismo , Produtos Agrícolas/genética , Produtos Agrícolas/fisiologia , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Variação Genética , Genótipo , Estresse Oxidativo/genética , Estresse Oxidativo/fisiologia , Plantas Geneticamente Modificadas , Amido/genética
2.
Int J Mol Sci ; 22(15)2021 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-34360688

RESUMO

Plant response to osmotic stress is a complex issue and includes a wide range of physiological and biochemical processes. Extensive studies of known cultivars and their reaction to drought or salinity stress are very important for future breeding of new and tolerant cultivars. Our study focused on the antioxidant activity, accumulations of osmotica, and the content of abscisic acid in apple (cv. "Malinové holovouské", "Fragrance", "Rubinstep", "Idared", "Car Alexander") and cherry (cv. "Regina", "Napoleonova", "Kastánka", "Sunburst", "P-HL-C") cultivated in vitro on media containing different levels of polyethylene glycol PEG-6000. Our results indicated that the studied genotypes responded differently to osmotic stress manifested as reduction in the leaf relative water content (RWC) and increment in the activities of antioxidant enzymes, proline, sugars, and abscisic acid content. Overall, cherry cultivars showed a smaller decrease in percentage RWC and enzymatic activities, but enhanced proline content compared to the apple plants cultivars. Cultivars "Rubinstep", "Napoleonova", and "Kastánka" exhibited higher antioxidant capacity and accumulation of osmoprotectants like proline and sorbitol that can be associated with the drought-tolerance system.


Assuntos
Ácido Abscísico/análise , Antioxidantes/análise , Pressão Osmótica , Prolina/análise , Estresse Fisiológico , Açúcares/análise , Malus/química , Malus/metabolismo , Malus/fisiologia , Prolina/metabolismo , Prunus avium/química , Prunus avium/metabolismo , Prunus avium/fisiologia , Açúcares/metabolismo
3.
Int J Mol Sci ; 22(11)2021 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-34073724

RESUMO

Water deficit adversely affects apple (Malus domestica) productivity on the Loess Plateau. Autophagy plays a key role in plant responses to unfavorable environmental conditions. Previously, we demonstrated that a core apple autophagy-related protein, MdATG8i, was responsive to various stresses at the transcript level. Here, we investigated the function of this gene in the response of apple to severe drought and found that its overexpression (OE) significantly enhanced drought tolerance. Under drought conditions, MdATG8iOE apple plants exhibited less drought-related damage and maintained higher photosynthetic capacities compared with the wild type (WT). The accumulation of ROS (reactive oxygen species) was lower in OE plants under drought stress and was accompanied by higher activities of antioxidant enzymes. Besides, OE plants accumulated lower amounts of insoluble or oxidized proteins but greater amounts of amino acids and flavonoid under severe drought stress, probably due to their enhanced autophagic activities. Particularly, MdATG8iOE plants showed higher root hydraulic conductivity than WT plants did under drought conditions, indicating the enhanced ability of water uptake. In summary, the overexpression of MdATG8i alleviated oxidative damage, modulated amino acid metabolism and flavonoid synthesis, and improved root water uptake, ultimately contributing to enhanced drought tolerance in apple.


Assuntos
Família da Proteína 8 Relacionada à Autofagia/metabolismo , Secas , Malus/metabolismo , Estresse Oxidativo , Estresse Fisiológico , Autofagia , Flavonoides/biossíntese , Regulação da Expressão Gênica de Plantas , Malus/genética , Malus/fisiologia , Plantas Geneticamente Modificadas
4.
Opt Express ; 29(8): 12381-12397, 2021 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-33984999

RESUMO

We present a multi-species trace gas sensor based on a fast, compact home-built Fourier transform spectrometer (FTS) combined with a broadband mid-infrared supercontinuum (SC) source. The spectrometer covers the spectral bandwidth of the SC source (2 - 4 µm) and provides a best spectral resolution of 1 GHz in 6 seconds. It has a detection sensitivity of a few hundred of ppbv Hz-1/2 for different gas species. We study the performance of the developed spectrometer in terms of precision, linearity, long-term stability, and multi-species detection. We use the spectrometer for measuring fruit-produced volatiles under different atmospheric conditions and compare the performance with a previously developed scanning grating-based spectrometer.


Assuntos
Gases/análise , Malus/química , Malus/fisiologia , Espectroscopia de Infravermelho com Transformada de Fourier/instrumentação , Acetaldeído/análise , Acetatos/análise , Acetona/análise , Desenho de Equipamento , Etano/análise , Etanol/análise , Etilenos/análise , Análise de Fourier , Metanol/análise , Espectroscopia de Infravermelho com Transformada de Fourier/métodos
5.
Plant Sci ; 306: 110850, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33775357

RESUMO

Autophagy is a major degradation pathway in plants for maintaining cellular homeostasis in response to various environmental stressors. ATG8 is one of a series of autophagy-related (ATG) proteins and plays a central role in both bulk and selective autophagy. Previously, we characterized MdATG8i in apple and demonstrated that it has a positive role in apple stress resistance. Although many ATG8-interacting proteins have been found in Arabidopsis, no protein has been reported to interact with MdATG8 in apple. Here, we identified MdHARBI1 as a MdATG8i-interacting protein in apple, however, the functions of HARBI1-like proteins have not been explored in plants. Expression analysis of MdHARBI1 and pro-MdHARBI1-GUS staining of transgenic Arabidopsis exposed to high temperature demonstrated that MdHARBI1 was significantly induced by heat stress. Moreover, heat-treated MdHARBI1-trangenic tomato plants maintained higher autophagic activity, accumulated fewer ROS, and displayed stronger chlorophyll fluorescence than wild-type plants. Because these phenotypes were consistent with those displayed by MdATG8i-overexpressing apple plants under high temperature, we concluded that the MdATG8i-interacting protein MdHARBI1 plays a critical role in the basal thermotolerance of plants, mainly by influencing autophagy pathways.


Assuntos
Proteínas Relacionadas à Autofagia/fisiologia , Autofagia/genética , Resposta ao Choque Térmico/genética , Malus/genética , Malus/fisiologia , Termotolerância/genética , Termotolerância/fisiologia , Autofagia/fisiologia , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Resposta ao Choque Térmico/fisiologia , Proteínas de Plantas/genética , Proteínas de Plantas/fisiologia
6.
Plant Sci ; 305: 110824, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33691959

RESUMO

Apple (Malus domestica) exhibits classic S-RNase-mediated gametophytic self-incompatibility. Previous studies have shown that the S-RNase secreted from style cells could trigger signal transduction and defense responses mediated by Ca2+ and reactive oxygen species (ROS) after entering into the pollen tube. In this study, we investigated the downstream genes activated by ROS during S-RNase-mediated gametophytic self-incompatibility in pollen tubes. A substantial increase in ROS, as well as up-regulated expression of a serine-threonine protein kinase gene, OXIDATIVE SIGNAL-INDUCIBLE1 (MdOXI1), was detected in apple pollen tubes treated with self-S-RNase. A kinase assay-linked phosphoproteomics (KALIP) analysis suggested that MdOXI1 could bind and phosphorylate the downstream protein kinase Pto-interacting protein 1-like (MdPTI1L). The phosphorylation level of MdPTI1L was significantly reduced after silencing MdOXI1 with antisense oligonucleotides in the pollen tube. Silencing of either MdOXI1 or MdPTI1L alleviated the inhibitory effect of self-S-RNase on pollen tube growth. Our results thus indicate that MdPTI1L is phosphorylated by MdOXI1 in the pollen tube and participates in the ROS signaling pathway triggered by S-RNase.


Assuntos
Malus/genética , Malus/fisiologia , Fosforilação/fisiologia , Fosfotransferases/metabolismo , Tubo Polínico/crescimento & desenvolvimento , Tubo Polínico/genética , Transdução de Sinais/fisiologia , Produtos Agrícolas/genética , Produtos Agrícolas/fisiologia , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Variação Genética , Genótipo , Polinização/fisiologia , Espécies Reativas de Oxigênio/metabolismo , Ribonucleases/metabolismo
7.
PLoS One ; 16(2): e0245487, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33606701

RESUMO

Many apple cultivars are subject to biennial fluctuations in flowering and fruiting. It is believed that this phenomenon is caused by a repressive effect of developing fruit on the initiation of flowers in the apex of proximal bourse shoots. However, the genetic pathways of floral initiation are incompletely described in apple, and the biological nature of floral repression by fruit is currently unknown. In this study, we characterized the transcriptional landscape of bourse shoot apices in the biennial cultivar, 'Honeycrisp', during the period of floral initiation, in trees bearing a high fruit load and in trees without fruit. Trees with high fruit load produced almost exclusively vegetative growth in the subsequent year, whereas the trees without fruit produced flowers on the majority of the potential flowering nodes. Using RNA-based sequence data, we documented gene expression at high resolution, identifying >11,000 transcripts that had not been previously annotated, and characterized expression profiles associated with vegetative growth and flowering. We also conducted a census of genes related to known flowering genes, organized the phylogenetic and syntenic relationships of these genes, and compared expression among homeologs. Several genes closely related to AP1, FT, FUL, LFY, and SPLs were more strongly expressed in apices from non-bearing, floral-determined trees, consistent with their presumed floral-promotive roles. In contrast, a homolog of TFL1 exhibited strong and persistent up-regulation only in apices from bearing, vegetative-determined trees, suggesting a role in floral repression. Additionally, we identified four GIBBERELLIC ACID (GA) 2 OXIDASE genes that were expressed to relatively high levels in apices from bearing trees. These results define the flowering-related transcriptional landscape in apple, and strongly support previous studies implicating both gibberellins and TFL1 as key components in repression of flowering by fruit.


Assuntos
Flores , Frutas , Regulação da Expressão Gênica de Plantas , Malus , Brotos de Planta/fisiologia , Flores/genética , Flores/fisiologia , Frutas/genética , Frutas/fisiologia , Malus/genética , Malus/fisiologia , Proteínas de Plantas/genética
8.
Plant J ; 106(2): 379-393, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33497017

RESUMO

Cold stress has always been a major abiotic factor affecting the yield and quality of temperate fruit crops. Ethylene plays a critical regulatory role in the cold stress response, but the underlying molecular mechanisms remain elusive. Here, we revealed that ethylene positively modulates apple responses to cold stress. Treatment with 1-aminocyclopropane-1-carboxylate (an ethylene precursor) and aminoethoxyvinylglycine (an ethylene biosynthesis inhibitor) respectively increased and decreased the cold tolerance of apple seedlings. Consistent with the positive effects of ethylene on cold stress responses, a low-temperature treatment rapidly induced ethylene release and the expression of MdERF1B, which encodes an ethylene signaling activator, in apple seedlings. Overexpression of MdERF1B significantly increased the cold tolerance of apple plant materials (seedlings and calli) and Arabidopsis thaliana seedlings. A quantitative real-time PCR analysis indicated that MdERF1B upregulates the expression of the cold-responsive gene MdCBF1 in apple seedlings. Moreover, MdCIbHLH1, which functions upstream of CBF-dependent pathways, enhanced the binding of MdERF1B to target gene promoters as well as the consequent transcriptional activation. The stability of MdERF1B-MdCIbHLH1 was affected by cold stress and ethylene. Furthermore, MdERF1B interacted with the promoters of two genes critical for ethylene biosynthesis, MdACO1 and MdERF3. The resulting upregulated expression of these genes promoted ethylene production. However, the downregulated MdCIbHLH1 expression in MdERF1B-overexpressing apple calli significantly inhibited ethylene production. These findings imply that MdERF1B-MdCIbHLH1 is a potential regulatory module that integrates the cold and ethylene signaling pathways in apple.


Assuntos
Etilenos/metabolismo , Malus/metabolismo , Reguladores de Crescimento de Plantas/fisiologia , Resposta ao Choque Frio , Malus/fisiologia , Reguladores de Crescimento de Plantas/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/fisiologia , Reação em Cadeia da Polimerase em Tempo Real , Plântula/metabolismo , Plântula/fisiologia
9.
BMC Plant Biol ; 21(1): 52, 2021 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-33468049

RESUMO

BACKGROUND: Soil salinity is a critical threat to global agriculture. In plants, the accumulation of xanthine activates xanthine dehydrogenase (XDH), which catalyses the oxidation/conversion of xanthine to uric acid to remove excess reactive oxygen species (ROS). The nucleobase-ascorbate transporter (NAT) family is also known as the nucleobase-cation symporter (NCS) or AzgA-like family. NAT is known to transport xanthine and uric acid in plants. The expression of MdNAT is influenced by salinity stress in apple. RESULTS: In this study, we discovered that exogenous application of xanthine and uric acid enhanced the resistance of apple plants to salinity stress. In addition, MdNAT7 overexpression transgenic apple plants showed enhanced xanthine and uric acid concentrations and improved tolerance to salinity stress compared with nontransgenic plants, while opposite phenotypes were observed for MdNAT7 RNAi plants. These differences were probably due to the enhancement or impairment of ROS scavenging and ion homeostasis abilities. CONCLUSION: Our results demonstrate that xanthine and uric acid have potential uses in salt stress alleviation, and MdNAT7 can be utilized as a candidate gene to engineer resistance to salt stress in plants.


Assuntos
Malus/fisiologia , Proteínas de Plantas/genética , Tolerância ao Sal/fisiologia , Ácido Úrico/farmacologia , Xantina/farmacologia , Antioxidantes/análise , Antioxidantes/metabolismo , Regulação da Expressão Gênica de Plantas , Homeostase , Peróxido de Hidrogênio/metabolismo , Malus/efeitos dos fármacos , Malus/genética , Proteínas de Transporte de Nucleobases/genética , Proteínas de Transporte de Nucleobases/metabolismo , Folhas de Planta/química , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/genética , Potássio/análise , Tolerância ao Sal/efeitos dos fármacos , Sódio/análise , Ácido Úrico/análise , Xantina/análise
10.
Plant J ; 105(1): 62-78, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33095963

RESUMO

Fruits are complex organs that are spatially regulated during development. Limited phenotyping capacity at cell and tissue levels is one of the main obstacles to our understanding of the coordinated regulation of the processes involved in fruit growth and quality. In this study, the spatial evolution of biophysical and metabolic traits of peach and apple fruit was investigated during fruit development. In parallel, the multi-exponential relaxation times and apparent microporosity were assessed by quantitative magnetic resonance imaging (MRI). The aim was to identify the possible relationships between MRI parameters and variations in the structure and composition of fruit tissues during development so that transverse relaxation could be proposed as a biomarker for the assessment of the structural and functional evolution of fruit tissues during growth. The study provides species-specific data on developmental and spatial variations in density, cell number and size distribution, insoluble and soluble compound accumulation and osmotic and water potential in the fruit mesocarp. Magnetic resonance imaging was able to capture tissue evolution and the development of pericarp heterogeneity by accessing information on cell expansion, water status and distribution at cell level, and microporosity. Changes in vacuole-related transverse relaxation rates were mostly explained by cell/vacuole size. The impact of cell solute composition, microporosity and membrane permeability on relaxation times is also discussed. The results demonstrate the usefulness of MRI as a tool to phenotype fruits and to access important physiological data during development, including information on spatial variability.


Assuntos
Frutas/anatomia & histologia , Malus/anatomia & histologia , Prunus persica/anatomia & histologia , Frutas/metabolismo , Frutas/fisiologia , Imageamento por Ressonância Magnética , Malus/metabolismo , Malus/fisiologia , Prunus persica/metabolismo , Prunus persica/fisiologia
11.
New Phytol ; 229(5): 2707-2729, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33119890

RESUMO

The plant hormone jasmonic acid (JA) is involved in the cold stress response, and the inducer of CBF expression 1 (ICE1)- C-repeat binding factor (CBF) regulatory cascade plays a key role in the regulation of cold stress tolerance. In this study, we showed that a novel B-box (BBX) protein MdBBX37 positively regulates JA-mediated cold-stress resistance in apple. We found that MdBBX37 bound to the MdCBF1 and MdCBF4 promoters to activate their transcription, and also interacted with MdICE1 to enhance the transcriptional activity of MdICE1 on MdCBF1, thus promoting its cold tolerance. Two JA signaling repressors, MdJAZ1 and MdJAZ2 (JAZ, JAZMONATE ZIM-DOMAIN), interacted with MdBBX37 to repress the transcriptional activity of MdBBX37 on MdCBF1 and MdCBF4, and also interfered with the interaction between MdBBX37 and MdICE1, thus negatively regulating JA-mediated cold tolerance. E3 ligase MdMIEL1 (MIEL1, MYB30-Interacting E3 Ligase1) reduced MdBBX37-improved cold resistance by mediating ubiquitination and degradation of the MdBBX37 protein. The data reveal that MIEL1 and JAZ proteins co-regulate JA-mediated cold stress tolerance through the BBX37-ICE1-CBF module in apple. These results will aid further examination of the post-translational modification of BBX proteins and the regulatory mechanism of JA-mediated cold stress tolerance.


Assuntos
Resposta ao Choque Frio , Malus , Proteínas de Plantas/genética , Ciclopentanos , Regulação da Expressão Gênica de Plantas , Malus/genética , Malus/fisiologia , Oxilipinas , Ubiquitinação
12.
Plant J ; 105(4): 1026-1034, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33211343

RESUMO

Ectopic expression of the apple 2-oxoglutarate-dependent dioxygenase (DOX, 2ODD) gene, designated MdDOX-Co, is thought to cause the columnar shape of apple trees. However, the mechanism underlying the formation of such a unique tree shape remains unclear. To solve this problem, we demonstrated that Arabidopsis thaliana overexpressing MdDOX-Co contained reduced levels of biologically active gibberellin (GA) compared with wild type. In summary: (i) with biochemical approaches, the gene product MdDOX-Co was shown to metabolize active GA A4 (GA4 ) to GA58 (12-OH-GA4 ) in vitro. MdDOX-Co also metabolized its precursors GA12 and GA9 to GA111 (12-OH-GA12 ) and GA70 (12-OH-GA9 ), respectively; (ii) Of the three 12-OH-GAs, GA58 was still active physiologically, but not GA70 or GA111 ; (iii) Arabidopsis MdDOX-Co OE transformants converted exogenously applied deuterium-labeled (d2 )-GA12 to d2 -GA111 but not to d2 -GA58 , whereas transformants converted applied d2 -GA9 to d2 -GA58 ; (iv) GA111 is converted poorly to GA70 by GA 20-oxidases in vitro when GA12 is efficiently metabolized to GA9 ; (v) no GA58 was detected endogenously in MdDOX-Co OE transformants. Overall, we conclude that 12-hydroxylation of GA12 by MdDOX-Co prevents the biosynthesis of biologically active GAs in planta, resulting in columnar phenotypes.


Assuntos
Genes de Plantas/genética , Giberelinas/metabolismo , Malus/genética , Reguladores de Crescimento de Plantas/metabolismo , Árvores/genética , Arabidopsis , Dioxigenases/metabolismo , Genes de Plantas/fisiologia , Ácidos Cetoglutáricos/metabolismo , Malus/crescimento & desenvolvimento , Malus/metabolismo , Malus/fisiologia , Reguladores de Crescimento de Plantas/fisiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Proteínas de Plantas/fisiologia , Plantas Geneticamente Modificadas , Árvores/crescimento & desenvolvimento , Árvores/metabolismo , Árvores/fisiologia
13.
Food Chem ; 339: 128151, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33152896

RESUMO

The effects of aloe vera (Aloe vera (L.) Burm. f.) gel treatment on the incidence of superficial scald in 'Starking' apples (Malus domestica Borkh. Var. Starking) during cold storage were studied. Apples were harvested at the pre-climacteric stage and treated with aloe vera gel. The treatment increased malondialdehyde content and membrane lipid damage. Furthermore, it inhibited the release of ethylene at the early stage but increased it in the later stage. The expression level of ACC synthase 1 (MdACS1) also increased, and the antioxidant capacity in apples, particularly, catalase, peroxidase, and superoxide dismutase activities, all decreased, while concomitantly, the content of α-farnesene and its oxidation product, conjugated triene increased, thereby aggravating superficial scald incidence during storage at low temperature.


Assuntos
Conservação de Alimentos/métodos , Malus/fisiologia , Preparações de Plantas , Antioxidantes/metabolismo , Temperatura Baixa , Ciclopropanos/farmacologia , Enzimas/metabolismo , Etilenos/metabolismo , Armazenamento de Alimentos , Frutas/fisiologia , Malus/efeitos dos fármacos , Oxirredução , Preparações de Plantas/farmacologia , Proteínas de Plantas/metabolismo , Sesquiterpenos/metabolismo
14.
Plant Cell Rep ; 40(2): 405-419, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33331953

RESUMO

KEY MESSAGE: The ankyrin repeat-containing protein MdANK2B was identified to contribute to increasing resistance to salt stress and decreasing sensitivity to ABA in Malus domestica. Ankyrin (ANK) repeat-containing proteins occur widely in prokaryotes, eukaryotes, and even in some viruses and play a critical role in plant growth and development, as well as the response to biotic and abiotic stress. However, the function of ANK repeat-containing proteins in apple (Malus domestica) has not yet been investigated. Here, we identified apple MdANK2B based on homology analysis with the Arabidopsis ANK repeat-containing proteins AtAKR2A and AtAKR2B. MdANK2B was found to be localized in the cytoplasm, and its encoding gene was highly expressed in both apple leaves and fruits. In addition, MdANK2B gene expression was highly induced by salt stresses and abscisic acid (ABA). Overexpression of MdANK2B increased resistance to salt stress and decreased sensitivity to ABA in both transgenic apple calli and seedlings. In addition, overexpression of MdANK2B reduced the accumulation of reactive oxygen species (ROS) by enhancing the activity of antioxidant enzymes in response to salt stress. Our data revealed the role of MdANK2B in response to salt stress and ABA treatment in apple, which widens the known functions of ANK repeat-containing proteins in response to abiotic stress.


Assuntos
Ácido Abscísico/farmacologia , Repetição de Anquirina/genética , Proteínas de Arabidopsis/genética , Malus/genética , Chaperonas Moleculares/genética , Reguladores de Crescimento de Plantas/farmacologia , Proteínas de Plantas/metabolismo , Expressão Gênica , Malus/fisiologia , Proteínas de Plantas/genética , Espécies Reativas de Oxigênio/metabolismo , Estresse Salino , Tolerância ao Sal/genética , Estresse Fisiológico
15.
Plant Sci ; 301: 110654, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33218625

RESUMO

Myo-inositol and its derivatives play vital roles in plant stress tolerance. Myo-inositol-1-phosphate synthase (MIPS) is the rate-limiting enzyme of myo-inositol biosynthesis. However, the role of apple MIPS-mediated myo-inositol biosynthesis in stress tolerance remains elusive. In this study, we found that ectopic expression of MdMIPS1 from apple increased myo-inositol content and enhanced tolerance to salt and osmotic stresses in transgenic Arabidopsis lines. In transgenic apple lines over-expressing MdMIPS1, the increased myo-inositol levels could promote accumulation of other osmoprotectants such as glucose, sucrose, galactose, and fructose, to alleviate salinity-induced osmotic stress. Also, it was shown that overexpression of MdMIPS1 enhanced salinity tolerance by improving the antioxidant system to scavenge ROS, as well as Na+ and K+ homeostasis. Taken together, our results revealed a protective role of MdMIPS1-mediated myo-inositol biosynthesis in salt tolerance by improving osmotic balance, antioxidant defense system, and ion homeostasis in apple.


Assuntos
Antioxidantes/metabolismo , Malus/genética , Mio-Inositol-1-Fosfato Sintase/metabolismo , Tolerância ao Sal/genética , Arabidopsis/genética , Arabidopsis/fisiologia , Expressão Gênica , Regulação da Expressão Gênica de Plantas , Inositol/metabolismo , Íons/metabolismo , Malus/fisiologia , Mio-Inositol-1-Fosfato Sintase/genética , Osmose , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Salinidade , Estresse Fisiológico
16.
Plant Sci ; 301: 110689, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33218647

RESUMO

Drought stress is a severe source of abiotic stress that can affect apple yield and quality, yet the underlying molecular mechanism of the drought stress response and the role of MdBT2 in the process remain unclear. Here, we find that MdBT2 negatively regulates the drought stress response. Both in vivo and in vitro assays indicated that MdBT2 interacted physically with and ubiquitinated MdNAC143, a member of the NAC TF family that is a positive regulator under drought stress. In addition, MdBT2 promotes the degradation of MdNAC143 via the 26S proteasome system. A series of transgenic assays in apple calli and Arabidopsis verify that MdBT2 confers susceptibility to drought stress at least in part by the regulation of MdNAC143. Overall, our findings provide new insight into the mechanism of MdBT2, which functions antagonistically to MdNAC143 in regulating drought stress by regulating the potential downstream target protein MdNAC143 for proteasomal degradation in apple.


Assuntos
Malus/genética , Proteínas de Plantas/metabolismo , Arabidopsis/genética , Arabidopsis/fisiologia , Secas , Regulação da Expressão Gênica de Plantas , Malus/fisiologia , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas , Estresse Fisiológico , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
17.
Sci Rep ; 10(1): 16958, 2020 10 12.
Artigo em Inglês | MEDLINE | ID: mdl-33046738

RESUMO

Pollination services from animals are critical for both crop production and reproduction in wild plant species. Accurately measuring the relative contributions of different animal taxa to pollination service delivery is essential for identifying key pollinators. However, widely used measures of pollinator effectiveness (e.g., single visit pollen deposition) may be inaccurate where plant reproduction is strongly constrained by pollen quality. Here, we test the efficacy of single and multiple pollinator visits for measuring pollinator performance in a model plant species (apple, Malus domestica Borkh) that is strongly limited by pollen quality. We determined pollination success using a suite of measures (pollen deposition, pollen tube growth, fruit and seed set) from single and multiple pollinator visits. We found that pollen deposition from a single pollinator visit seldom resulted in the growth of pollen tubes capable of eliciting ovule fertilisation and never resulted in fruit or seed production. In contrast, multiple pollinator visits frequently initiated the growth of pollen tubes capable of ovule fertilisation and often led to fruit and seed production. Our findings suggest that single visit pollen deposition may provide a poor measure of pollinator performance when linked to reproductive success of plant species that are constrain by pollen quality. Alternatively, pollen tube growth from single and multiple pollinator visits can provide a measure of pollinator performance that is more closely linked to plant reproduction.


Assuntos
Abelhas/fisiologia , Malus/fisiologia , Tubo Polínico/crescimento & desenvolvimento , Pólen/fisiologia , Polinização/fisiologia , Reprodução/fisiologia , Animais
18.
Plant Sci ; 299: 110611, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32900448

RESUMO

Abiotic stresses threaten the productivity and quality of economically important perennial fruit crops such as apple (Malus × domestica Borkh.). WRKY transcription factors play various roles in plant responses to abiotic stress, but little is known regarding WRKY genes in apple. Here, we carried out functional characterization of an apple Group IIa WRKY gene (MdWRKY30). qRT-PCR analysis found that MdWRKY30 expression was induced by salt and drought stress. A subcellular localization assay showed that MdWRKY30 is localized to the nucleus. A transactivation assay found that MdWRKY30 has no transcriptional activation activity. A Y2H assay indicated that MdWRKY26, MdWRKY28, and MdWRKY30 interact with each other to form heterodimers and homodimers. Transgenic analysis revealed that the overexpression of MdWRKY30 in Arabidopsis enhanced salt and osmotic tolerance in the seedling stage, as well as during the seed germination and greening cotyledon stages. MdWRKY30 overexpression enhanced tolerance to salt and osmotic stresses in transgenic apple callus through transcriptional regulation of stress-related genes. Together, our results demonstrate that MdWRKY30 is an important regulator of salinity and osmotic stress tolerance in apple.


Assuntos
Arabidopsis/fisiologia , Malus/fisiologia , Pressão Osmótica , Proteínas de Plantas/genética , Tolerância ao Sal/genética , Fatores de Transcrição/genética , Sequência de Aminoácidos , Arabidopsis/genética , Malus/genética , Filogenia , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/fisiologia , Plântula/crescimento & desenvolvimento , Plântula/fisiologia , Alinhamento de Sequência , Fatores de Transcrição/química , Fatores de Transcrição/metabolismo
19.
Plant Cell Rep ; 39(12): 1687-1703, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32959122

RESUMO

KEY MESSAGE: Cytokinin together with MdoBRR1, MdoBRR8 and MdoBRR10 genes participate in the downregulation of MdoDAM1, contributing to the transition from endo- to ecodormancy in apple buds. The final step of cytokinin (CK) signaling pathway culminates in the activation of type-B response regulators (BRRs), important transcriptional factors in the modulation of CK-responsive genes. In this study, we performed a genome-wide analysis aiming to identify apple BRR family members and understand their involvement in bud dormancy control. The investigation identified ten MdoBRR protein-coding genes. A higher expression of three MdoBRR (MdoBRR1, MdoBRR9 and MdoBRR10) was observed in dormant buds in comparison to other developmental stages. Interestingly, in ecodormant buds these three MdoBRR genes were upregulated in a CK-dependent manner. Transcription profiles, determined during dormancy cycle under field and artificially controlled conditions, revealed that MdoBRR1 and MdoBRR8 played important roles in the transition from endo- to ecodormancy, probably mediated by endogenous CK stimuli. The expression of MdoBRR7, MdoBRR9, and MdoBRR10 was induced in ecodormant buds exposed to warm temperatures, indicating a putative role in growth resumption after chilling requirement fulfillment. Contrasting expression patternsin vivo between MdoBRRs and MdoDAM1, an essential dormancy establishment regulator, were observed during dormancy cycle and in CK-treated buds. Thereafter, in vivo transactivation assays showed that CK stimuli combined with transient overexpression of MdoBRR1, MdoBRR8, and MdoBRR10 resulted in downregulation of the reporter gene gusA driven by the MdoDAM1 promoter. These pieces of evidences point to the integration of CK-triggered responses through MdoBRRs that are able to downregulate MdoDAM1, contributing to dormancy release in apple.


Assuntos
Citocininas/fisiologia , Malus/fisiologia , Dormência de Plantas/fisiologia , Proteínas de Plantas/genética , Arabidopsis/genética , Citocininas/farmacologia , Regulação da Expressão Gênica de Plantas , Malus/efeitos dos fármacos , Malus/crescimento & desenvolvimento , Filogenia , Dormência de Plantas/efeitos dos fármacos , Reguladores de Crescimento de Plantas/metabolismo , Reguladores de Crescimento de Plantas/farmacologia , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas
20.
Plant Physiol ; 184(3): 1273-1290, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32958560

RESUMO

Drought is an important environmental factor affecting the growth and production of agricultural crops and fruits worldwide, including apple (Malus domestica). Heat shock factors (HSFs) have well-documented functions in stress responses, but their roles in flavonoid synthesis and the flavonoid-mediated drought response mechanism remain elusive. In this study, we demonstrated that a drought-responsive HSF, designated MdHSFA8a, promotes the accumulation of flavonoids, scavenging of reactive oxygen species, and plant survival under drought conditions. A chaperone, HEAT SHOCK PROTEIN90 (HSP90), interacted with MdHSFA8a to inhibit its binding activity and transcriptional activation. However, under drought stress, the MdHSP90-MdHSFA8a complex dissociated and the released MdHSFA8a further interacted with the APETALA2/ETHYLENE RESPONSIVE FACTOR family transcription factor RELATED TO AP2.12 to activate downstream gene activity. In addition, we demonstrated that MdHSFA8a participates in abscisic acid-induced stomatal closure and promotes the expression of abscisic acid signaling-related genes. Collectively, these findings provide insight into the mechanism by which stress-inducible MdHSFA8a modulates flavonoid synthesis to regulate drought tolerance.


Assuntos
Ácido Abscísico , Flavonoides/biossíntese , Flavonoides/genética , Resposta ao Choque Térmico/genética , Resposta ao Choque Térmico/fisiologia , Malus/genética , Malus/fisiologia , Estresse Fisiológico/genética , Ácido Abscísico/metabolismo , Produtos Agrícolas/genética , Produtos Agrícolas/fisiologia , Secas , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Plantas Geneticamente Modificadas
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