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1.
BMC Plant Biol ; 21(1): 469, 2021 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-34645384

RESUMO

BACKGROUND: Decrease in anthocyanin content results in the loss of red color in leaves, petals and receptacles during development. The content of anthocyanin was affected by the biosynthesis and degradation of anthocyanin. Compared with the known detailed mechanism of anthocyanin biosynthesis, the degradation mechanism is not fully investigated. It is vital to study the degradation mechanism of anthocyanin in pear for promoting the accumulation of anthocyanin and inhibiting the red fading in pear. RESULTS: Here, we reported that laccase encoded by PbLAC4-like was associated with anthocyanin degradation in pear. The expression pattern of PbLAC4-like was negatively correlated with the content of anthocyanin during the color fading process of pear leaves, petals and receptacles. Phylogenetic analysis and sequence alignment revealed that PbLAC4-like played a vital role in anthocyanin degradation. Thus, the degradation of anthocyanin induced by PbLAC4-like was further verified by transient assays and prokaryotic expression. More than 80% of anthocyanin compounds were degraded by transiently over-expressed PbLAC4-like in pear fruitlet peel. The activity of crude enzyme to degrade anthocyanin in leaves at different stages was basically consistent with the expression of PbLAC4-like. The anthocyanin degradation ability of prokaryotic induced PbLAC4-like protein was also verified by enzyme activity assay. Besides, we also identified PbMYB26 as a positive regulator of PbLAC4-like. Yeast one-hybrid and dual luciferase assay results showed that PbMYB26 activated PbLAC4-like expression by directly binding to the PbLAC4-like promoter. CONCLUSIONS: Taken together, the PbLAC4-like activated by PbMYB26, was involved in the degradation of anthocyanin, resulting in the redness fading in different pear tissues.

2.
Plant Physiol ; 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34618120

RESUMO

Water deficit is one of the main challenges for apple (Malus × domestica) growth and productivity. Breeding drought-tolerant cultivars depends on a thorough understanding of the drought responses of apple trees. Here, we identified the zinc-finger protein B-BOX 7/CONSTANS-LIKE 9 (MdBBX7/MdCOL9), which plays a positive role in apple drought tolerance. The overexpression of MdBBX7 enhanced drought tolerance, whereas knocking down MdBBX7 expression reduced it. Chromatin immunoprecipitation-sequencing (ChIP-seq) analysis identified one cis-element of MdBBX7, CCTTG, as well as its known binding motif, the T/G box. ChIP-seq and RNA-seq identified 1,197 direct targets of MdBBX7, including ETHYLENE RESPONSE FACTOR (ERF1), EARLY RESPONSIVE TO DEHYDRATION 15 (ERD15), and GOLDEN2-LIKE 1 (GLK1) and these were further verified by ChIP-qPCR and electronic mobility shift assays. Yeast two-hybrid screen identified an interacting protein of MdBBX7, RING-type E3 ligase MYB30-INTERACTING E3 LIGASE 1 (MIEL1). Further examination revealed that MdMIEL1 could mediate the ubiquitination and degradation of MdBBX7 by the 26S proteasome pathway. Genetic interaction analysis suggested that MdMIEL1 acts as an upstream factor of MdBBX7. In addition, MdMIEL1 was a negative regulator of the apple drought stress response. Taken together, our results illustrate the molecular mechanisms by which the MdMIEL1-MdBBX7 module influences the response of apple to drought stress.

3.
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.

4.
Plant Physiol Biochem ; 168: 83-92, 2021 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-34627025

RESUMO

As RNA chaperones, cold shock proteins (CSPs) are essential for cold adaptation. Although the functions of CSPs in cold response have been demonstrated in several species, the roles of CSPs in response to drought are largely unknown. Here, we demonstrated that MdCSP3, a downstream target gene of MdMYB88 and MdMYB124, contributes to drought tolerance in apple (Malus × domestica). MdCSP3 responds to various abiotic stresses, including drought, cold, heat, and salt stress. Compared with non-transgenic apple GL-3, the MdCSP3 overexpressing plants exhibit significantly lower drought resistance and a reduced capacity for ROS scavenging by the regulation of antioxidant enzymes SOD, CAT, and POD. Additionally, RNA-seq data shows that MdCSP3 regulates expression of genes involved in oxidative stress response. Taken together, our results demonstrate the functions of MdCSP3 in apple drought tolerance, and this finding provides a new direction for breeding of drought resistant apple.

5.
J Exp Bot ; 2021 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-34486649

RESUMO

The high accumulation of phloridzin makes apple (Malus domestica) unique in the plant kingdom, which suggests a vital role of its biosynthesis in the physiological processes of apple. In our previous study, silencing MdUGT88F1 (a key UDP-glucose: phloretin 2'-O-glucosyltransferase gene) revealed the importance of phloridzin biosynthesis in apple development and Valsa canker resistance. Here, results from MdUGT88F1-silencing lines showed that phloridzin biosynthesis was indispensable for normal chloroplast development and photosynthetic carbon fixation by maintaining MdGLK1/2 expression. Interestingly, the increased phloridzin biosynthesis didn't affect plant (or chloroplast) development but reduced nitrogen accumulation, leading to chlorophyll deficiency, light sensitivity, and sugar accumulation in MdUGT88F1-overexpressing apple lines during their growth and development. Further analysis revealed that MdUGT88F1-mediated phloridzin biosynthesis negatively regulated cytosolic glutamine synthetase1-asparagine synthetase-asparaginase (GS1-AS-ASPG) pathway of ammonium assimilation and limited chlorophyll synthesis in the shoots of apple. The interference of phloridzin biosynthesis in the GS1-AS-ASPG pathway was also assumed to be associated with its limitation of the carbon skeletons of ammonium assimilation through metabolic competition with the tricarboxylic acid cycle. Taken together, our findings shed light on the role of MdUGT88F1-mediated phloridzin biosynthesis in the coordination between carbon and nitrogen accumulation in apple trees.

6.
Ecotoxicol Environ Saf ; 225: 112734, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34482065

RESUMO

Cadmium (Cd), a phytotoxic heavy metal accumulated in plants and fruits, has significant adverse effects on plant growth and development as well as human health. In particular, Cd pollution has become a serious agricultural issue in recent years. Apple is one of the most popular fruits consumed at the global scale. Improving apple Cd resistance via reductions in Cd absorption can benefit apple tree growth and ensure fruit safety. In this study, we determined that, under the 200 µM Cd treatment, 35S::MdIAA24 apple plants exhibited more biomass and less Cd accumulation in the tested tissues compared to wild type (WT). Furthermore, the 35S::MdIAA24 apple plants demonstrated more favorable photosynthesis characteristics, less reactive oxygen species (ROS) and a greater amount of active antioxidant enzymes under the Cd condition than WT. The expression levels of the Cd uptake genes were observed to be lower in the 35S::MdIAA24 apple plants compared with those of the WT under the Cd treatment. The results highlight the ability of the overexpression of MdIAA24 to enhance apple Cd resistance by improving antioxidant capacity and reducing Cd absorption.


Assuntos
Malus , Cádmio/toxicidade , Frutas/metabolismo , Regulação da Expressão Gênica de Plantas , Humanos , Ácidos Indolacéticos , Malus/genética , Malus/metabolismo , Fotossíntese , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo
7.
Int J Mol Sci ; 22(15)2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34360850

RESUMO

Autophagy is a conserved degradation pathway for recycling damaged organelles and aberrant proteins, and its important roles in plant adaptation to nutrient starvation have been generally reported. Previous studies found that overexpression of autophagy-related (ATG) gene MdATG10 enhanced the autophagic activity in apple roots and promoted their salt tolerance. The MdATG10 expression was induced by nitrogen depletion condition in both leaves and roots of apple plants. This study aimed to investigate the differences in the growth and physiological status between wild type and MdATG10-overexpressing apple plants in response to nitrogen starvation. A hydroponic system containing different nitrogen levels was used. The study found that the reduction in growth and nitrogen concentrations in different tissues caused by nitrogen starvation was relieved by MdATG10 overexpression. Further studies demonstrated the increased root growth and the higher nitrogen absorption and assimilation ability of transgenic plants. These characteristics contributed to the increased uptake of limited nitrogen nutrients by transgenic plants, which also reduced the starvation damage to the chloroplasts. Therefore, the MdATG10-overexpressing apple plants could maintain higher photosynthetic ability and possess better growth under nitrogen starvation stress.


Assuntos
Proteínas Relacionadas à Autofagia/metabolismo , Malus/metabolismo , Nitrogênio/metabolismo , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/metabolismo , Autofagia , Cloroplastos/metabolismo , Regulação da Expressão Gênica de Plantas , Raízes de Plantas/crescimento & desenvolvimento , Estresse Fisiológico
8.
Tree Physiol ; 2021 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-34328189

RESUMO

Drought stress is an environmental factor that seriously threatens plant growth, development, and yield. VQ proteins are transcriptional regulators that have been reported to be involved in plant growth, development, and the responses to biotic and abiotic stressors. However, the relationship between VQ proteins and drought stress has not been well documented in plants. In this study, overexpressing the apple VQ motif-containing protein (MdVQ37) gene in apple plants markedly reduced the tolerance to drought. Physiological and biochemical studies further demonstrated lower enzymatic activities and decreased photosynthetic capacity in transgenic lines compared to wild-type (WT) plants under drought stress. Ultrastructural analysis of leaves showed that the leaves and palisade tissues from the transgenic lines were significantly thinner than those from WT plants. Salicylic acid (SA) analysis indicated that overexpression of MdVQ37 increased the accumulation of 2,5-DHBA by up-regulating the expression of the SA catabolic gene, which ultimately resulted to a significant reduction in endogenous SA content and the disruption of the SA-dependent signaling pathway under drought stress. Applying SA partially increased the survival rate of the transgenic lines under drought stress. These results demonstrate that the regulatory function of apple MdVQ37 is implicated in drought stress, through a change in leaf development and SA homeostasis. This study provides novel insight into understanding the multiple functions of VQ proteins.

9.
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
10.
Plant Biotechnol J ; 2021 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-34161653

RESUMO

The evolutionary history of the Malus genus has not been well studied. In the current study, we presented genetic evidence on the origin of the Malus genus based on genome sequencing of 297 Malus accessions, revealing the genetic relationship between wild species and cultivated apples. Our results demonstrated that North American and East Asian wild species are closer to the outgroup (pear) than Central Asian species, and hybrid species including natural (separated before the Pleistocene, about 2.5 Mya) and artificial hybrids (including ornamental trees and rootstocks) are between East and Central Asian wild species. Introgressions from M. sylvestris in cultivated apples appeared to be more extensive than those from M. sieversii, whose genetic background flowed westward across Eurasia and eastward to wild species including M. prunifolia, M. × asiatica, M. × micromalus, and M. × robust. Our results suggested that the loss of ancestral gene flow from M. sieversii in cultivated apples accompanied the movement of European traders around the world since the Age of Discovery. Natural SNP variations showed that cultivated apples had higher nucleotide diversity than wild species and more unique SNPs than other apple groups. An apple ERECTA-like gene that underwent selection during domestication on 15th chromosome was identified as a likely major determinant of fruit length and diameter, and an NB-ARC domain-containing gene was found to strongly affect anthocyanin accumulation using a genome-wide association approach. Our results provide new insights into the origin and domestication of apples and will be useful in new breeding programmes and efforts to increase fruit crop productivity.

11.
Int J Mol Sci ; 22(11)2021 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-34073055

RESUMO

Plant proline-rich proteins (PRPs) are cell wall proteins that occur in the plant kingdom and are involved in plant development and stress response. In this study, 9 PRP genes were identified from the apple genome and a comprehensive analysis of the PRP family was conducted, including gene structures, phylogenetic analysis, chromosome mapping, and so on. The expression of MdPRPs varied among tissues and in response to different types of stresses. MdPRP4 and MdPRP7 were induced by five detected stress treatments, including heat, drought, abscisic acid, cold, and salt; the expression patterns of the others varied under different types of stress. Subcellular localization showed that MdPRPs mainly functioned in the cytoplasm, except for MdPRP1 and MdPRP5, which also functioned in the nucleus. When MdPRP6 was overexpressed in tobacco, the transgenic plants showed higher tolerance to high temperature (48 °C) compared with wild-type (WT) plants. The transgenic plants showed milder wilting, a lower accumulation of electrolyte leakage, MDA and ROS, and a higher level of chlorophyll and SOD and POD activity, indicating that MdPRP6 may be an important gene in apples for heat stress tolerance. Overall, this study suggested that MdPRPs are critically important for the ability of apple responses to stresses.


Assuntos
Malus/genética , Proteínas de Plantas , Domínios Proteicos Ricos em Prolina , Estresse Fisiológico , Temperatura Alta , Proteínas de Plantas/genética , Proteínas de Plantas/fisiologia , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismo , Tabaco/genética , Tabaco/metabolismo
12.
BMC Genomics ; 22(1): 283, 2021 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-33874904

RESUMO

BACKGROUND: Histone lysine methylation plays an important role in plant development and stress responses by activating or repressing gene expression. Histone lysine methylation is catalyzed by a class of SET-domain group proteins (SDGs). Although an increasing number of studies have shown that SDGs play important regulatory roles in development and stress responses, the functions of SDGs in apple remain unclear. RESULTS: A total of 67 SDG members were identified in the Malus×domestica genome. Syntenic analysis revealed that most of the MdSDG duplicated gene pairs were associated with a recent genome-wide duplication event of the apple genome. These 67 MdSDG members were grouped into six classes based on sequence similarity and the findings of previous studies. The domain organization of each MdSDG class was characterized by specific patterns, which was consistent with the classification results. The tissue-specific expression patterns of MdSDGs among the 72 apple tissues in the different apple developmental stages were characterized to provide insight into their potential functions in development. The expression profiles of MdSDGs were also investigated in fruit development, the breaking of bud dormancy, and responses to abiotic and biotic stress; the results indicated that MdSDGs might play a regulatory role in development and stress responses. The subcellular localization and putative interaction network of MdSDG proteins were also analyzed. CONCLUSIONS: This work presents a fundamental comprehensive analysis of SDG histone methyltransferases in apple and provides a basis for future studies of MdSDGs involved in apple development and stress responses.


Assuntos
Malus , Regulação da Expressão Gênica de Plantas , Genoma de Planta , Histona Metiltransferases , Malus/genética , Malus/metabolismo , Família Multigênica , Filogenia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Estresse Fisiológico/genética
13.
Plant Physiol ; 185(4): 1903-1923, 2021 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-33793930

RESUMO

The R2R3 transcription factor MdMYB88 has previously been reported to function in biotic and abiotic stress responses. Here, we identify BRI1 ETHYLMETHANE SULFONATE SUPRESSOR1 (MdBES1), a vital component of brassinosteroid (BR) signaling in apple (Malus × domestica) that directly binds to the MdMYB88 promoter, regulating the expression of MdMYB88 in a dynamic and multifaceted mode. MdBES1 positively regulated expression of MdMYB88 under cold stress and pathogen attack, but negatively regulated its expression under control and drought conditions. Consistently, MdBES1 was a positive regulator for cold tolerance and disease resistance in apple, but a negative regulator for drought tolerance. In addition, MdMYB88 participated in BR biosynthesis by directly regulating the BR biosynthetic genes DE ETIOLATED 2 (MdDET2), DWARF 4 (MdDWF4), and BRASSINOSTEROID 6 OXIDASE 2 (MdBR6OX2). Applying exogenous BR partially rescued the erect leaf and dwarf phenotypes, as well as defects in stress tolerance in MdMYB88/124 RNAi plants. Moreover, knockdown of MdMYB88 in MdBES1 overexpression (OE) plants decreased resistance to a pathogen and C-REPEAT BINDING FACTOR1 expression, whereas overexpressing MdMYB88 in MdBES1 OE plants increased expression of SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 3 (MdSPL3) and BR biosynthetic genes, suggesting that MdMYB88 contributes to MdBES1 function during BR biosynthesis and the stress response. Taken together, our results reveal multifaceted regulation of MdBES1 on MdMYB88 in BR biosynthesis and stress tolerance.


Assuntos
Absorção Fisiológica/genética , Absorção Fisiológica/fisiologia , Resposta ao Choque Frio/genética , Resposta ao Choque Frio/fisiologia , Metanossulfonato de Etila/metabolismo , Malus/crescimento & desenvolvimento , Malus/genética , Produtos Agrícolas/genética , Produtos Agrícolas/crescimento & desenvolvimento , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Genes Supressores , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Fatores de Transcrição/metabolismo
14.
Plant Physiol ; 185(4): 1924-1942, 2021 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-33793944

RESUMO

Less than 40% of the nitrogen (N) fertilizer applied to soil is absorbed by crops. Thus, improving the N use efficiency of crops is critical for agricultural development. However, the underlying regulation of these processes remains largely unknown, particularly in woody plants. By conducting yeast two-hybrid assays, we identified one interacting protein of MdMYB88 and MdMYB124 in apple (Malus × domestica), namely BTB and TAZ domain protein 2 (MdBT2). Ubiquitination and protein stabilization analysis revealed that MdBT2 ubiquitinates and degrades MdMYB88 and MdMYB124 via the 26S proteasome pathway. MdBT2 negatively regulates nitrogen usage as revealed by the reduced fresh weight, dry weight, N concentration, and N usage index of MdBT2 overexpression calli under low-N conditions. In contrast, MdMYB88 and MdMYB124 increase nitrate absorption, allocation, and remobilization by regulating expression of MdNRT2.4, MdNRT1.8, MdNRT1.7, and MdNRT1.5 under N limitation, thereby regulating N usage. The results obtained illustrate the mechanism of a regulatory module comprising MdBT2-MdMYB88/MdMYB124-MdNRTs, through which plants modulate N usage. These data contribute to a molecular approach to improve the N usage of fruit crops under limited N acquisition.


Assuntos
Malus/genética , Malus/metabolismo , Nitrogênio/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Ubiquitinação/genética , Ubiquitinação/fisiologia , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Plantas Geneticamente Modificadas , Técnicas do Sistema de Duplo-Híbrido
15.
J Agric Food Chem ; 69(12): 3677-3691, 2021 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-33749265

RESUMO

The anthocyanin synthetic pathway is regulated centrally by an MYB-bHLH-WD40 (MBW) complex. Anthocyanin pigmentation is an important fruit quality trait in red-fleshed kiwifruit; however, the underlying regulatory mechanisms involving the MBW complex are not well understood. In this study, one R2R3MYB (AcMYBF110 expressed in fruit characteristically), one bHLH (AcbHLH1), two upstream regulators of AcbHLH1 (AcbHLH4 and AcbHLH5), and one WDR (AcWDR1) are characterized as being involved in the regulation of anthocyanin synthesis in kiwifruit. AcMYBF110 plays an important role in the regulation of anthocyanin accumulation by specifically activating the promoters of several anthocyanin pathway genes including AcCHS, AcF3'H, AcANS, AcUFGT3a, AcUFGT6b, and AcGST1. Coexpression of AcbHLH1, AcbHLH4, or AcbHLH5 together with AcMYBF110 induces much greater anthocyanin accumulation in both tobacco leaves and in Actinidia arguta fruit compared with AcMYBF110 alone. Moreover, this activation is further enhanced by adding AcWDR1. We found that both AcMYBF110 and AcWDR1 interact with all three AcbHLH factors, while AcMYBF110 also interacts with AcWDR1 to form three different MBW complexes that have different regulatory roles in anthocyanin accumulation of kiwifruit. The AcMYBF110-AcbHLH1-AcWDR1 complex directly targets the promoters of anthocyanin synthetic genes. Other features of the regulatory pathways identified include promotion of AcMYBF110, AcbHLH1,and AcWDR1 activities by this MBW complex, providing for both reinforcement and feedback regulation, whereas the AcMYBF110-AcbHLH4/5-AcWDR1 complex is indirectly involved in the regulation of anthocyanin synthesis by activating the promoters of AcbHLH1 and AcWDR1 to amplify the regulation signals of the first MBW complex.


Assuntos
Actinidia , Actinidia/genética , Actinidia/metabolismo , Antocianinas , Frutas/genética , Frutas/metabolismo , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo
16.
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
17.
Physiol Plant ; 172(3): 1739-1749, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33665852

RESUMO

Light regulates anthocyanins synthesis in plants. Upon exposure to visible light, the inhibition of photosynthetic electron transfer significantly lowered the contents of anthocyanins and the expression levels of key genes involved in anthocyanins synthesis in plum fruit peel. Meanwhile, the expression levels of PsmMDH2 (encoding the malate dehydrogenase in mitochondria) and PschMDH (encoding the malate dehydrogenase in chloroplasts) decreased significantly. The contents of anthocyanins and the levels of the key genes involved in anthocyanin synthesis decreased significantly with the treatment of 1-MCP (an inhibitor of ethylene perception) but were enhanced by the exogenous application of ethylene. The ethylene treatment could also recover the anthocyanin synthesis capacity lowered by the photosynthetic electron transfer inhibition. Silencing PsmMDH2 and PschMDH significantly lowered the contents of anthocyanins in plum fruit. At low temperature, visible light irradiation induced anthocyanin accumulation in Arabidopsis leaves. However, the mmdh, chmdh, and etr1-1 mutants had significantly lower anthocyanins content and expressions of the key genes involved in anthocyanins synthesis compared to wild type. Overall, the present study demonstrates that both photosynthesis and respiration were involved in the regulation of anthocyanin synthesis in visible light. The visible light regulates anthocyanin synthesis by controlling the malate metabolism via MDHs and the ethylene signaling pathway.


Assuntos
Prunus domestica , Antocianinas , Etilenos , Frutas/genética , Regulação da Expressão Gênica de Plantas , Luz , Malato Desidrogenase/genética , Malatos , Transdução de Sinais
18.
BMC Plant Biol ; 21(1): 81, 2021 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-33557757

RESUMO

BACKGROUND: Calcium (Ca2+) plays an important role in plant growth and development, and the maintenance of calcium homeostasis is necessary for the survival of all plant species. Ca2+/H+ exchangers (CAXs) are a subgroup of the CaCA (Ca2+/cation antiporter) superfamily. In general, CAX proteins mediate cytosolic Ca2+ entry into vacuoles to prevent excessive accumulation of Ca2+ in the cytosol. The CaCA superfamily has been identified and characterised in many plant species; however, characterisation of the CaCA superfamily and functional study of apple CAX proteins have yet to be conducted in apple (Malus × domestica Borkh.). RESULTS: Here, we identified 21 CaCA family proteins in apple for the first time. Phylogenetic and gene structure analysis, as well as prediction of conserved motifs, suggested that these proteins could be classified into four groups: CAX, CCX, NCL, and MHX. Expression analysis showed that the 10 MdCAX genes we cloned strongly responded to calcium and abiotic stress treatments. Collinearity analysis and characterisation of calcium transport capacity resulted in the identification of a pair of segmental duplication genes: MdCAX3L-1 and MdCAX3L-2; MdCAX3L-2 showed strong calcium transport capacity, whereas MdCAX3L-1 showed no calcium transport capacity. Yeast two-hybrid (Y2H) assays showed that these two proteins could interact with each other. The high sequence similarity (94.6%) makes them a good model for studying the crucial residues and structural basis of the calcium transport of CAX proteins. Prediction of the protein interaction network revealed several proteins that may interact with CAX proteins and play important roles in plant stress responses, such as SOS2, CXIP1, MHX, NRAMP3, and MTP8. CONCLUSIONS: Our analysis indicated that MdCAX proteins have strong calcium transport capacity and are involved in the abiotic stress response in apple. These findings provide new insight and rich resources for future studies of MdCAX proteins in apple.


Assuntos
Cálcio/metabolismo , Transporte de Íons/genética , Malus/genética , Malus/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Estresse Fisiológico/genética , Regulação da Expressão Gênica de Plantas , Genoma de Planta , Estudo de Associação Genômica Ampla , Família Multigênica
19.
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
20.
Proc Natl Acad Sci U S A ; 118(1)2021 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-33443220

RESUMO

Sugar transport across tonoplasts is essential for maintaining cellular sugar homeostasis and metabolic balance in plant cells. It remains unclear, however, how this process is regulated among different classes of sugar transporters. Here, we identified a tonoplast H+/glucose symporter, MdERDL6-1, from apples, which was highly expressed in fruits and exhibited expression patterns similar to those of the tonoplast H+/sugar antiporters MdTST1 and MdTST2. Overexpression of MdERDL6-1 unexpectedly increased not only glucose (Glc) concentration but also that of fructose (Fru) and sucrose (Suc) in transgenic apple and tomato leaves and fruits. RNA sequencing (RNA-seq) and expression analyses showed an up-regulation of TST1 and TST2 in the transgenic apple and tomato lines overexpressing MdERDL6-1 Further studies established that the increased sugar concentration in the transgenic lines correlated with up-regulation of TST1 and TST2 expression. Suppression or knockout of SlTST1 and SlTST2 in the MdERDL6-1-overexpressed tomato background reduced or abolished the positive effect of MdERDL6-1 on sugar accumulation, respectively. The findings demonstrate a regulation of TST1 and TST2 by MdERDL6-1, in which Glc exported by MdERDL6-1 from vacuole up-regulates TST1 and TST2 to import sugars from cytosol to vacuole for accumulation to high concentrations. The results provide insight into the regulatory mechanism of sugar accumulation in vacuoles mediated by the coordinated action of two classes of tonoplast sugar transporters.


Assuntos
Regulação da Expressão Gênica de Plantas/genética , Lycopersicon esculentum/metabolismo , Malus/metabolismo , Proteínas de Transporte de Monossacarídeos/metabolismo , Proteínas de Plantas/metabolismo , Vacúolos/metabolismo , Citosol/metabolismo , Frutose/metabolismo , Frutas/metabolismo , Técnicas de Inativação de Genes , Inativação Gênica , Glucose/metabolismo , Lycopersicon esculentum/genética , Malus/genética , Proteínas de Transporte de Monossacarídeos/genética , Filogenia , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas , Regiões Promotoras Genéticas , RNA-Seq , Sacarose/metabolismo , Regulação para Cima
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