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1.
Nat Commun ; 11(1): 4058, 2020 08 13.
Artigo em Inglês | MEDLINE | ID: mdl-32792480

RESUMO

Tomatoes come in a multitude of shapes and flavors despite a narrow genetic pool. Here, we leverage whole-genome resequencing data available for 602 cultivated and wild accessions to determine the contribution of transposable elements (TEs) to tomato diversity. We identify 6,906 TE insertions polymorphisms (TIPs), which result from the mobilization of 337 distinct TE families. Most TIPs are low frequency variants and TIPs are disproportionately located within or adjacent to genes involved in environmental responses. In addition, genic TE insertions tend to have strong transcriptional effects and they can notably lead to the generation of multiple transcript isoforms. Using genome-wide association studies (GWAS), we identify at least 40 TIPs robustly associated with extreme variation in major agronomic traits or secondary metabolites and in most cases, no SNP tags the TE insertion allele. Collectively, these findings highlight the unique role of TE mobilization in tomato diversification, with important implications for breeding.


Assuntos
Elementos de DNA Transponíveis/genética , Lycopersicon esculentum/genética , Evolução Molecular , Genoma de Planta/genética , Estudo de Associação Genômica Ampla , Polimorfismo Genético/genética
2.
Proc Natl Acad Sci U S A ; 117(29): 17409-17417, 2020 07 21.
Artigo em Inglês | MEDLINE | ID: mdl-32616567

RESUMO

Proteolytic cascades regulate immunity and development in animals, but these cascades in plants have not yet been reported. Here we report that the extracellular immune protease Rcr3 of tomato is activated by P69B and other subtilases (SBTs), revealing a proteolytic cascade regulating extracellular immunity in solanaceous plants. Rcr3 is a secreted papain-like Cys protease (PLCP) of tomato that acts both in basal resistance against late blight disease (Phytophthora infestans) and in gene-for-gene resistance against the fungal pathogen Cladosporium fulvum (syn. Passalora fulva) Despite the prevalent model that Rcr3-like proteases can activate themselves at low pH, we found that catalytically inactive proRcr3 mutant precursors are still processed into mature mRcr3 isoforms. ProRcr3 is processed by secreted P69B and other Asp-selective SBTs in solanaceous plants, providing robust immunity through SBT redundancy. The apoplastic effector EPI1 of P. infestans can block Rcr3 activation by inhibiting SBTs, suggesting that this effector promotes virulence indirectly by preventing the activation of Rcr3(-like) immune proteases. Rcr3 activation in Nicotiana benthamiana requires a SBT from a different subfamily, indicating that extracellular proteolytic cascades have evolved convergently in solanaceous plants or are very ancient in the plant kingdom. The frequent incidence of Asp residues in the cleavage region of Rcr3-like proteases in solanaceous plants indicates that activation of immune proteases by SBTs is a general mechanism, illuminating a proteolytic cascade that provides robust apoplastic immunity.


Assuntos
Lycopersicon esculentum/metabolismo , Peptídeo Hidrolases/metabolismo , Doenças das Plantas/imunologia , Imunidade Vegetal , Proteólise , Cladosporium , Lycopersicon esculentum/genética , Peptídeo Hidrolases/genética , Phytophthora infestans , Doenças das Plantas/parasitologia , Doenças das Plantas/prevenção & controle , Proteínas de Plantas/metabolismo , Isoformas de Proteínas , Virulência
3.
Gene ; 759: 145002, 2020 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-32726608

RESUMO

Recent evidence has shown that microRNAs are transferred from one species to another through cross-species transmission and exhibit biological activities in the receptor. However, the cross-kingdom regulation of pathogen virulence by plant-derived miRNAs is rarely reported. This study investigated the regulatory role of novel tomato miRNA miR1001 in the growth and development of Botrytis cinerea. Results showed that miR1001 inhibited the virulence of B. cinerea-infected plants, and the inhibitory effect of miR1001/miR1001* was stronger than that of miR1001. Moreover, miR1001 exerted a significant inhibitory effect on the conidiospore germination of B. cinerea. Degradome-seq experiment showed that miR1001 can directly target the Bcin03g02170.1 and Bcin10g01400.1 genes, which respectively encode the ATP-dependent metallopeptidase and cysteine-type endopeptidase, in B. cinerea. The interactions of both targets with miR1001 were further confirmed by using transient co-expression in tobacco. Real-time RT-PCR analysis showed that the expression levels of the two target genes were significantly downregulated in B. cinerea with miR1001 treatment. Our findings provide new evidence into the coevolution of pathogens and host plants, as well as new directions for the use of plant-derived miRNAs to control pathogens.


Assuntos
Botrytis/patogenicidade , Proteínas Fúngicas/genética , Interações Hospedeiro-Patógeno , Lycopersicon esculentum/genética , MicroRNAs/metabolismo , RNA de Plantas/metabolismo , Botrytis/fisiologia , Proteínas Fúngicas/metabolismo , Lycopersicon esculentum/microbiologia , MicroRNAs/genética , RNA de Plantas/genética , Esporos Fúngicos/fisiologia
4.
PLoS One ; 15(7): e0222747, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32639982

RESUMO

Physiology-based differentiation of SH genes and Hemileia vastatrix races is the principal method employed for the characterization of coffee leaf rust resistance. Based on the gene-for-gene theory, nine major rust resistance genes (SH1-9) have been proposed. However, these genes have not been characterized at the molecular level. Consequently, the lack of molecular data regarding rust resistance genes or candidates is a major bottleneck in coffee breeding. To address this issue, we screened a BAC library with resistance gene analogs (RGAs), identified RGAs, characterized and explored for any SH related candidate genes. Herein, we report the identification and characterization of a gene (gene 11), which shares conserved sequences with other SH genes and displays a characteristic polymorphic allele conferring different resistance phenotypes. Furthermore, comparative analysis of the two RGAs belonging to CC-NBS-LRR revealed more intense diversifying selection in tomato and grape genomes than in coffee. For the first time, the present study has unveiled novel insights into the molecular nature of the SH genes, thereby opening new avenues for coffee rust resistance molecular breeding. The characterized candidate RGA is of particular importance for further biological function analysis in coffee.


Assuntos
Café/genética , Resistência à Doença/genética , Genoma de Planta , Sequência de Aminoácidos , Basidiomycota/fisiologia , Sítios de Ligação , Café/classificação , Biblioteca Gênica , Lycopersicon esculentum/classificação , Lycopersicon esculentum/genética , Fases de Leitura Aberta/genética , Filogenia , Doenças das Plantas/microbiologia , Proteínas de Plantas/química , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Polimorfismo Genético , Alinhamento de Sequência , Fatores de Virulência/genética , Fatores de Virulência/metabolismo , Vitis/classificação , Vitis/genética
5.
PLoS One ; 15(6): e0234011, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32484825

RESUMO

The tomato AGC protein kinase Adi3 is a Ser/Thr kinase that functions as a negative regulator of programmed cell death through cell death suppression (CDS) activity in the nucleus. In this study, to understand the mechanism of Adi3 CDS, peptide microarrays containing random Ser- and Thr-peptide phosphorylation substrates were used to screen for downstream phosphorylation substrates. In the microarray phosphorylation assay, Adi3 showed promiscuous kinase activity more toward Ser-peptides compared to Thr-peptides, and a preference for aromatic and cyclic amino acids on both Ser- and Thr-peptides was seen. The 63 highest phosphorylated peptide sequences from the Ser-peptide microarray were selected as queries for a BLAST search against the tomato proteome. As a result, 294 candidate nuclear Adi3 substrates were selected and categorized based on their functions. Many of these proteins were classified as DNA/RNA polymerases or regulators involved in transcription and translation events. The list of potential Adi3 substrates was narrowed to eleven and four candidates were tested for phosphorylation by Adi3. Two of these candidates, RNA polymerase II 2nd largest subunit (RPB2) and the pathogen defense related transcription factor Pti5, were confirmed as Adi3 phosphorylation substrates by in vitro kinase assays. Using a mutational approach two residues, Thr675 and Thr676, were identified as Adi3 phosphorylation sites on RPB2. This study provides the foundation for understanding Adi3 CDS mechanisms in the nucleus as well as other cellular functions.


Assuntos
Morte Celular/genética , Peptídeos/genética , Células Vegetais/metabolismo , Proteínas de Plantas/genética , Sequência de Aminoácidos , Núcleo Celular/genética , Lycopersicon esculentum/genética , Lycopersicon esculentum/metabolismo , Análise em Microsséries , Mutação/genética , Fosforilação/genética , Proteínas Quinases/genética
7.
Proc Natl Acad Sci U S A ; 117(24): 13800-13809, 2020 06 16.
Artigo em Inglês | MEDLINE | ID: mdl-32493747

RESUMO

While colocalization within a bacterial operon enables coexpression of the constituent genes, the mechanistic logic of clustering of nonhomologous monocistronic genes in eukaryotes is not immediately obvious. Biosynthetic gene clusters that encode pathways for specialized metabolites are an exception to the classical eukaryote rule of random gene location and provide paradigmatic exemplars with which to understand eukaryotic cluster dynamics and regulation. Here, using 3C, Hi-C, and Capture Hi-C (CHi-C) organ-specific chromosome conformation capture techniques along with high-resolution microscopy, we investigate how chromosome topology relates to transcriptional activity of clustered biosynthetic pathway genes in Arabidopsis thaliana Our analyses reveal that biosynthetic gene clusters are embedded in local hot spots of 3D contacts that segregate cluster regions from the surrounding chromosome environment. The spatial conformation of these cluster-associated domains differs between transcriptionally active and silenced clusters. We further show that silenced clusters associate with heterochromatic chromosomal domains toward the periphery of the nucleus, while transcriptionally active clusters relocate away from the nuclear periphery. Examination of chromosome structure at unrelated clusters in maize, rice, and tomato indicates that integration of clustered pathway genes into distinct topological domains is a common feature in plant genomes. Our results shed light on the potential mechanisms that constrain coexpression within clusters of nonhomologous eukaryotic genes and suggest that gene clustering in the one-dimensional chromosome is accompanied by compartmentalization of the 3D chromosome.


Assuntos
Arabidopsis/genética , Cromossomos de Plantas/genética , Lycopersicon esculentum/genética , Família Multigênica , Proteínas de Plantas/genética , Zea mays/genética , Arabidopsis/metabolismo , Cromossomos de Plantas/metabolismo , Genoma de Planta , Lycopersicon esculentum/metabolismo , Oryza/genética , Oryza/metabolismo , Proteínas de Plantas/metabolismo , Zea mays/metabolismo
8.
Physiol Plant ; 170(2): 202-217, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32458443

RESUMO

Ethylene is considered one of the most important plant hormones orchestrating plant responses to flooding stress. However, ethylene may induce deleterious effects on plants, especially when produced at high rates in response to stress. In this paper, we explored the effect of attenuated ethylene sensitivity in the Never ripe (Nr) mutant on leaf photosynthetic capacity of flooded tomato plants. We found out that reduced ethylene perception in Nr plants was associated with a more efficient photochemical and non-photochemical radiative energy dissipation capability in response to flooding. The data correlated with the retention of chlorophyll and carotenoids content in flooded Nr leaves. Moreover, leaf area and specific leaf area were higher in Nr, indicating that ethylene would exert a negative role in leaf growth and expansion under flooded conditions. Although stomatal conductance was hampered in flooded Nr plants, carboxylation activity was not affected by flooding in the mutant, suggesting that ethylene is responsible for inducing non-stomatal limitations to photosynthetic CO2 uptake. Upregulation of several cysteine protease genes and high protease activity led to Rubisco protein loss in response to ethylene under flooding. Reduction of Rubisco content would, at least in part, account for the reduction of its carboxylation efficiency in response to ethylene in flooded plants. Therefore, besides its role as a trigger of many adaptive responses, perception of ethylene entails limitations in light and dark photosynthetic reactions by speeding up the senescence process that leads to a progressive disassembly of the photosynthetic machinery in leaves of flooded tomato plants.


Assuntos
Lycopersicon esculentum/genética , Clorofila , Etilenos , Inundações , Fotossíntese , Folhas de Planta
9.
Ann Bot ; 126(2): 315-322, 2020 07 24.
Artigo em Inglês | MEDLINE | ID: mdl-32407462

RESUMO

BACKGROUND AND AIMS: Dutch tomato cultivars tend to have a greater yield than Japanese cultivars even if they are grown under the same conditions. Factors contributing to the increased yield of the Dutch cultivars were a greater light use efficiency and greater leaf photosynthetic rate. On the other hand, the relationship between tomato yields and anatomical traits is still unclear. The aim of this study is to identify the anatomical traits related to the difference in yield between Dutch and Japanese cultivars. METHODS: Anatomical properties were compared during different growth stages of Dutch and Japanese tomatoes. Hormone profiles and related gene expression in hypocotyls of Dutch and Japanese cultivars were compared in the hypocotyls of 3- and 4-week-old plants. KEY RESULTS: Dutch cultivars have a more developed secondary xylem than Japanese cultivars, which would allow for greater transport of water, mineral nutrients and phytohormones to the shoots. The areas and ratios of the xylem in the hypocotyls of 3- to 6-week-old plants were larger in the Dutch cultivars. In reciprocal grafts of the Japanese and Dutch cultivars, xylem development at the scion and rootstock depended on the scion cultivar, suggesting that some factors in the scion are responsible for the difference in xylem development. The cytokinin content, especially the level of N6-(Δ 2-isopentenyl) adenine (iP)-type cytokinin, was higher in the Dutch cultivars. This result was supported by the greater expression of Sl-IPT3 (a cytokinin biosynthesis gene) and Sl-RR16/17 (a cytokinin-responsive gene) in the Dutch cultivars. CONCLUSIONS: These results suggest that iP-type cytokinins, which are locally synthesized in the hypocotyl, contribute to xylem development. The greater xylem development in Dutch cultivars might contribute to the high yield of the tomato.


Assuntos
Lycopersicon esculentum/genética , Citocininas , Hipocótilo/genética , Japão , Xilema
10.
Physiol Plant ; 170(1): 120-131, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32356387

RESUMO

To examine the physiological role of hexose transporters in determining the sink strength of individual fruits, the regulation of hexose transporters gene expression was studied when the sink/source ratio was artificially altered under the greenhouse condition; this was done in two cultivars of tomato, i.e. Grandella and Isabella. The sink/source ratio treatments included: saving one fruit per truss (1F), two fruits per truss (2F), three fruits per truss (3F) and no fruit pruning (control). The results showed that fruit thinning could increase starch, sucrose, and hexose contents in the fruits; it could also modulate the activity of the key enzymes and the expression of tomato hexose transporter genes (LeHTs). Based on the relative transcript levels, all examined LeHTs were unregulated at the end of cell division and the cell expansion stage of fruit development, but the strongest expression level observed at the onset of ripening was related to LeHT1 and LeHT2. Given the concomitancy of cell wall invertase (EC 3.2.1.26) activity and the LeHTs relative expression cell wall, invertase activity seemed to be involved in the expression level of LeHTs. The increased trends of the LeHTs expression with the decrease of the sink/source ratio confirmed the role of hexose transporters in determining the sink strength of the tomato fruits.


Assuntos
Lycopersicon esculentum/genética , Frutas/genética , Hexoses , Proteínas de Transporte de Monossacarídeos/genética , beta-Frutofuranosidase
11.
Ecotoxicol Environ Saf ; 200: 110720, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32470680

RESUMO

Acid rain is a widespread environmental issue intensely affecting normal plant growth of crops. Melatonin is well known pleiotropic molecule which improves abiotic and biotic stress tolerance of plants through physiological and molecular mediation. However, the impact of exogenous melatonin on molecular activities under acid rain conditions in plants has never been studied. The objective of the study is to expose the possible role of exogenous melatonin on physiological and molecular changes against acid rain stress in tomato. Transcriptome profile through RNA-sequence analysis identified 1228, 1120 and 1537 differentially expressed genes (DEGs) in control plant (Ctr) vs simulated acid rain stressed plant (P25) comparison, control plant vs melatonin treatment in simulated acid rain stressed plant (P25M) comparison and P25 vs P25M comparison, respectively. Among them, 152 differentially expressed genes (DEGs) were commonly expressed and the expression of secondary metabolites related gene was noticeably observed in all comparison. Moreover, transcript families such as ERF, WRKY, MYB and bZIP related gene accounted more in all treatment comparison. The RNA-sequence and qPCR results indicated that exogenous melatonin is closely associated with acid rain stress moderator and might be involved in alteration of differentially expressed genes (DEGs), biosynthesis of plant secondary metabolites and transcriptional factor encoding genes expression which might have potential application against environmental hazardous conditions.


Assuntos
Chuva Ácida/efeitos adversos , Lycopersicon esculentum/efeitos dos fármacos , Melatonina/farmacologia , Fatores de Transcrição/metabolismo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Lycopersicon esculentum/genética , Lycopersicon esculentum/metabolismo , Metabolismo Secundário/efeitos dos fármacos , Metabolismo Secundário/genética , Análise de Sequência de RNA , Estresse Fisiológico , Fatores de Transcrição/genética , Transcriptoma/efeitos dos fármacos
12.
Gene ; 746: 144652, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32259631

RESUMO

Circular RNAs (circRNAs), a novel branch of noncoding RNAs, are widespread in eukaryotic cells. Particularly, due to their abilities to bind microRNA (miRNA) and serve as "sponges", circRNAs can regulate gene expression and participate in multiple biological processes. To detect the function of the circRNAs in tomato resistance, in our study, high-throughput sequencing were used to detect the circRNAs in tomatoes before and after Phytophthora infestans (P. infestans) infection. A total of 68 circRNAs were identified, of them, 18 (26%) were termed as exonic circRNAs, 33 (49%) were termed as intergenic circRNAs, 17 (25%) were termed as intronic circRNAs. Thirty-six out of 68 circRNAs differentially expressed in tomatoes after infection, including 9 up- and 27 down-regulated. Among the up-regulated circRNAs, two exoinc circRNAs, circRNA45 and circRNA47 were annotated as whitefly-induced gp91-phox and ethylene-forming enzyme, respectively. Both of them could act as miR477-3p sponge. Transgenic plants transiently overexpressed circRNA45 and circRNA47 both displayed smaller lesion area than the control plants upon infection, accompanied by lower expression levels of miR477-3p. Furthermore, transiently overexpression of miR477-3p in tomatoes leading to a decline in their targeted disease related genes expression. Our results firstly identified circRNAs in tomato upon P. infestans infection and demonstrated that circRNA45 and circRNA47 may act as positive regulators in tomato resistance by regulating miRNA-mRNAs expression levels.


Assuntos
Resistência à Doença/genética , Regulação da Expressão Gênica de Plantas , Lycopersicon esculentum , Phytophthora infestans , Doenças das Plantas , RNA Circular , RNA de Plantas , Lycopersicon esculentum/genética , Lycopersicon esculentum/metabolismo , Lycopersicon esculentum/microbiologia , MicroRNAs/biossíntese , MicroRNAs/genética , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , RNA Circular/biossíntese , RNA Circular/genética , RNA de Plantas/biossíntese , RNA de Plantas/genética
13.
Nat Genet ; 52(5): 534-540, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32284578

RESUMO

Structural variants and presence/absence polymorphisms are common in plant genomes, yet they are routinely overlooked in genome-wide association studies (GWAS). Here, we expand the type of genetic variants detected in GWAS to include major deletions, insertions and rearrangements. We first use raw sequencing data directly to derive short sequences, k-mers, that mark a broad range of polymorphisms independently of a reference genome. We then link k-mers associated with phenotypes to specific genomic regions. Using this approach, we reanalyzed 2,000 traits in Arabidopsis thaliana, tomato and maize populations. Associations identified with k-mers recapitulate those found with SNPs, but with stronger statistical support. Importantly, we discovered new associations with structural variants and with regions missing from reference genomes. Our results demonstrate the power of performing GWAS before linking sequence reads to specific genomic regions, which allows the detection of a wider range of genetic variants responsible for phenotypic variation.


Assuntos
Genoma de Planta/genética , Polimorfismo de Nucleotídeo Único/genética , Variação Biológica da População , Estudo de Associação Genômica Ampla/métodos , Genômica/métodos , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Lycopersicon esculentum/genética , Fenótipo , Análise de Sequência de DNA/métodos , Zea mays/genética
14.
J Vis Exp ; (157)2020 03 10.
Artigo em Inglês | MEDLINE | ID: mdl-32225144

RESUMO

Tomato is an agronomically important crop that can be infected by Pseudomonas syringae, a Gram-negative bacterium, resulting in bacterial speck disease. The tomato-P. syringae pv. tomato pathosystem is widely used to dissect the genetic basis of plant innate responses and disease resistance. While disease was successfully managed for many decades through the introduction of the Pto/Prf gene cluster from Solanum pimpinellifolium into cultivated tomato, race 1 strains of P. syringae have evolved to overcome resistance conferred by the Pto/Prf gene cluster and occur worldwide. Wild tomato species are important reservoirs of natural diversity in pathogen recognition, because they evolved in diverse environments with different pathogen pressures. In typical screens for disease resistance in wild tomato, adult plants are used, which can limit the number of plants that can be screened due to their extended growth time and greater growth space requirements. We developed a method to screen 10-day-old tomato seedlings for resistance, which minimizes plant growth time and growth chamber space, allows a rapid turnover of plants, and allows large sample sizes to be tested. Seedling outcomes of survival or death can be treated as discrete phenotypes or on a resistance scale defined by amount of new growth in surviving seedlings after flooding. This method has been optimized to screen 10-day-old tomato seedlings for resistance to two P. syringae strains and can easily be adapted to other P. syringae strains.


Assuntos
Bioensaio/métodos , Resistência à Doença , Lycopersicon esculentum/microbiologia , Doenças das Plantas/microbiologia , Pseudomonas syringae/fisiologia , Plântula/microbiologia , Cotilédone/fisiologia , Meios de Cultura , Ecótipo , Lycopersicon esculentum/genética , Lycopersicon esculentum/crescimento & desenvolvimento , Fenótipo , Esterilização
15.
J Vis Exp ; (157)2020 03 11.
Artigo em Inglês | MEDLINE | ID: mdl-32225152

RESUMO

Ralstonia solanacearum is a devastating soil borne vascular pathogen that can infect a large range of plant species, causing an important threat to agriculture. However, the Ralstonia model is considerably underexplored in comparison to other models involving bacterial plant pathogens, such as Pseudomonas syringae in Arabidopsis. Research targeted to understanding the interaction between Ralstonia and crop plants is essential to develop sustainable solutions to fight against bacterial wilt disease but is currently hindered by the lack of straightforward experimental assays to characterize the different components of the interaction in native host plants. In this scenario, we have developed a method to perform genetic analysis of Ralstonia infection of tomato, a natural host of Ralstonia. This method is based on Agrobacterium rhizogenes-mediated transformation of tomato roots, followed by Ralstonia soil-drenching inoculation of the resulting plants, containing transformed roots expressing the construct of interest. The versatility of the root transformation assay allows performing either gene overexpression or gene silencing mediated by RNAi. As a proof of concept, we used this method to show that RNAi-mediated silencing of SlCESA6 in tomato roots conferred resistance to Ralstonia. Here, we describe this method in detail, enabling genetic approaches to understand bacterial wilt disease in a relatively short time and with small requirements of equipment and plant growth space.


Assuntos
Lycopersicon esculentum/genética , Lycopersicon esculentum/microbiologia , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Raízes de Plantas/microbiologia , Ralstonia solanacearum/fisiologia , Transformação Genética , Agrobacterium/metabolismo , Antibacterianos/farmacologia , Arabidopsis/microbiologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Inativação Gênica/efeitos dos fármacos , Lycopersicon esculentum/efeitos dos fármacos , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/genética , Ralstonia solanacearum/efeitos dos fármacos , Ralstonia solanacearum/crescimento & desenvolvimento , Reprodutibilidade dos Testes , Solo , Transformação Genética/efeitos dos fármacos
16.
Nat Commun ; 11(1): 1221, 2020 03 06.
Artigo em Inglês | MEDLINE | ID: mdl-32144266

RESUMO

Silencing of transposable elements (TEs) is established by small RNA-directed DNA methylation (RdDM). Maintenance of silencing is then based on a combination of RdDM and RNA-independent mechanisms involving DNA methyltransferase MET1 and chromodomain DNA methyltransferases (CMTs). Involvement of RdDM, according to this model should decrease with TE age but here we show a different pattern in tomato and Arabidopsis. In these species the CMTs silence long terminal repeat (LTR) transposons in the distal chromatin that are younger than those affected by RdDM. To account for these findings we propose that, after establishment of primary RdDM as in the original model, there is an RNA-independent maintenance phase involving CMTs followed by secondary RdDM. This progression of epigenetic silencing in the gene-rich distal chromatin is likely to influence the transcriptome either in cis or in trans depending on whether the mechanisms are RNA-dependent or -independent.


Assuntos
Metilação de DNA/genética , Elementos de DNA Transponíveis/genética , Nucleotídeos/genética , Sistemas CRISPR-Cas/genética , Cromatina/metabolismo , Evolução Molecular , Inativação Gênica , Lycopersicon esculentum/genética , Lycopersicon esculentum/crescimento & desenvolvimento , Mutação/genética , Fenótipo , Proteínas de Plantas/metabolismo , RNA Polimerase II/metabolismo , Sequências Repetidas Terminais/genética
17.
Artigo em Inglês | MEDLINE | ID: mdl-32005380

RESUMO

The soil-born vascular disease Verticillium wilt, which is caused by fungal pathogen Verticillium dahliae, is a devastating disease of cotton worldwide. In the last decade, a large number of genes have been found to participate in cotton-V. dahliae interactions, but the detailed mechanisms of cotton resistance to V. dahliae remain unclear. Here, we functionally characterized MPK3, a MAPK gene from cotton. MPK3 was induced in the roots of both resistant and susceptible cotton cultivars by V. dahliae inoculation. Transgenic cotton and tobacco with constitutively higher GbMPK3 expression conferred higher V. dahliae susceptibility, while MPK3 knockdown in cotton has limited effect on cotton resistance to V. dahliae. Expression profiling revealed that SA-mediated defense pathway genes (WRKY70, PR1, and PR5) accumulated after V. dahliae inoculation in roots of both wild-type and transgenic cotton, and the expression levels of these genes were higher in GbMPK3-overexpressing plants than in wild-type plants, indicating that GbMPK3 upregulation may reduce plant resistance to V. dahliae through regulating salicylic acid signaling transduction.


Assuntos
Resistência à Doença/genética , Regulação da Expressão Gênica de Plantas , Gossypium/genética , Ácido Salicílico/metabolismo , Transdução de Sinais , Verticillium/fisiologia , Gossypium/metabolismo , Gossypium/microbiologia , Lycopersicon esculentum/genética , Lycopersicon esculentum/metabolismo , Lycopersicon esculentum/microbiologia , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismo , Plantas Geneticamente Modificadas/microbiologia
18.
Artigo em Inglês | MEDLINE | ID: mdl-32005392

RESUMO

The cyclic electron flow (CEF) around photosystem I (PSI) plays a crucial role in photosynthesis and also functions in plant tolerance of abiotic environmental stress. However, the role of PGR5/PGRL1- and NDH-dependent CEF in tomato under hightemperature (HT) is poorly understood. Here, we assessed the photoprotective effect of these pathways in tomato leaves under HT by using antimycin A (AA) and rotenone (R), which are chemical inhibitors of PGR5/PGRL1- and NDH-dependent CEF, respectively. The results showed that AA treatment caused significantly greater inhibition of CEF under HT compared to R treatment. Moreover, AA treatment caused a greater decrease in maximal photochemistry efficiency (Fv/Fm) and increased damage to the donor and acceptor side of photosystem II (PSII); however, the limitation of the acceptor side in PSI [Y(NA)] was significantly increased. In addition, thylakoid membrane integrity was compromised and reactive oxygen species, proton gradient (ΔpH), antioxidant enzyme activity, and the expression of photosystem core subunit genes were significantly decreased under AA treatment. These findings indicate that PGR5/PGRL1-dependent CEF protects PSII and PSI from photooxidative damage through the formation of ΔpH while maintaining thylakoid membrane integrity and normal gene expression levels of core photosystem components. This study demonstrates that PGR5/PGRL1-dependent CEF plays a major role in HT response in tomato.


Assuntos
Elétrons , Temperatura Alta , Lycopersicon esculentum/genética , Proteínas de Plantas/genética , Espécies Reativas de Oxigênio/metabolismo , Complexos de ATP Sintetase/genética , Complexos de ATP Sintetase/metabolismo , Expressão Gênica , Lycopersicon esculentum/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , NADPH Desidrogenase/genética , NADPH Desidrogenase/metabolismo , Complexo de Proteínas do Centro de Reação Fotossintética/genética , Complexo de Proteínas do Centro de Reação Fotossintética/metabolismo , Complexo de Proteína do Fotossistema I/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , Força Próton-Motriz
19.
PLoS One ; 15(2): e0229215, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32101558

RESUMO

We hypothesize that by simulating the natural priming in seeds of a species that forms transient seed banks it is possible to clarify molecular aspects of germination that lead to the recruitment of seedlings when the next rainy season begins. We used seeds of Solanum lycocarpum as a biological model. Our findings support the idea that the increment of seed germination kinetics when the rainy season returns is mainly based on the metabolism and embryonic growth, and that the hydropriming, at the end of seed dispersion, increases the germination window time of these seeds by mainly increasing the degradation of galactomannan of the cell wall. This can improve the energy supply (based on carbon metabolism) for seedling growth in post-germination, which improves the seedling's survival chances. From these findings, we promote a hypothetical model about how the priming at the end of the rainy season acts on mRNA synthesis in the germination of seeds from transient banks and the consequence of this priming at the beginning of the following rainy season. This model predicts that besides the Gibberellin and Abscisic Acid balance (content and sensitivity), Auxin would be a key component for the seed-seedling transition in Neotropical areas. Seed collection was performed under authorization number SISGEN AB0EB45.


Assuntos
Regulação da Expressão Gênica no Desenvolvimento , Germinação , Lycopersicon esculentum/crescimento & desenvolvimento , Modelos Teóricos , Chuva , Banco de Sementes , Sementes/crescimento & desenvolvimento , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Lycopersicon esculentum/genética , Lycopersicon esculentum/metabolismo , Dispersão de Sementes , Sementes/genética , Sementes/metabolismo , Transdução de Sinais
20.
Proc Natl Acad Sci U S A ; 117(4): 2211-2217, 2020 01 28.
Artigo em Inglês | MEDLINE | ID: mdl-31964814

RESUMO

As global climate change brings elevated average temperatures and more frequent and extreme weather events, pressure from biotic stresses will become increasingly compounded by harsh abiotic stress conditions. The plant hormone jasmonate (JA) promotes resilience to many environmental stresses, including attack by arthropod herbivores whose feeding activity is often stimulated by rising temperatures. How wound-induced JA signaling affects plant adaptive responses to elevated temperature (ET), however, remains largely unknown. In this study, we used the commercially important crop plant Solanum lycopersicum (cultivated tomato) to investigate the interaction between simulated heat waves and wound-inducible JA responses. We provide evidence that the heat shock protein HSP90 enhances wound responses at ET by increasing the accumulation of the JA receptor, COI1. Wound-induced JA responses directly interfered with short-term adaptation to ET by blocking leaf hyponasty and evaporative cooling. Specifically, leaf damage inflicted by insect herbivory or mechanical wounding at ET resulted in COI1-dependent stomatal closure, leading to increased leaf temperature, lower photosynthetic carbon assimilation rate, and growth inhibition. Pharmacological inhibition of HSP90 reversed these effects to recapitulate the phenotype of a JA-insensitive mutant lacking the COI1 receptor. As climate change is predicted to compound biotic stress with larger and more voracious arthropod pest populations, our results suggest that antagonistic responses resulting from a combination of insect herbivory and moderate heat stress may exacerbate crop losses.


Assuntos
Insetos/fisiologia , Lycopersicon esculentum/química , Folhas de Planta/parasitologia , Animais , Mudança Climática , Ciclopentanos/metabolismo , Comportamento Alimentar , Proteínas de Choque Térmico HSP90/genética , Proteínas de Choque Térmico HSP90/metabolismo , Herbivoria/fisiologia , Temperatura Alta , Lycopersicon esculentum/genética , Lycopersicon esculentum/metabolismo , Lycopersicon esculentum/parasitologia , Oxilipinas/metabolismo , Reguladores de Crescimento de Planta/metabolismo , Folhas de Planta/química , Folhas de Planta/genética , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo
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