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1.
Small ; : e2402863, 2024 May 19.
Artículo en Inglés | MEDLINE | ID: mdl-38764314

RESUMEN

Facing the increasing global shortage of freshwater resources, this study presents a suspended multilayer evaporator (SMLE), designed to tackle the principal issues plaguing current solar-driven interfacial evaporation technologies, specifically, substantial thermal losses and limited water production. This approach, through the implementation of a multilayer structural design, enables superior thermal regulation throughout the evaporation process. This evaporator consists of a radiation damping layer, a photothermal conversion layer, and a bottom layer that leverages radiation, wherein the bottom layer exhibits a notable infrared emissivity. The distinctive feature of the design effectively reduces radiative heat loss and facilitates dual-interface evaporation by heating the water surface through mid-infrared radiation. The refined design leads to a notable evaporation rate of 2.83 kg m-2 h-1. Numerical simulations and practical performance evaluations validate the effectiveness of the multilayer evaporator in actual use scenarios. This energy-recycling and dual-interface evaporation multilayered approach propels the design of high-efficiency solar-driven interfacial evaporators forward, presenting new insights into developing effective water-energy transformation systems.

2.
Plants (Basel) ; 13(2)2024 Jan 13.
Artículo en Inglés | MEDLINE | ID: mdl-38256773

RESUMEN

Potato is an important crop, used not only for food production but also for various industrial applications. With the introduction of the potato as a staple food strategy, the potato industry in China has grown rapidly. However, issues related to bacterial wilt, exacerbated by factors such as seed potato transportation and continuous cropping, have become increasingly severe in the primary potato cultivation regions of China, leading to significant economic losses. The extensive genetic diversity of Ralstonia solanacearum (R. solanacearum), which is the pathogen of bacterial wilt, has led to a lack of highly resistant potato genetic resources. There is a need to identify and cultivate potato varieties with enhanced resistance to reduce the adverse impact of this disease on the industry. We screened 55 accessions of nine different wild potato species against the bacterial wilt pathogen R. solanacearum PO2-1, which was isolated from native potato plants and belongs to phylotype II. Three accessions of two species (ACL24-2, PNT880-3, and PNT204-23) were identified with high resistance phenotypes to the tested strains. We found these accessions also showed high resistance to different phylotype strains. Among them, only PNT880-3 was capable of flowering and possessed viable pollen, and it was diploid. Consistent with the high resistance, decreased growth of R. solanacearum was detected in PNT880-3. All these findings in our study reveal that the wild potato PNT880-3 was a valuable resistance source to bacterial wilt with breeding potential.

3.
Plant J ; 116(5): 1342-1354, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37614094

RESUMEN

Miraculin-like proteins (MLPs), members of the Kunitz trypsin inhibitor (KTI) family that are present in various plants, have been discovered to have a role in defending plants against pathogens. In this study, we identified a gene StMLP1 in potato that belongs to the KTI family. We found that the expression of StMLP1 gradually increases during Ralstonia solanacearum (R. solanacearum) infection. We characterized the promoter of StMLP1 as an inducible promoter that can be triggered by R. solanacearum and as a tissue-specific promoter with specificity for vascular bundle expression. Our findings demonstrate that StMLP1 exhibits trypsin inhibitor activity, and that its signal peptide is essential for proper localization and function. Overexpression of StMLP1 in potato can enhance the resistance to R. solanacearum. Inhibiting the expression of StMLP1 during infection accelerated the infection by R. solanacearum to a certain extent. In addition, the RNA-seq results of the overexpression-StMLP1 lines indicated that StMLP1 was involved in potato immunity. All these findings in our study reveal that StMLP1 functions as a positive regulator that is induced and specifically expressed in vascular bundles in response to R. solanacearum infection.


Asunto(s)
Ralstonia solanacearum , Solanum tuberosum , Solanum tuberosum/genética , Ralstonia solanacearum/fisiología , Inhibidores de Tripsina/metabolismo , Haz Vascular de Plantas , Plantas , Enfermedades de las Plantas
4.
Hortic Res ; 10(6): uhad087, 2023 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-37334181

RESUMEN

The bacterial pathogen Ralstonia solanacearum (R. solanacearum) delivered type III secretion effectors to inhibit the immune system and cause bacterial wilt on potato. Protein phosphatases are key regulators in plant immunity, which pathogens can manipulate to alter host processes. Here, we show that a type III effector RipAS can reduce the nucleolar accumulation of a type one protein phosphatase (PP1) StTOPP6 to promote bacterial wilt. StTOPP6 was used as bait in the Yeast two-Hybrid (Y2H) assay and acquired an effector RipAS that interacts with it. RipAS was characterized as a virulence effector to contribute to R. solanacearum infection, and stable expression of RipAS in potato impaired plant resistance against R. solanacearum. Overexpression of StTOPP6 showed enhanced disease symptoms when inoculated with wild strain UW551 but not the ripAS deletion mutant, indicating that the expression of StTOPP6 facilitates the virulence of RipAS. RipAS reduced the nucleolar accumulation of StTOPP6, which occurred during R. solanacearum infection. Moreover, the association also widely existed between other PP1s and RipAS. We argue that RipAS is a virulence effector associated with PP1s to promote bacterial wilt.

5.
Mol Plant Pathol ; 24(8): 947-960, 2023 08.
Artículo en Inglés | MEDLINE | ID: mdl-37154802

RESUMEN

Ralstonia solanacearum is one of the most destructive plant-pathogenic bacteria, infecting more than 200 plant species, including potato (Solanum tuberosum) and many other solanaceous crops. R. solanacearum has numerous pathogenicity factors, and type III effectors secreted through type III secretion system (T3SS) are key factors to counteract host immunity. Here, we show that RipBT is a novel T3SS-secreted effector by using a cyaA reporter system. Transient expression of RipBT in Nicotiania benthamiana induced strong cell death in a plasma membrane-localization dependent manner. Notably, mutation of RipBT in R. solanacearum showed attenuated virulence on potato, while RipBT transgenic potato plants exhibited enhanced susceptibility to R. solanacearum. Interestingly, transcriptomic analyses suggest that RipBT may interfere with plant reactive oxygen species (ROS) metabolism during the R. solanacearum infection of potato roots. In addition, the expression of RipBT remarkably suppressed the flg22-induced pathogen-associated molecular pattern-triggered immunity responses, such as the ROS burst. Taken together, RipBT acts as a T3SS effector, promoting R. solanacearum infection on potato and presumably disturbing ROS homeostasis.


Asunto(s)
Ralstonia solanacearum , Solanum tuberosum , Virulencia , Solanum tuberosum/genética , Especies Reactivas de Oxígeno/metabolismo , Proteínas Bacterianas/metabolismo , Enfermedades de las Plantas/microbiología , Plantas Modificadas Genéticamente/metabolismo
6.
J Exp Bot ; 74(14): 4208-4224, 2023 08 03.
Artículo en Inglés | MEDLINE | ID: mdl-37086267

RESUMEN

Potato (Solanum tuberosum) is an important crop globally and is grown across many regions in China, where it ranks fourth in the list of staple foods. However, its production and quality are severely affected by bacterial wilt caused by Ralstonia solanacearum. In this study, we identified StTOPP6, which belongs to the type one protein phosphatase (TOPP) family, and found that transient knock down of StTOPP6 in potato increased resistance against R. solanacearum. RNA-seq analysis showed that knock down of StTOPP6 activated immune responses, and this defense activation partly depended on the mitogen-activated protein kinase (MAPK) signal pathway. StTOPP6 inhibited the expression of StMAPK3, while overexpression of StMAPK3 enhanced resistance to R. solanacearum, supporting the negative role of StTOPP6 in plant immunity. Consistent with the results of knock down of StTOPP6, overexpressing the phosphatase-dead mutation StTOPP6m also attenuated infection and up-regulated MAPK3, showing that StTOPP6 activity is required for disease. Furthermore, we found that StTOPP6 affected the StMAPK3-mediated downstream defense pathway, eventually suppressing the accumulation of reactive oxygen species (ROS). Consistent with these findings, plants with knock down of StTOPP6, overexpression of StTOPP6m, and overexpression of StMAPK3 all displayed ROS accumulation and enhanced resistance to R. solanacearum. Taken together, the findings of our study demonstrate that StTOPP6 negatively regulates resistance to bacterial wilt by affecting the MAPK3-mediated pathway.


Asunto(s)
Ralstonia solanacearum , Solanum tuberosum , Solanum tuberosum/metabolismo , Proteínas Quinasas Activadas por Mitógenos/genética , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Ralstonia solanacearum/fisiología , Transducción de Señal , Fosfoproteínas Fosfatasas/metabolismo , Enfermedades de las Plantas/microbiología , Resistencia a la Enfermedad/genética
7.
Front Plant Sci ; 14: 1075042, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36909411

RESUMEN

Ralstonia solanacearum is the causal agent of potato bacterial wilt, a major potato bacterial disease. Among the pathogenicity determinants, the Type III Secretion System Effectors (T3Es) play a vital role in the interaction. Investigating the avirulent T3Es recognized by host resistance proteins is an effective method to uncover the resistance mechanism of potato against R. solanacearum. Two closely related R. solanacearum strains HA4-1 and HZAU091 were found to be avirulent and highly virulent to the wild potato Solanum albicans 28-1, respectively. The complete genome of HZAU091 was sequenced in this study. HZAU091 and HA4-1 shared over 99.9% nucleotide identity with each other. Comparing genomics of closely related strains provides deeper insights into the interaction between hosts and pathogens, especially the mechanism of virulence. The comparison of type III effector repertoires between HA4-1 and HZAU091 uncovered seven distinct effectors. Two predicted effectors RipA5 and the novel effector RipBS in HA4-1 could significantly reduce the virulence of HZAU091 when they were transformed into HZAU091. Furthermore, the pathogenicity assays of mutated strains HA4-1 ΔRipS6, HA4-1 ΔRipO1, HA4-1 ΔRipBS, and HA4-1 ΔHyp6 uncovered that the absence of these T3Es enhanced the HA4-1 virulence to wild potato S. albicans 28-1. This result indicated that these T3Es may be recognized by S. albicans 28-1 as avirulence proteins to trigger the resistance. In summary, this study provides a foundation to unravel the R. solanacearum-potato interaction and facilitates the development of resistance potato against bacterial wilt.

8.
Adv Mater ; 35(20): e2300398, 2023 May.
Artículo en Inglés | MEDLINE | ID: mdl-36812399

RESUMEN

Harvesting energy from ubiquitous moisture has emerged as a promising technology, offering opportunities to power wearable electronics. However, low current density and inadequate stretching limit their integration into self-powered wearables. Herein, a high-performance, highly stretchable, and flexible moist-electric generator (MEG) is developed via molecular engineering of hydrogels. The molecular engineering involves the impregnation of lithium ions and sulfonic acid groups into the polymer molecular chains to create ion-conductive and stretchable hydrogels. This new strategy fully leverages the molecular structure of polymer chains, circumventing the addition of extra elastomers or conductors. A centimeter-sized hydrogel-based MEG can generate an open-circuit voltage of 0.81 V and a short-circuit current density of up to 480 µA cm-2 . This current density is more than ten times that of most reported MEGs. Moreover, molecular engineering improves the mechanical properties of hydrogels, resulting in a stretchability of 506%, representing the state-of-the-art level in reported MEGs. Notably, large-scale integration of the high-performance and stretchable MEGs is demonstrated to power wearables with integrated electronics, including respiration monitoring masks, smart helmets, and medical suits. This work provides fresh insights into the design of high-performance and stretchable MEGs, facilitating their application to self-powered wearables and broadening the application scenario.

11.
Small ; 18(49): e2204647, 2022 12.
Artículo en Inglés | MEDLINE | ID: mdl-36310141

RESUMEN

Liquid hydrogen carriers featuring high hydrogen content, safety, and hydrogen release on demand have motivated great endeavors for sustainable hydrogen supply. Nonetheless, direct hydrogen release is limited by the ultralow hydrogen evolution rate, while the conventional manner of extra additive and solvent addition for promoting rates greatly deteriorates its hydrogen storage density. Thus, it is still challenging to simultaneously satisfy high-performance hydrogen release and high storage density. Herein, an aerophobicity surface-based gas-liquid interface reaction strategy is proposed, which renders rapid product removal to promote dehydrogenation, fundamentally circumventing the employment of additives and solvents. Accordingly, a hierarchically porous resin-grafted reduced graphene oxide aerogel is designed. It imparts superaerophobic surface to facilitate product detachment from reactive sites, and the structure-oriented interface reaction design provides product diffusion channels and reduced diffusion resistance. As a result, the aerogel harvests a record hydrogen evolution rate (347 mmol g-1  h-1 ) in an ultrahigh-density formic acid of 19.8 g L-1 , around two times the rate promotion and ten times the density improvement compared to the state-of-the-art materials and systems. The strategy presents an approach for the dehydrogenation of liquid hydrogen carriers, e.g., formic acid, formaldehyde, and hydrazine hydrate, concurrently ensuring high-performance hydrogen release and high hydrogen storage density.


Asunto(s)
Formiatos , Hidrógeno , Difusión , Formaldehído , Solventes
12.
Curr Opin Pharmacol ; 62: 168-176, 2022 02.
Artículo en Inglés | MEDLINE | ID: mdl-35066463

RESUMEN

Type 2 diabetes mellitus (T2DM) is a complicated metabolic disease and has become one of the significant medical problems worldwide. Researchers aim to provide fine-tuned treatment for T2DM with minimal exposed side effects. Nutraceuticals are compounds or materials and emerging evidence suggests that the use of nutraceuticals has recently been recognized as a promising option for the prevention and management of T2DM, such as probiotics and prebiotics, Vitamin D, n-3 long-chain polyunsaturated fatty acids, and Plant-derived nutraceuticals. This review attempts to show the most popular nutraceuticals and review their effects and possible mechanisms in the prevention or glycemic control of T2DM.


Asunto(s)
Diabetes Mellitus Tipo 2 , Ácidos Grasos Omega-3 , Probióticos , Diabetes Mellitus Tipo 2/prevención & control , Suplementos Dietéticos , Ácidos Grasos Omega-3/uso terapéutico , Humanos , Prebióticos , Probióticos/uso terapéutico
13.
Chemosphere ; 286(Pt 1): 131657, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34351279

RESUMEN

The photocatalytic fuel cell (PFC) is a promising energy conversion technology for effective solar energy utilization, wastewater treatment, and electricity generation by photoelectrochemical reactions. Nevertheless, the discharging current output and stability of the PFC are still plagued by the low photoelectron conversion efficiency and time-varying light intensity, respectively. Herein, we integrated a RuO2 capacitive layer and a TiO2 photocatalytic layer into a capacitive photoanode, finally designing a PFC with the capacitive photoanode. Not only can the successful integration of the capacitive layer augment the discharging current, but it can also balance the solar intensity fluctuation by the ability of electron storage. The capacitive photoanode showed a high areal capacitance of 1040.7 mFcm-2 at a current density of 0.5 mAcm-2, was continuously charged and discharged for 1000 cycles, and maintained 87 % of the original capacitance after cycles. The superior rate capability, high capacitance, and good cycle performance of the capacitive photoanode originate from the "crack mud" structure in the capacitive layer. The discharging current of the capacitive photoanode was 32.0 mAcm-2 under one sun illumination, and the electrochemical performance of the capacitive photoanode was better than that of the conventional TiO2 photoanode. The capacitive photoanode PFC possessed a maximum short-circuit current of 300.0 µA⋅cm-2 at the beginning of discharge, which is independent of the light intensity. The capacitive photoanode PFC adopts a new working mode and provides a unique solution for the practical application of PFC.


Asunto(s)
Energía Solar , Purificación del Agua , Electricidad , Electrodos , Luz
14.
Nanotechnology ; 33(11)2021 Dec 22.
Artículo en Inglés | MEDLINE | ID: mdl-34874293

RESUMEN

Aqueous zinc-ion batteries (ZIBs) is a potential energy storage system due to its advantages of low cost, good safety, and high theoretical capacity (820 mAh g-1). However, the lack of cathode materials with long cycle stability severely restricts the development of ZIBs. In this paper, V2O5/ NaV6O15nanocomposites are synthesized by molten salt method in one step and used as cathode material for ZIBs, which have good electrochemical performances. The specific capacity of the materials remain 160 mAh g-1when the current density is 0.5 A g-1after 1000 cycles, and the capacity retention rate is 102.03% when the current density is 5 A g-1for 1000 cycles. This is mainly due to the large number of active sites generated by crystal defects and the synergistic interaction between the dual-phase materials, which reduces the stress of ions inserted/extracted during the Zn2+storage process and improves the electrochemical performance.

15.
Acta Diabetol ; 58(10): 1413-1423, 2021 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-34046744

RESUMEN

BACKGROUND: Diabetic kidney disease (DKD) is a serious complication of diabetes mellitus and results in serious public health problems. Although a great number of studies have been performed to elucidate the mechanisms of this disease, these mechanisms remain largely unknown. METHODS: Cell and animal models were first constructed using human renal proximal tubule cells stimulated by high glucose (HG) and mice induced by streptozotocin (STZ). After Klotho overexpression, Klotho expression was assessed by RT-PCR and western blot, immunofluorescence; autophagy and AMPK/ERK proteins were confirmed using western blot or immunohistochemical assay; the autophagosomes were observed by transmission electron microscope; the pathological structure, fibrosis, polysaccharides and glycogen of kidney were evaluated by H&E staining, Masson staining and PAS staining. RESULTS: We first confirmed that Klotho expression and autophagic activity were reduced in DM mice and HG-induced human renal proximal tubule cells. Besides, overexpression of Klotho could significantly enhance autophagy and AMPK and ERK1/2 activities in vivo and in vitro, which also could be abolished by selective AMPK inhibitor and ERK activator. Moreover, we proved that Klotho could inhibit hyperglycemia-induced renal tubular damage. CONCLUSION: In summary, our results proved that Klotho improved renal tubular cell autophagy via the AMPK and ERK pathways and played a role in renal protection. These findings provide new insight into the mechanism of Klotho and autophagy in DKD.


Asunto(s)
Diabetes Mellitus , Nefropatías Diabéticas , Proteínas Quinasas Activadas por AMP/genética , Animales , Autofagia , Nefropatías Diabéticas/genética , Células Epiteliales , Riñón , Ratones
16.
Biochem Biophys Res Commun ; 550: 120-126, 2021 04 23.
Artículo en Inglés | MEDLINE | ID: mdl-33691198

RESUMEN

Ralstonia solanacearum causes bacterial wilt disease in a broad range of plants, primarily through type Ⅲ secreted effectors. However, the R. solanacearum effectors promoting susceptibility in host plants remain limited. In this study, we determined that the R. solanacearum effector RipV2 functions as a novel E3 ubiquitin ligase (NEL). RipV2 was observed to be locali in the plasma membrane after translocatio into plant cells. Transient expression of RipV2 in Nicotiana benthamiana could induce cell death and suppress the flg22-induced pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) responses, mediating such effects as attenuation of the expression of several PTI-related genes and ROS bursts. Furthermore, we demonstrated that the conserved catalytic residue is highly important for RipV2. Transient expression of the E3 ubiquitin ligase catalytic mutant RipV2 C403A alleviated the PTI suppression ability and cell death induction, indicating that RipV2 requires its E3 ubiquitin ligase activity for its role in plant-microbe interactions. More importantly, mutation of RipV2 in R. solanacearum reduces the virulence of R. solanacearum on potato. In conclusion, we identified a NEL effector that is required for full virulence of R. solanacearum by suppressing plant PTI.


Asunto(s)
Moléculas de Patrón Molecular Asociado a Patógenos/antagonistas & inhibidores , Inmunidad de la Planta , Ralstonia solanacearum/enzimología , Solanum tuberosum/inmunología , Solanum tuberosum/microbiología , Ubiquitina-Proteína Ligasas/genética , Ubiquitina-Proteína Ligasas/metabolismo , Virulencia , Secuencias de Aminoácidos , Biocatálisis , Muerte Celular , Membrana Celular/enzimología , Cisteína/metabolismo , Flagelina/química , Flagelina/inmunología , Moléculas de Patrón Molecular Asociado a Patógenos/inmunología , Fragmentos de Péptidos/química , Fragmentos de Péptidos/inmunología , Ralstonia solanacearum/genética , Ubiquitina-Proteína Ligasas/química , Virulencia/genética
17.
Mol Plant Microbe Interact ; 34(4): 337-350, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33332146

RESUMEN

The infection of potato with Ralstonia solanacearum UW551 gives rise to bacterial wilt disease via colonization of roots. The type III secretion system (T3SS) is a determinant factor for the pathogenicity of R. solanacearum. To fully understand perturbations in potato by R. solanacearum type III effectors(T3Es), we used proteomics to measure differences in potato root protein abundance after inoculation with R. solanacearum UW551 and the T3SS mutant (UW551△HrcV). We identified 21 differentially accumulated proteins. Compared with inoculation with UW551△HrcV, 10 proteins showed significantly lower abundance in potato roots after inoculation with UW551, indicating that those proteins were significantly downregulated by T3Es during the invasion. To identify their functions in immunity, we silenced those genes in Nicotiana benthamiana and tested the resistance of the silenced plants to the pathogen. Results showed that miraculin, HBP2, and TOM20 contribute to immunity to R. solanacearum. In contrast, PP1 contributes to susceptibility. Notably, none of four downregulated proteins (HBP2, PP1, HSP22, and TOM20) were downregulated at the transcriptional level, suggesting that they were significantly downregulated at the posttranscriptional level. We further coexpressed those four proteins with 33 core T3Es. To our surprise, multiple effectors were able to significantly decrease the studied protein abundances. In conclusion, our data showed that T3Es of R. solanacearum could subvert potato root immune-related proteins in a redundant manner.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.


Asunto(s)
Ralstonia solanacearum , Solanum tuberosum , Proteínas Bacterianas/genética , Enfermedades de las Plantas , Proteómica , Sistemas de Secreción Tipo III/genética
18.
Plant Cell Rep ; 39(9): 1235-1248, 2020 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-32666195

RESUMEN

KEY MESSAGE: Clarification of the genome composition of the potato + eggplant somatic hybrids cooperated with transcriptome analysis efficiently identified the eggplant gene SmPGH1 that contributes to bacterial wilt resistance. The cultivated potato is susceptible and lacks resistance to bacterial wilt (BW), a soil-borne disease caused by Ralstonia solanacearum. It also has interspecies incompatibility within Solanaceae plants. Previously, we have successfully conducted the protoplast fusion of potato and eggplant and regenerated somatic hybrids that showing resistance to eggplant BW. For efficient use of these novel germplasm and improve BW resistance of cultivated potato, it is essential to dissect the genetic basis of the resistance to BW obtained from eggplant. The strategy of combining genome composition and transcriptome analysis was established to explore the gene that confers BW resistance to the hybrids. Genome composition of the 90 somatic hybrids was studied using genomic in situ hybridization coupled with 44 selected eggplant-specific SSRs (smSSRs). The analysis revealed a diverse set of genome combinations among the hybrids and showed a possibility of integration of alien genes along with the detection of 7 smSSRs linked to BW resistance (BW-linked SSRs) in the hybrids. Transcriptome comparison between the resistant and susceptible gene pools identified a BW resistance associated gene, smPGH1, which was significantly induced by R. solanacearum in the resistant pool. Remarkably, smPGH1 was co-localized with the BW-linked SSR emh01E15 on eggplant chromosome 9, which was further confirmed that smPGH1 was activated by R. solanacearum only in the resistant hybrids. Taken together, the identified gene smPGH1 and BW-linked SSRs have provided novel genetic resources that will aid in potato breeding for BW resistance.


Asunto(s)
Resistencia a la Enfermedad/genética , Genoma de Planta , Proteínas de Plantas/genética , Solanum melongena/genética , Solanum tuberosum/genética , Cromosomas de las Plantas , Regulación de la Expresión Génica de las Plantas , Células Híbridas , Repeticiones de Microsatélite , Enfermedades de las Plantas/microbiología , Ralstonia solanacearum/patogenicidad , Solanum melongena/microbiología , Solanum tuberosum/microbiología
19.
Front Microbiol ; 10: 1893, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31474968

RESUMEN

Ralstonia solanacearum, which causes bacterial wilt in a broad range of plants, is considered a "species complex" due to its significant genetic diversity. Recently, we have isolated a new R. solanacearum strain HA4-1 from Hong'an county in Hubei province of China and identified it being phylotype I, sequevar 14M (phylotype I-14M). Interestingly, we found that it can cause various disease symptoms among different potato genotypes and display different pathogenic behavior compared to a phylogenetically related strain, GMI1000. To dissect the pathogenic mechanisms of HA4-1, we sequenced its whole genome by combined sequencing technologies including Illumina HiSeq2000, PacBio RS II, and BAC-end sequencing. Genome assembly results revealed the presence of a conventional chromosome, a megaplasmid as well as a 143 kb plasmid in HA4-1. Comparative genome analysis between HA4-1 and GMI1000 shows high conservation of the general virulence factors such as secretion systems, motility, exopolysaccharides (EPS), and key regulatory factors, but significant variation in the repertoire and structure of type III effectors, which could be the determinants of their differential pathogenesis in certain potato species or genotypes. We have identified two novel type III effectors that were probably acquired through horizontal gene transfer (HGT). These novel R. solanacearum effectors display homology to several YopJ and XopAC family members. We named them as RipBR and RipBS. Notably, the copy of RipBR on the plasmid is a pseudogene, while the other on the megaplasmid is normal. For RipBS, there are three copies located in the megaplasmid and plasmid, respectively. Our results have not only enriched the genome information on R. solanacearum species complex by sequencing the first sequevar 14M strain and the largest plasmid reported in R. solanacearum to date but also revealed the variation in the repertoire of type III effectors. This will greatly contribute to the future studies on the pathogenic evolution, host adaptation, and interaction between R. solanacearum and potato.

20.
Mol Plant Pathol ; 20(4): 547-561, 2019 04.
Artículo en Inglés | MEDLINE | ID: mdl-30499228

RESUMEN

Both Solanum tuberosum and Ralstonia solanacearum phylotype IIB originated in South America and share a long-term co-evolutionary history. However, our knowledge of potato bacterial wilt pathogenesis is scarce as a result of the technical difficulties of potato plant manipulation. Thus, we established a multiple screening system (virulence screen of effector mutants in potato, growth inhibition of yeast and transient expression in Nicotiana benthamiana) of core type III effectors (T3Es) of a major potato pathovar of phylotype IIB, to provide more research perspectives and biological tools. Using this system, we identified four effectors contributing to virulence during potato infection, with two exhibiting multiple phenotypes in two other systems, including RipAB. Further study showed that RipAB is an unknown protein with a nuclear localization signal (NLS). Furthermore, we generated a ripAB complementation strain and transgenic ripAB-expressing potato plants, and subsequent virulence assays confirmed that R. solanacearum requires RipAB for full virulence. Compared with wild-type potato, transcriptomic analysis of transgenic ripAB-expressing potato plants showed a significant down-regulation of Ca2+ signalling-related genes in the enriched Plant-Pathogen Interaction (PPI) gene ontology (GO) term. We further verified that, during infection, RipAB is required for the down-regulation of four Ca2+ sensors, Stcml5, Stcml23, Stcml-cast and Stcdpk2, and a Ca2+ transporter, Stcngc1. Further evidence showed that the immune-associated reactive oxygen species (ROS) burst is attenuated in ripAB transgenic potato plants. In conclusion, a systematic screen of conserved R. solanacearum effectors revealed an important role for RipAB, which interferes with Ca2+ -dependent gene expression to promote disease development in potato.


Asunto(s)
Ralstonia solanacearum/patogenicidad , Solanum tuberosum/inmunología , Solanum tuberosum/microbiología , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Señalización del Calcio/fisiología , Enfermedades de las Plantas/inmunología , Enfermedades de las Plantas/microbiología , Inmunidad de la Planta/fisiología , Ralstonia solanacearum/inmunología
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