Phytophthora capsici is the most devastating pathogen for chile pepper production worldwide and current management strategies are not effective. The population structure of the pathogen is highly variable and few sources of widely applicable host resistance have been identified. Recent genomic advancements in the host and the pathogen provide important insights into the difficulties reported by epidemiological and physiological studies published over the past century. This review highlights important challenges unique to this complex pathosystem and suggests strategies for resistance breeding to help limit losses associated with P. capsici.

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Challenges and Strategies for Breeding Resistance in Capsicum annuum to the Multifarious Pathogen, Phytophthora capsici

Pectate lyases: Their role in plants and importance in fruit ripening.

Oomycetes are a group of filamentous eukaryotic microorganisms that have colonized all terrestrial and oceanic ecosystems, and they include prominent plant pathogens. The Aphanomyces genus is unique in its ability to infect both plant and animal species, and as such exemplifies oomycete versatility in adapting to different hosts and environments. Dissecting the underpinnings of oomycete diversity provides insights into their specificity and pathogenic mechanisms. By carrying out genomic analyses of the plant pathogen A. euteiches and the crustacean pathogen A. astaci, we show that host specialization is correlated with specialized secretomes that are adapted to the deconstruction of the plant cell wall in A. euteiches and protein degradation in A. astaci. The A. euteiches genome is characterized by a large repertoire of small secreted protein (SSP)-encoding genes that are highly induced during plant infection, and are not detected in other oomycetes. Functional analysis revealed an SSP from A. euteiches containing a predicted nuclear-localization signal which shuttles to the plant nucleus and increases plant susceptibility to infection. Collectively, our results show that Aphanomyces host adaptation is associated with evolution of specialized secretomes and identify SSPs as a new class of putative oomycete effectors.

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Genomics analysis of Aphanomyces spp. identifies a new class of oomycete effector associated with host adaptation

Abstract Soil organic carbon (SOC) is a crucial component that significantly affects the soil fertility, soil remediation, and carbon sequestration. Here, we review the redox-induced transformation of potentially toxic elements (PTEs) through the abiotic impact of SOC. The complex composition of SOC includes humus, pyrogenic carbon (e.g., biochar), dissolved organic matter, and anthropogenic carbon (e.g., compost), with varying concentrations and properties. The primary redox moieties on organic carbon are surface functionalities (e.g., phenol, quinone, and N/S-containing functional groups), environmentally persistent free radicals, and graphitic structures, and their contents are highly variable. Owing to these rich redox moieties, organic carbon can directly affect the reduction and oxidation of PTEs in the soil, such as Cr(VI) reduction and As(III) oxidation. In addition, the interactions between organic carbon and soil redox moieties (i.e., O 2 , Fe, and Mn minerals) cause the transformation of PTEs. The formation of reactive oxygen species, Fe(II), and Mn(III)/Mn(II) is the main contributor to the redox-induced transformation of PTEs, including Cr(VI) reduction and As(III)/Cr(III)/Tl(I) oxidation. We articulated both the positive and negative effects of organic carbon on the redox-induced transformation of PTEs, which could guide soil remediation efforts. Further scientific studies are necessary to better understand the potential transformations of PTEs by SOC, considering the complicated soil moieties, variable organic carbon composition, and both biotic and abiotic transformations of PTEs in the environment. Graphical Abstract 

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Redox-induced transformation of potentially toxic elements with organic carbon in soil

Abstract Nanomaterials (NMs) are able to interact with natural organic matter (NOM) such that NOM is adsorbed on the surface of NMs to form an ecological corona (eco-corona). The formation of an eco-corona can greatly influence the behavior, risk and fate of NMs in the environment. A systematic understanding of the impacts of an eco-corona on the hazards of NMs is crucial for NMs risk assessment in the aquatic environment. Herein, the mechanisms of the formation of an eco-corona were reviewed based on the representative literatures and their generality was discussed on the basis of the type of NMs, the type of NOM and the environmental conditions. The effects of an eco-corona on the bioaccumulation and toxicity of NMs for aquatic organisms were systematically discussed through reported studies. The results showed that an eco-corona could alter the toxicity of NMs by changing the dissolution of NMs, adhesion of NMs and the damages to bio-membranes, internalization, and the generation of NMs-induced reactive oxygen species. The dual effects of an eco-corona on the toxicity/accumulation of NMs were widely present because of the complex molecular composition of NOM, the diverse types of NMs, and the variable environmental conditions. The effects of an eco-corona on the fate and the effects of other pollutants (such as metals and organic pollutants) were also carefully reviewed. The results showed that more research is needed to investigate the effect of an eco-corona through the development of novel techniques, mathematical modeling, and mesocosm studies. Graphical Abstract 

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A critical review on the biological impact of natural organic matter on nanomaterials in the aquatic environment

Environmental and health effects of graphene-family nanomaterials: Potential release pathways, transformation, environmental fate and health risks

Pectate lyases (PL) play a critical role in pectin degradation. PL have been extensively studied in major bacterial and fungal pathogens of a wide range of plant species. However, the contribution ...

https://apsjournals.apsnet.org/doi/pdf/10.1094/MPMI-11-14-0352-R

Characterization of Cell-Death-Inducing Members of the Pectate Lyase Gene Family in Phytophthora capsici and Their Contributions to Infection of Pepper.

Summary

SDA1 encodes a highly conserved protein that is widely distributed in eukaryotic organisms. SDA1 is essential for cell cycle progression and organization of the actin cytoskeleton in yeasts and humans. In this study, we identified a Phytophthora capsici orthologue of yeast SDA1, named PcSDA1. In P. capsici, PcSDA1 is strongly expressed in three asexual developmental states (mycelium, sporangia and germinating cysts), as well as late in infection. Silencing or overexpression of PcSDA1 in P. capsici transformants affected the growth of hyphae and sporangiophores, sporangial development, cyst germination and zoospore release. Phalloidin staining confirmed that PcSDA1 is required for organization of the actin cytoskeleton. Moreover, 4′,6-diamidino-2-phenylindole (DAPI) staining and PcSDA1-green fluorescent protein (GFP) fusions revealed that PcSDA1 is involved in the regulation of nuclear distribution in hyphae and sporangia. Both silenced and overexpression transformants showed severely diminished virulence. Thus, our results suggest that PcSDA1 plays a similar role in the regulation of the actin cytoskeleton and nuclear division in this filamentous organism as in non-filamentous yeasts and human cells.

Phytophthora capsici homologue of the cell cycle regulator SDA1 is required for sporangial morphology, mycelial growth and plant infection.

Nanomaterials have been widely used in electrochemistry, sensors, medicine among others applications, causing its inevitable environmental exposure. A raising question is the "carrier" effect due to unique surface properties of nanomaterials, which may collectively impact the bioavailability, toxicokinetic, distribution and biological effects of classic toxicants. Noteworthy, this aspect of information remains largely unexplored.Here, we deliberately selected two entities to mimic this scenario. One is graphene oxide (GO), which is made in ton quantity with huge surface-area that provides hydrophilicity and π-π interaction to certain chemicals of unique structures. The other is Microcystin-LR (MCLR), a representative double-bond rich liver-toxic endotoxin widely distributed in aquatic-system. Firstly, the adsorption of GO and MCLR after meeting under environmental conditions was explored, and then we focused on the toxicological effect and related mechanism of GO-MCLR complex on human skin cutin forming cells (HaCaT cells) and normal liver cells (L02 cells).Abiotically, our study demonstrated that GO could effectively adsorb MCLR through hydrogen bonding and π-π interaction, the oxidation degree of GO-MCLR decreased significantly and surface defect level raised. Compared to GO or MCLR, GO-MCLR was found to induce more remarkable apoptosis and ferroptosis in both HaCaT and L02 cells. The underlying mechanism was that GO-MCLR induced stronger intracellular reactive oxygen species (ROS) and mtROS generation, followed by Fe2+ accumulation, mitochondrial dysfunction and cytoskeletal damage.These results suggest that the GO-MCLR complex formed by GO adsorption of MCLR may exhibit more toxic effects than the single material, which demonstrates the necessity for assessing nano-toxicant complexity. Our discovery may serve as a new toxicological paradigm in which nanomaterial mediated surface adsorption effects could impact the degree of cytotoxicity and toxicological mechanisms of classic toxins. 

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Safety assessment of graphene oxide and microcystin-LR complex: a toxicological scenario beyond physical mixture

The invention discloses a fungus pathogenesis-related protein PcCAT1 and its coding gene and use. The fungus pathogenesis-related protein PcCAT1 is a1), a protein with an amino acid sequence shown in the sequence 1 in the sequence table, a2), a fused protein which is obtained by connection of labels to the end N and/or end C of a protein shown in the sequence 2 in the sequence table, or a3), a protein which is derived from the amino acid sequence shown in the sequence 2 in the sequence table by replacement and/or deletion and/or addition of one or more amino acid residues. An experiment proves that the fungus pathogenesis-related protein PcCAT1 has great values in regulation and control of phytophthora capsici pathogenicity to plants and prevention and treatment on phytoph-thora capsici leonian.

Xiaomeng Ding

Papers

Environmental and health effects of graphene-family nanomaterials: Potential release pathways, transformation, environmental fate and health risks

Characterization of Cell-Death-Inducing Members of the Pectate Lyase Gene Family in Phytophthora capsici and Their Contributions to Infection of Pepper.

Phytophthora capsici homologue of the cell cycle regulator SDA1 is required for sporangial morphology, mycelial growth and plant infection.

Safety assessment of graphene oxide and microcystin-LR complex: a toxicological scenario beyond physical mixture

Fungus pathogenesis-related protein PcCAT1 and its coding gene and use