Identification and Characterization of WRKY41, a Gene Conferring Resistance to Powdery Mildew in Wild Tomato (Solanum habrochaites) LA1777.

WRKYs, a large family of transcription factors, are involved in plant response to biotic and abiotic stresses, but the role of them in tomato resistance to Oidium neolycopersici is still unclear. In this study, we evaluate the role of WRKYs in powdery mildew-resistant wild tomato (Solanum habrochaites) LA1777 defense against O. neolycopersici strain lz (On-lz) using a combination of omics, classical plant pathology- and cell biology-based approaches. A total of 27 WRKYs, belonging to group I, II, and III, were identified as differentially expressed genes in LA1777 against On-lz. It was found that expression of ShWRKY41 was increased after Pseudomonas syringae pv. tomato (Pst) DC3000, On-lz and Botrytiscinerea B05 inoculation or ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) treatment. GUS staining of ShWRKY41 promoter indicated that the expression of ShWRKY41 could be induced by SA and ethylene. Furthermore, ShWRKY41 gene silencing reduced the resistance to On-lz infection by decreasing the generation of H2O2 and HR in LA1777 seedlings. Overall, our research suggests that ShWRKY41 plays a positive role in defense activation and host resistance to O. neolycopersici in wild tomato (S. habrochaites) LA1777.

Salicylic acid carboxyl glucosyltransferase UGT87E7 regulates disease resistance in Camellia sinensis.

Plant immune response following pathogenic infection is regulated by plant hormones, and salicylic acid (SA) and its sugar conjugates play important roles in establishing basal resistance. Here, the important pathogen Pseudopestalotiopsis camelliae-sinensis (Pcs) was isolated from tea gray blight, one of the most destructive diseases in tea plantations. Transcriptomic analysis led to the discovery of the putative Camellia sinensis UDP-glucosyltransferase CsUGT87E7 whose expression was significantly induced by SA application and Pcs infection. Recombinant CsUGT87E7 glucosylates SA with a Km value of 12 µM to form SA glucose ester (SGE). Downregulation reduced the accumulation of SGE, and CsUGT87E7-silenced tea plants exhibited greater susceptibility to pathogen infection than control plants. Similarly, CsUGT87E7-silenced tea leaves accumulated significantly less SA after infection and showed reduced expression of pathogenesis-related genes. These results suggest that CsUGT87E7 is an SA carboxyl glucosyltransferase that plays a positive role in plant disease resistance by modulating SA homeostasis through a mechanism distinct from that described in Arabidopsis (Arabidopsis thaliana). This study provides insight into the mechanisms of SA metabolism and highlights the role of SGE in the modulation of plant disease resistance.

Evaluation of prophylactic efficacy of cinnamaldehyde in murine model against Paradendryphiella arenariae mycotoxin tenuazonic acid-induced oxidative stress and organ toxicity.

Cinnamaldehyde (Cin) is a natural product obtained from cinnamon and is reported to have a potential anti-fungal, anti-oxidant, anti-inflammatory and anticancer effect. The present study investigated the possible protective role of Cin against tenuazonic acid-induced mycotoxicity in the murine model. Tenuazonic acid (TeA), a toxin produced by Alternaria is a common contaminant in tomato and tomato-based products. Here, Swiss male mice were administered with TeA isolated from Paradendryphiella arenariae (MW504999) (source-tomato) through injection (238 µg/kg BW) and ingestion (475 µg/kg BW) routes for 2 weeks. Thereafter, the prophylaxis groups were treated with Cin (210 mg/kg BW). The experiment was carried out for 8 weeks. The treated groups were compared to the oral and intra-peritoneal experimental groups that received the toxin solely for 8 weeks. Haematological, histopathological and biochemical aspects of the experimental and the control mice were analysed. Sub-chronic intoxication of mice with TeA showed elevated malondialdehyde (MDA), reduced catalase (CAT) and superoxide dismutase (SOD) production; abnormal levels of aspartate transaminase (AST) and alanine transaminase (ALT). Treatment with Cin reversed TeA-induced alterations of antioxidant defense enzyme activities and significantly prevented TeA-induced organ damage. Thus, cinnamaldehyde showed therapeutic effects and toxicity reduction in TeA induced mycotoxicosis.

Bioactivites of Penicillium citrinum isolated from a medicinal plant Swertia chirayita.

Endophytes associated with plants have the property to produce active biomolecules with their possible applications in agro-industrial sectors. This study provides a project work on analyzing various activities of fungal endophytes isolated from Swertia chirayita of Sikkim Himalayan region. Among several fungal endophytes screened, isolate UTCRF6 was found most active with the secretion of enzymes protease, cellulase, amylase and chitinase, as well as other metabolites Indoleacetic acid and siderophores. This endophyte was found active in restricting the growth of phyto-pathogens, including strains of Fusarium solani, Colletotrichum gloeosporioides, Alternaria alternata, Pestalotiopsis theae and Sclerotinia sclerotiorum. Morphological and molecular studies of this endophytic fungus showed similarity with Penicillium citrinum.

Antifungal Biphenyl Derivatives from Sorbus pohuashanensis Leaves Infected by Alternaria tenuissi and Their Effect against Crop Pathogens.

Eight natural biphenyl-type phytoalexins exhibiting antifungal effect were isolated from the leaves of Sorbus pohuashanensis, which invaded by Alternaria tenuissi, and their growth inhibition rate towards A. tenuissi were 50.3 %, 54.0 %, 66.4 %, 58.8 %, 48.5 %, 51.0 %, 33.3 %, and 37.0 %, respectively. In vivo activity assay verified the protective effect of these natural biphenyls on tobacco leaves. The observation of mycelial morphology revealed that these compounds possessed adverse effects on mycelial growth of A. tenuissi. Subsequently, the most potent active compounds, 3',4',5'-trimethoxy[1,1'-biphenyl]-4-ol (3) and 3,4,4',5-tetramethoxy-1,1'-biphenyl (4), were conducted to the further antifungal evaluation and showed significant activity against the other four crop pathogens, Fusarium graminearum, Helminthosporium maydis, Sclerotinia sclerotiorum, and Exserohilum turcicum. Further, the structure-activity relationships and biosynthesis of these compounds were speculated in this work.

Evaluation of Seven Essential Oils as Seed Treatments against Seedborne Fungal Pathogens of Cucurbita maxima.

Essential oils are gaining interest as environmentally friendly alternatives to synthetic fungicides for management of seedborne pathogens. Here, seven essential oils were initially tested in vivo for disinfection of squash seeds (Cucurbita maxima) naturally contaminated by Stagonosporopsis cucurbitacearum, Alternaria alternata, Fusarium fujikuro, Fusarium solani, Paramyrothecium roridum, Albifimbria verrucaria, Curvularia spicifera, and Rhizopus stolonifer. The seeds were treated with essential oils from Cymbopogon citratus, Lavandula dentata, Lavandula hybrida, Melaleuca alternifolia, Laurus nobilis, and Origanum majorana (#1 and #2). Incidence of S. cucurbitacearum was reduced, representing a range between 67.0% in L. nobilis to 84.4% in O. majorana #2. Treatments at 0.5 mg/mL essential oils did not affect seed germination, although radicles were shorter than controls, except with C. citratus and O. majorana #1 essential oils. Four days after seeding, seedling emergence was 20%, 30%, and 10% for control seeds and seeds treated with C. citratus essential oil (0.5 mg/mL) and fungicides (25 g/L difenoconazole plus 25 g/L fludioxonil). S. cucurbitacearum incidence was reduced by ~40% for plantlets from seeds treated with C. citratus essential oil. These data show the effectiveness of this essential oil to control the transmission of S. cucurbitacearum from seeds to plantlets, and thus define their potential use for seed decontamination in integrated pest management and organic agriculture.

GhMYB4 downregulates lignin biosynthesis and enhances cotton resistance to Verticillium dahliae.

KEY MESSAGE: GhMYB4 acts as a negative regulator in lignin biosynthesis, which results in alteration of cell wall integrity and activation of cotton defense response. Verticillium wilt of cotton (Gossypium hirsutum) caused by the soil-borne fungus Verticillium dahliae (V. dahliae) represents one of the most important constraints of cotton production worldwide. Mining of the genes involved in disease resistance and illuminating the molecular mechanisms that underlie this resistance is of great importance in cotton breeding programs. Defense-induced lignification in plants is necessary for innate immunity, and there are reports of a correlation between increased lignification and disease resistance. In this study, we present an example in cotton whereby plants with reduced lignin content also exhibit enhanced disease resistance. We identified a negative regulator of lignin synthesis, in cotton encoded in GhMYB4. Overexpression of GhMYB4 in cotton and Arabidopsis enhanced resistance to V. dahliae  with reduced lignin deposition. Moreover, GhMYB4 could bind the promoters of several genes involved in lignin synthesis, such as GhC4H-1, GhC4H-2, Gh4CL-4, and GhCAD-3, and impair their expression. The reduction of lignin content in GhMYB4-overexpressing cotton led to alterations of cell wall integrity (CWI) and released more oligogalacturonides (OGs) which may act as damage-associated molecular patterns (DAMPs) to stimulate plant defense responses. In support of this hypothesis, exogenous application with polygalacturonic acid (PGA) in cotton activated biosynthesis of jasmonic acid (JA) and JA-mediated defense against V. dahliae, similar to that described for cotton plants overexpressing GhMYB4. This study provides a new candidate gene for cotton disease-resistant breeding and an increased understanding of the relationship between lignin synthesis, OG release, and plant immunity.

Structural Alteration of Rice Pectin Affects Cell Wall Mechanical Strength and Pathogenicity of the Rice Blast Fungus Under Weak Light Conditions.

Pectin, a component of the plant cell wall, is involved in cell adhesion and environmental adaptations. We generated OsPG-FOX rice lines with little pectin due to overexpression of the gene encoding a pectin-degrading enzyme [polygalacturonase (PG)]. Overexpression of OsPG2 in rice under weak light conditions increased the activity of PG, which increased the degradation of pectin in the cell wall, thereby reducing adhesion. Under weak light conditions, the overexpression of OsPG decreased the pectin content and cell adhesion, resulting in abnormally large intercellular gaps and facilitating invasion by the rice blast fungus. OsPG2-FOX plants had weaker mechanical properties and greater sensitivity to biotic stresses than wild-type (WT) plants. However, the expression levels of disease resistance genes in non-infected leaves of OsPG2-FOX were more than twice as high as those of the WT and the intensity of disease symptoms was reduced, compared with the WT. Under normal light conditions, overexpression of OsPG2 decreased the pectin content, but did not affect cell adhesion and sensitivity to biotic stresses. Therefore, PG plays a role in regulating intercellular adhesion and the response to biotic stresses in rice.

New insights into the specificity and processivity of two novel pectinases from Verticillium dahliae.

Pectin, the major non-cellulosic component of primary cell wall can be degraded by polygalacturonases (PGs) and pectin methylesterases (PMEs) during pathogen attack on plants. We characterized two novel enzymes, VdPG2 and VdPME1, from the fungal plant pathogen Verticillium dahliae. VdPME1 was most active on citrus methylesterified pectin (55-70%) at pH 6 and a temperature of 40 °C, while VdPG2 was most active on polygalacturonic acid at pH 5 and a temperature of 50 °C. Using LC-MS/MS oligoprofiling, and various pectins, the mode of action of VdPME1 and VdPG2 were determined. VdPME1 was shown to be processive, in accordance with the electrostatic potential of the enzyme. VdPG2 was identified as endo-PG releasing both methylesterified and non-methylesterified oligogalacturonides (OGs). Additionally, when flax roots were used as substrate, acetylated OGs were detected. The comparisons of OGs released from Verticillium-susceptible and partially resistant flax cultivars identified new possible elicitor of plant defence responses.

Comparative Anatomical Responses of Tolerant and Susceptible European Plum Varieties to Black Knot Disease.

Plums are affected by a cancerous disease called "black knot disease" caused by the fungus Apiosporina morbosa. It affects both Japanese (Prunus salicina) and European (Prunus domestica) plums equally. To understand the spread of the disease, histological analysis was performed in two different European plum cultivars (susceptible and tolerant). Light and scanning electron microscope (SEM) analyses confirmed the presence of the growing hyphae in the internal tissues of the susceptible trees. By using stereoscopic analysis with a fluorescence filter, we were able to detect the hyphae in the visible lesion area. At about 2 inches from above and below the knots, no spore or hypha were visible with the light microscope. However, SEM images showed strong evidence that the fungus is capable of migrating to adjacent vessels in the susceptible plum genotype. In fact, at that distance below and above the knots, conidia were detected inside xylem vessels suggesting a systemic movement of the fungus that has not been shown so far. No symptoms were observed in the resistant genotype. Starch granules, vessel occlusions, and lipid droplets were the main distinguishable characteristics between susceptible and tolerant varieties.

Antifungal efficacy of isavuconazole and liposomal amphotericin B in a rabbit model of Exserohilum rostratum meningoencephalitis: A preclinical paradigm for management of CNS phaeohyphomycosis.

Treatment options for Exserohilum rostratum meningoencephalitis and other causes of phaeohyphomycosis of the central nervous system (CNS) are limited, while mortality and morbidity remain high. We therefore evaluated isavuconazole, a new antifungal triazole in comparison to liposomal amphotericin B (LAMB), in vitro and in the rabbit model of Exserohilum rostratum meningoencephalitis. We hypothesized that isavuconazole alone or in combination with LAMB or micafungin may be alternative options for treatment of CNS phaeohyphomycosis. We therefore investigated the in vitro antifungal activity of isavuconazole alone or in combination with amphotericin B deoxycholate (DAMB) or micafungin and efficacy of treatment with isavuconazole and LAMB in a rabbit model of experimental E. rostratum meningoencephalitis. Combination checkerboard plates were used to determine the minimum inhibitory concentrations, minimal lethal concentrations, fractional inhibitory concentration indices, and Bliss surface analysis of isavuconazole and amphotericin B deoxycholate (DAMB), either alone or in combination. As there were no in vitro synergistic or antagonistic interactions for either combination of antifungal agents against the E. rostratum isolates, in vivo studies were conducted with isavuconazole and LAMB as monotherapies. Rabbits were divided in following groups: treated with isavuconazole at 60 mg/kg/d (ISAV60), LAMB at 5.0 (LAMB5), 7.5 (LAMB7.5), and 10 mg/kg/d (LAMB10), and untreated controls (UC). In ISAV60-, LAMB5-, LAMB7.5-, and LAMB10-treated rabbits, significant reductions of fungal burden of E. rostratum in cerebral, cerebellar, and spinal cord tissues (P < 0.01) were demonstrated in comparison to those of UC. These antifungal effects correlated with significant reduction of CSF (1→3)-ß-D-glucan levels vs UC (P < 0.05). These data establish new translational insights into treatment of CNS phaeohyphomycosis.

Genetic diversity studies based on morpho-pathological and molecular variability of the Sclerotinia sclerotiorum population infecting potato (Solanum tuberosum L.).

White mould or stem rot, caused by Sclerotinia sclerotiorum (Lib.) de Bary, is a devastating fungal disease found in major potato cultivation areas worldwide. The aim of this study was to characterize genetic diversity in the S. sclerotiorum population from the main potato producing regions of India by means of morphological (mycelial growth, colony colour, number and distribution pattern of sclerotia) and molecular characteristics, as well as to evaluate the virulence of S. sclerotiorum isolates in potato for the first time. Among the S. sclerotiorum population analyzed, high phenotypic and genotypic diversity were observed. Using all the morphological characteristics, a dendrogram was constructed based on Gower's similarity coefficient that distributed all the isolates into three clusters at the 0.62 similarity coefficient. Carpogenic germination of apothecia revealed that larger sclerotia produced a greater number of apothecia while smaller sclerotia produced fewer apothecia. Pathogenicity test results revealed that out of 25 isolates, seven were highly aggressive, 14 were moderate and four had low aggressiveness, whilst isolates from Punjab were more pathogenic than those of Uttar Pradesh. Phylogenetic analysis of universal rice primer polymorphism showed high genetic variability within the isolates that grouped all the isolates in three evolutionary lineages in the resulting dendrogram and showed partial relationship with geographical locations of the isolates. Further, the findings suggest the occurrence of higher heterogeneity and genetic diversity among the S. sclerotiorum isolates that indicates the existence of both clonal and sexual reproduction in the pathogen population of potato producing areas in India.

Identification and characterization of fungi associated with blister blight lesions of tea (Camellia sinensis L. Kuntze) isolated from Meghalaya, India.

Diseases in plants are mostly caused by fungi. Fungal interactions with the host can be either biotrophic, necrotrophic or hemibiotrophic. Synergistic polymicrobial interactions have been recently recognized that can also attribute to the occurrence of complex plant diseases. Tea is one of the most widely consumed beverages worldwide, although tea plants are affected by many different diseases causing a significant reduction in global tea production. Blister blight is one such serious and damaging leaf disease of tea. An assessment of blister blight disease was carried out at the tea development center in Umsning, Meghalaya. A considerable number of tea varieties showed characteristic blister blight symptoms that ranged from preliminary yellow spots in the upper leaf surface, matured white sporulating blisters in the lower leaf surface, and delayed brown necrotic lesions throughout the surfaces of the leaves. A total of 42 isolates, 15 from initial, 15 from mature, and 12 from necrotic stages were isolated from the symptomatic leaf samples. Pestalotiopsis and Nigrospora were the two fungi incessantly isolated from the diseased leaves. Colony characteristics that included colony, hyphal, and spore morphologies were examined and mycelial accumulation, sporulation, and sporal germination were determined for all the isolates of Pestalotiopsis and Nigrospora. Molecular analysis based on ITS-RFLP was performed for identification and genetic variability. In vitro pathogenicity assay revealed that Pestalotiopsis spp. and Nigrospora sp. developed distinct characteristics symptoms on greenhouse acclimated TV17 tea clones. To our knowledge, this is the first report of the prevalence of tea blister blight disease in Meghalaya and it is an initial attempt to identify fungal pathogens during different stages of blister blight disease.

Localization of (+)-Catechin in Picea abies Phloem: Responses to Wounding and Fungal Inoculation.

To understand the positional and temporal defense mechanisms of coniferous tree bark at the tissue and cellular levels, the phloem topochemistry and structural properties were examined after artificially induced bark defense reactions. Wounding and fungal inoculation with Endoconidiophora polonica of spruce bark were carried out, and phloem tissues were frequently collected to follow the temporal and spatial progress of chemical and structural responses. The changes in (+)-catechin, (-)-epicatechin, stilbene glucoside, and resin acid distribution, and accumulation patterns within the phloem, were mapped using time-of-flight secondary ion mass spectrometry (cryo-ToF-SIMS), alongside detailed structural (LM, TEM, SEM) and quantitative chemical microanalyses of the tissues. Our results show that axial phloem parenchyma cells of Norway spruce contain (+)-catechins, the amount of which locally increases in response to fungal inoculation. The preformed, constitutive distribution and accumulation patterns of (+)-catechins closely follow those of stilbene glucosides. Phloem phenolics are not translocated but form a layered defense barrier with oleoresin compounds in response to pathogen attack. Our results suggest that axial phloem parenchyma cells are the primary location for (+)-catechin storage and synthesis in Norway spruce phloem. Chemical mapping of bark defensive metabolites by cryo-ToF-SIMS, in addition to structural and chemical microanalyses of the defense reactions, can provide novel information on the local amplitudes and localizations of chemical and structural defense mechanisms and pathogen-host interactions of trees.

Strepimidazoles A-G from the Plant Endophytic Streptomyces sp. PKU-EA00015 with Inhibitory Activities against a Plant Pathogenic Fungus.

Seven new 4-acyl-2-aminoimidazoles, designated strepimidazoles A-G (1-7), were discovered from the endophytic Streptomyces sp. PKU-EA00015 isolated from Salvia miltiorrhiza Bunge, whose dry root "Danshen" is one of the most widely used traditional Chinese medicines. The resonance signals of the 2-aminoimidazole moiety in 1-7 were absent in the NMR spectra due to tautomerization, and the structures of 1-7 were identified after preparation of their acetylation products 1a-7a, respectively. Compounds 1-7 represent a new family of 2-aminoimidazole-containing natural products, enriching the structural diversity of natural products from endophytic origin. Compounds 1-7 showed different degrees of inhibitory activities against the plant pathogenic fungus Verticillium dahliae V991, revealing structure-activity relationships on the acyl moieties. The plant pathogenic fungus V. dahliae has been confirmed to cause serious chlorosis of cultivated S. miltiorrhiza Bunge in China. This study opens the door for further investigation of mutualistic relationships between S. miltiorrhiza Bunge and their endophytic actinomycetes and for possible antifungal agent development for biological control of V. dahliae in the future.

MYB43 in Oilseed Rape (Brassica napus) Positively Regulates Vascular Lignification, Plant Morphology and Yield Potential but Negatively Affects Resistance to Sclerotinia sclerotiorum.

Arabidopsis thaliana MYB43 (AtMYB43) is suggested to be involved in cell wall lignification. PtrMYB152, the Populus orthologue of AtMYB43, is a transcriptional activator of lignin biosynthesis and vessel wall deposition. In this research, MYB43 genes from Brassica napus (rapeseed) and its parental species B. rapa and B. oleracea were molecularly characterized, which were dominantly expressed in stem and other vascular organs and showed responsiveness to Sclerotinia sclerotiorum infection. The BnMYB43 family was silenced by RNAi, and the transgenic rapeseed lines showed retardation in growth and development with smaller organs, reduced lodging resistance, fewer silique number and lower yield potential. The thickness of the xylem layer decreased by 28%; the numbers of sclerenchymatous cells, vessels, interfascicular fibers, sieve tubes and pith cells in the whole cross section of the stem decreased by 28%, 59%, 48%, 34% and 21% in these lines, respectively. The contents of cellulose and lignin decreased by 17.49% and 16.21% respectively, while the pectin content increased by 71.92% in stems of RNAi lines. When inoculated with S. sclerotiorum, the lesion length was drastically decreased by 52.10% in the stems of transgenic plants compared with WT, implying great increase in disease resistance. Correspondingly, changes in the gene expression patterns of lignin biosynthesis, cellulose biosynthesis, pectin biosynthesis, cell cycle, SA- and JA-signals, and defensive pathways were in accordance with above phenotypic modifications. These results show that BnMYB43, being a growth-defense trade-off participant, positively regulates vascular lignification, plant morphology and yield potential, but negatively affects resistance to S. sclerotiorum. Moreover, this lignification activator influences cell biogenesis of both lignified and non-lignified tissues of the whole vascular organ.

The deubiquitinating enzyme MoUbp8 is required for infection-related development, pathogenicity, and carbon catabolite repression in Magnaporthe oryzae.

Deubiquitination is an essential regulatory step in the Ub-dependent pathway. Deubiquitinating enzymes (DUBs) mediate the removal of ubiquitin moieties from substrate proteins, which are involved in many regulatory mechanisms. As a component of the DUB module (Ubp8/Sgf11/Sus1/Sgf73) in the SAGA (Spt-Ada-Gcn5-acetyltransferase) complex, Ubp8 plays a crucial role in both Saccharomyces cerevisiae and humans. In S. cerevisiae, Ubp8-mediated deubiquitination regulates transcriptional activation processes. To investigate the contributions of Ubp8 to physiological and pathological development of filamentous fungi, we generated the deletion mutant of ortholog MoUBP8 (MGG-03527) in Magnaporthe oryzae (syn. Pyricularia oryzae). The ΔMoubp8 strain showed reduced sporulation, pathogenicity, and resistance to distinct stresses. Even though the conidia of the ΔMoubp8 mutant were delayed in appressorium formation, the normal and abnormal (none-septum or one-septum) conidia could finally form appressoria. Reduced melanin in the ΔMoubp8 mutant is highly responsible for the attenuated pathogenicity since the appressoria of the ΔMoubp8 mutant was much more fragile than those of the wild type, due to the defective turgidity. The weakened ability to detoxify or scavenge host-derived reactive oxygen species (ROS) further restricted the invasion of the pathogen. We also showed that carbon derepression, on the one hand, rendered the ΔMoubp8 strain highly sensitive to allyl alcohol, on the other hand, it enhances the resistance of the MoUBP8 defective strain to deoxyglucose. Overall, we suggest that MoUbp8 is not only required for sporulation, melanin formation, appressoria development, and pathogenicity but also involved in carbon catabolite repression of M. oryzae.

Reynoutria sachalinensis extract elicits SA-dependent defense responses in courgette genotypes against powdery mildew caused by Podosphaera xanthii.

Powdery mildew (PM) caused by Podosphaera xanthii is one of the most important courgette diseases with high yield losses and is currently controlled by fungicides and sulphur applications in conventional and organic production. Plant derived elicitors/inducers of resistance are natural compounds that induce resistance to pathogen attack and promote a faster and/or more robust activation of plant defense responses. Giant knotweed (Reynoutria sachalinensis, RS) extract is a known elicitor of plant defenses but its mode of action remains elusive. The aim of this study was to investigate the mechanisms of foliar RS applications and how these affect PM severity and crop performance when used alone or in combination with genetic resistance. RS foliar treatments significantly reduced conidial germination and PM severity on both an intermediate resistance (IR) and a susceptible (S) genotype. RS application triggered plant defense responses, which induced the formation of callose papillae, hydrogen peroxide accumulation and the Salicylic acid (SA) - dependent pathway. Increased SA production was detected along with increased p-coumaric and caffeic acid concentrations. These findings clearly indicate that RS elicits plant defenses notably as a consequence of SA pathway induction.

Whole-genome and time-course dual RNA-Seq analyses reveal chronic pathogenicity-related gene dynamics in the ginseng rusty root rot pathogen Ilyonectria robusta.

Ilyonectria robusta causes rusty root rot, the most devastating chronic disease of ginseng. Here, we for the first time report the high-quality genome of the I. robusta strain CD-56. Time-course (36 h, 72 h, and 144 h) dual RNA-Seq analysis of the infection process was performed, and many genes, including candidate effectors, were found to be associated with the progression and success of infection. The gene expression profile of CD-56 showed a trend of initial inhibition and then gradually returned to a profile similar to that of the control. Analyses of the gene expression patterns and functions of pathogenicity-related genes, especially candidate effector genes, indicated that the stress response changed to an adaptive response during the infection process. For ginseng, gene expression patterns were highly related to physiological conditions. Specifically, the results showed that ginseng defenses were activated by CD-56 infection and persisted for at least 144 h thereafter but that the mechanisms invoked were not effective in preventing CD-56 growth. Moreover, CD-56 did not appear to fully suppress plant defenses, even in late stages after infection. Our results provide new insight into the chronic pathogenesis of CD-56 and the comprehensive and complex inducible defense responses of ginseng root to I. robusta infection.

Isobenzofuranone monomer and dimer derivatives from the mangrove endophytic fungus Epicoccum nigrum SCNU-F0002 possess α-glucosidase inhibitory and antioxidant activity.

Four new isobenzofuranone monomers, (+)-epicoccone C ((+)-1), (-)-epicoccone C ((-)-1), epicoccone D (2), epicoccone E (3) and one new isobenzofuranone dimer, epicolactone A (4), together with four known related dimers were obtained from the fermentation of an endophytic fungus, Epicoccum nigrum SCNU-F0002, which was isolated from the fresh fruit of the mangrove plant Acanthus ilicifolius L. Their structures were elucidated on the basis of spectroscopic methods, single-crystal X-ray diffraction analysis, and electronic circular dichroism calculations. These isolated compounds (1-8) were evaluated for their antioxidant activity and α-glucosidase enzyme inhibitory activity. All of the compounds except 5 exhibited more potent α-glucosidase inhibitory effect than acarbose. Most of the compounds showed superior antioxidant activity with IC50 values ranging from 10.2 to 15.3 µM than positive control, gallic acid and vitamin C.