Antifungal Activity of Menisporopsin A against Relevant Plant Pathogens.

Current agrochemicals used in crop farming mainly consist of synthetic compounds with harmful effects on the environment and human health. Crop-associated fungal endophytes, which play many ecological roles including defense against pathogens, represent a promising source for bioactive and ecologically safer molecules in agrochemical discovery. The methanolic extract of the endophyte Menisporopsis sp. LCM 1078 was evaluated in vitro against the plant pathogens Boeremia exigua, Calonectria variabilis, Colletotrichum theobromicola, Colletotrichum tropicale, and Mycena cytricolor. Bioassay-guided isolation using chromatographic techniques followed by detailed chemical characterization by NMR and mass spectrometry led to the identification of menisporopsin A, which showed inhibitory activity in a dose-dependent manner against the five fungal pathogens including an endophytic strain (Colletotrichum tropicale), with MIC values in the range of 0.63-10.0 µg/mL showing a potency equivalent to the broadly employed agrochemical mancozeb.

Role of Volatile Organic Compounds Produced by Kosakonia cowanii Cp1 during Competitive Colonization Interaction against Pectobacterium aroidearum SM2.

The competitive colonization of bacteria on similar ecological niches has a significant impact during their establishment. The synthesis speeds of different chemical classes of molecules during early competitive colonization can reduce the number of competitors through metabolic effects. In this work, we demonstrate for the first time that Kosakonia cowanii Cp1 previously isolated from the seeds of Capsicum pubescens R. P. produced volatile organic compounds (VOCs) during competitive colonization against Pectobacterium aroidearum SM2, affecting soft rot symptoms in serrano chili (Capsicum annuum L.). The pathogen P. aroidearum SM2 was isolated from the fruits of C. annuum var. Serrano with soft rot symptoms. The genome of the SM2 strain carries a 5,037,920 bp chromosome with 51.46% G + C content and 4925 predicted protein-coding genes. It presents 12 genes encoding plant-cell-wall-degrading enzymes (PCDEWs), 139 genes involved in five types of secretion systems, and 16 genes related to invasion motility. Pathogenic essays showed soft rot symptoms in the fruits of C. annuum L., Solanum lycopersicum, and Physalis philadelphica and the tubers of Solanum tuberosum. During the growth phases of K. cowanii Cp1, a mix of VOCs was identified by means of HS-SPME-GC-MS. Of these compounds, 2,5-dimethyl-pyrazine showed bactericidal effects and synergy with acetoin during the competitive colonization of K. cowanii Cp1 to completely reduce soft rot symptoms. This work provides novel evidence grounding a better understanding of bacterial interactions during competitive colonization on plant tissue, where VOC synthesis is essential and has a high potential capacity to control pathogenic microorganisms in agricultural systems.

Multiple horizontal gene transfer events have shaped plant glycosyl hydrolase diversity and function.

Plant glycosyl hydrolases (GHs) play a crucial role in selectively breaking down carbohydrates and glycoconjugates during various cellular processes, such as reserve mobilization, pathogen defense, and modification/disassembly of the cell wall. In this study, we examined the distribution of GH genes in the Archaeplastida supergroup, which encompasses red algae, glaucophytes, and green plants. We identified that the GH repertoire expanded from a few tens of genes in early archaeplastidians to over 400 genes in modern angiosperms, spanning 40 GH families in land plants. Our findings reveal that major evolutionary transitions were accompanied by significant changes in the GH repertoire. Specifically, we identified at least 23 GH families acquired by green plants through multiple horizontal gene transfer events, primarily from bacteria and fungi. We found a significant shift in the subcellular localization of GH activity during green plant evolution, with a marked increase in extracellular-targeted GH proteins associated with the diversification of plant cell wall polysaccharides and defense mechanisms against pathogens. In conclusion, our study sheds light on the macroevolutionary processes that have shaped the GH repertoire in plants, highlighting the acquisition of GH families through horizontal transfer and the role of GHs in plant adaptation and defense mechanisms.

Genome-wide survey and evolutionary history of the pectin methylesterase (PME) gene family in the Dothideomycetes class of fungi.

Once deposited in the plant cell wall, pectin undergoes demethylesterification by endogenous pectin methylesterases (PMEs), which play various roles in growth and development, including defense against pathogen attacks. Pathogen PMEs can alter pectin's methylesterification pattern, increasing its susceptibility to degradation by other fungal pectinases and thus playing a critical role as virulence factors during early infection stages. To investigate the evolutionary history of PMEs in the Dothideomycetes class of fungi, we obtained genomic data from 15 orders (79 species) and added genomic data from 61 isolates of Corynespora cassiicola. Our analyses involved maximum likelihood phylogenies, gene genealogies, and selection analyses. Additionally, we measured PME gene expression levels of C. cassiicola using soybean as a host through RT-qPCR assays. We recovered 145 putative effector PMEs and 57 putative non-effector PMEs from across the Dothideomycetes. The PME gene family exhibits a small size (up to 5 members per genome) and comprises three major clades. The evolutionary patterns of the PME1 and PME2 clades were largely shaped by duplications and recurring gene retention events, while biased gene loss characterized the small-sized PME3 clade. The presence of five members in the PME gene family of C. cassiicola suggests that the family may play a key role in the evolutionary success of C. cassiicola as a polyphagous plant pathogen. The haplogroups Cc_PME1.1 and Cc_PME1.2 exhibited an accelerated rate of evolution, whereas Cc_PME2.1, Cc_PME2.2, and Cc_PME2.3 seem to be under strong purifying selective constraints. All five PME genes were expressed during infection of soybean leaves, with the highest levels during from six to eight days post-inoculation. The highest relative expression level was measured for CC_29_g7533, a member of the Cc_PME2.3 clade, while the remaining four genes had relatively lower levels of expression.

Target and non-target site mechanisms of fungicide resistance and their implications for the management of crop pathogens.

Fungicides are indispensable for high-quality crops, but the rapid emergence and evolution of fungicide resistance have become the most important issues in modern agriculture. Hence, the sustainability and profitability of agricultural production have been challenged due to the limited number of fungicide chemical classes. Resistance to site-specific fungicides has principally been linked to target and non-target site mechanisms. These mechanisms change the structure or expression level, affecting fungicide efficacy and resulting in different and varying resistance levels. This review provides background information about fungicide resistance mechanisms and their implications for developing anti-resistance strategies in plant pathogens. Here, our purpose was to review changes at the target and non-target sites of quinone outside inhibitor (QoI) fungicides, methyl-benzimidazole carbamate (MBC) fungicides, demethylation inhibitor (DMI) fungicides, and succinate dehydrogenase inhibitor (SDHI) fungicides and to evaluate if they may also be associated with a fitness cost on crop pathogen populations. The current knowledge suggests that understanding fungicide resistance mechanisms can facilitate resistance monitoring and assist in developing anti-resistance strategies and new fungicide molecules to help solve this issue. © 2023 Society of Chemical Industry.

Graphene-Cu Nanocomposites Induce Tolerance against Fusarium oxysporum, Increase Antioxidant Activity, and Decrease Stress in Tomato Plants.

The tomato crop is susceptible to various types of stress, both biotic and abiotic, which affect the morphology, physiology, biochemistry, and genetic regulation of plants. Among the biotic factors, is the phytopathogen Fusarium oxysporum f. sp. lycopersici (Fol), which can cause losses of up to 100%. Graphene-Cu nanocomposites have emerged as a potential alternative for pathogen control, thanks to their antimicrobial activity and their ability to induce the activation of the antioxidant defense system in plants. In the present study, the effect of the Graphene-Cu nanocomposites and the functionalization of graphene in the tomato crop inoculated with Fol was evaluated, analyzing their impacts on the antioxidant defense system, the foliar water potential (Ψh), and the efficiency of photosystem II (PSII). The results demonstrated multiple positive effects; in particular, the Graphene-Cu nanocomposite managed to delay the incidence of the "vascular wilt" disease and reduce the severity by 29.0%. This translated into an increase in the content of photosynthetic pigments and an increase in fruit production compared with Fol. In addition, the antioxidant system of the plants was improved, increasing the content of glutathione, flavonoids, and anthocyanins, and the activity of the GPX, PAL, and CAT enzymes. Regarding the impact on the water potential and the efficiency of the PSII, the plants inoculated with Fol and treated with the Graphene-Cu nanocomposite responded better to biotic stress compared with Fol, reducing water potential by up to 31.7% and Fv/Fm levels by 32.0%.

Distribution of Dalbulus maidis (DeLong) (Hemiptera: Cicadellidae) and incidence of maize rayado fino virus and Candidatus Phytoplasma asteris in corn succession planting systems.

BACKGROUND: Corn is one of the main crops grown globally to produce food for human consumption and animal feed, including raw materials for bioenergy. Effective pest management is critical for the economic viability of corn production. The leafhopper Dalbulus maidis and the diseases transmitted by it have become relevant to corn production. Our study aimed to determine environmental parameters that affect D. maidis populations and the impacts of pathogen dispersion on corn productivity under different rotation systems and sowing seasons. RESULTS: The population density of leafhoppers found in the studied crops was low but capable of establishing the diseases and spreading them widely in the crops. The leafhopper's highest occurrence was in the corn vegetative development stage, and its population peaks were earlier in the corn off-season. The incidence of maize rayado fino virus and maize bushy stunt phytoplasma were higher in corn off-season than in the growing season. The incidence of diseases was higher in the final stages of the cultivation cycle. Yield losses were significantly higher for maize bushy stunt phytoplasma and not significant for maize rayado fino virus. CONCLUSION: Our study observed that corn's physiological stage was the main factor influencing D. maidis dynamics. The occurrence of D. maidis at low densities was sufficient to ensure the efficient transmission and dissemination of maize rayado fino virus and maize bushy stunt phytoplasma, which had a higher incidence in the reproductive stage and the corn sowed off-season. © 2023 Society of Chemical Industry.

Mexico: A Landscape of Viroid Origin and Epidemiological Relevance of Endemic Species.

Viroids are single-stranded, circular RNA molecules (234-406 nt) that infect a wide range of crop species and cause economic losses in agriculture worldwide. They are characterized by the existence of a population of sequence variants, attributed to the low fidelity of RNA polymerases involved in their transcription, resulting in high mutation rates. Therefore, these biological entities exist as quasispecies. This feature allows them to replicate within a wide range of host plants, both monocots and dicots. Viroid hosts include economically important crops such as tomato, citrus, and fruit trees such as peach and avocado. Given the high risk of introducing viroids to viroid disease-free countries, these pathogens have been quarantined globally. As discussed herein, Mexico represents a geographical landscape of viroids linked to their origin and comprises considerable biodiversity. The biological features of viroid species endemic to Mexico are highlighted in this communication. In addition, we report the phylogenetic relationships among viroid and viroid strains, their economic impact, geographical distribution, and epidemiological features, including a broad host range and possible long-distance, seed, or insect-mediated transmission. In summary, this review could be helpful for a better understanding of the biology of viroid diseases and future programs on control of movement and spread to avoid economic losses in agricultural industries.

Characterization of physiological and antioxidant responses in Run1Ren1 Vitis vinifera plants during Erysiphe necator attack.

Grapevine is a fruit crop of major significance worldwide. Fungal attacks are one of the most relevant factors affecting grapevine yield and fruit quality, and powdery mildew caused by Erysiphe necator is one of the most harmful fungal diseases for this fruit-bearing species. Incorporating resistance genes such as Run1 and Ren1 in new vine selections offers a sustainable alternative to control the disease. These combined loci produce an immune response that prevents the development of the disease. However, to date studies are lacking concerning whether this response generates alterations in the physiological and antioxidant parameters of resistant plants in the presence of the fungus or if it has an associated energy cost. Therefore, the main goal of our research was to determine if Run1Ren1 plants present alterations in their physiological and biochemical parameters in the presence of the fungus. To achieve this target, a previously characterized resistant Run1Ren1 genotype and the susceptible Carménère cultivar were analyzed. We evaluated photochemical parameters (Fv'/Fm', ΦPSII and ETR), net photosynthesis (Pn), photosynthetic pigments, transpiration (E), stomatal conductance (gs ), oxidative stress parameters (MDA), antioxidant activity, and phenols. Our results show that the physiological parameters of Run1Ren1 plants were not negatively affected by the fungus at 10 days post-inoculation, contrasting with alterations observed in the susceptible plants. Therefore, we propose that the resistance response triggered by Run1Ren1 is physiologically and biochemically advantageous to grapevines by preventing the development of powdery mildew infection.

Cucurbit Powdery Mildew: First Insights for the Identification of the Causal Agent and Screening for Resistance of Squash Genotypes (Cucurbita moschata (Duchesne ex Lam.) Duchesne ex Poir.) in Mendoza, Argentina.

The cucurbit powdery mildew (CPM) caused by different fungal species is a major concern for cucurbit crops around the world. In Argentina CPM constitutes the most common and damaging disease for cucurbits, especially for squash crops (Cucurbita moschata). The present study displays initial insights into the knowledge of the disease in western Argentina, including the determination of the prevalent species causing CPM, as well as the evaluation of the resistance of squash cultivars and breeding lines. Fungal colonies were isolated from samples collected in Mendoza province, Argentina. A field trial was also performed to assess the resistance of five squash accessions, including commercial cultivars and breeding lines. The severity of CPM was analyzed and epidemiological models were built based on empirical data. The morphological determinations and analysis with specific molecular markers confirmed Podosphaera xanthi as the prevalent causal agent of CPM in Mendoza. The results od the field trial showed differences in the resistance trait among the squash accessions. The advanced breeding line BL717/1 showed promising results as source of CPM resistance for the future development of open pollinated resistant cultivars, a crucial tool for an integrative control of the disease.

Efficiency of different strains of Trichoderma on the control of Sclerotinia sclerotiorum, Sclerotium rolfsii and Sclerotium cepivorum

The aim of this work was to verify the efficiency of different isolates of Trichoderma spp.on the control of Sclerotiniasclerotiorum, Sclerotiumrolfsii and Sclerotiumcepivorum, and the influence they pose on the conidia production of Trichoderma spp.For mycelial growth, discs with inoculum of phytopathogens were placed on the center of the Petri dishes followed by the addition of two Trichodermasp. discs on the opposite sides of the plate after 24hours. Every 12hoursdata were collected from colonies diameters and used for the analyses of Mycelial Growth Index (MGI) and Area Under the Curve of Mycelial Growth (AUCMG). The analyses were performed by a completely randomized design with two controls, a negative one without Trichodermasp. and one with acommercial strain of Trichodermaharzianum. Spore solution for evaluation of conidia production were made by adding 10 mL of distilled water and scratching the surface of the colonies. For S. cepivorum, all Trichoderma spp. strains reduced both indexes tested. However, while for MGI S. sclerotiorum also presented some reduction on the growth rate, the total area of this fungus was not affected. Sclerotiumrolfsii strains of Trichodermasp. from Lages and Curitibanosshowed an effect on the reduction of AUCMG of this fungus, although none of the Trichodermaaffected the growth rate of this phytopathogen. On the presence of S. sclerotiorumand S. cepivorum, none of the Trichodermaspp. showed any difference on conidia production when compared among themselves, nonetheless we did notice that on the presence of S. cepivorum, the strain from Rio do Sul retained its reproductive ability compared to control. Results obtained from this research can demonstrate the importance of biocontrol agents against different plant pathogens since it might have a specific antagonist-pathogen relation.(AU)

First report of Cercospora cf. malloti causing brown eyespot on strawberry in Brazil.

Strawberry (Fragaria x ananassa Duch.) is one of the most consumed fruits from the Rosaceae family in Brazil. It is cultivated on ~4,500 ha in all regions of the country, with a wide range of fungi causing leaf diseases. Strawberry leaves (cv. San Andreas) with symptoms of eyespot usually related to Mycosphaerella fragariae (Ramularia tulasnei) (Mazaro et al. 2006) were observed in April 2019, in a field located in Santa Maria, Rio Grande do Sul state, Brazil (29°43'19.6"S / 53°43'04.6"W). However, the symptoms slightly differed from Mycospherella blight as well as the fungi structures observed under an optical microscope. The symptomatic leaves had small circular spots, initially reddish-purple to dark brown color, which later increased in size. The center of the lesion was grayish pale, where dark brown conidiophores were found over it. The symptom occurred in 50% of the leaves of all plants during the crop season. To identify the causal agent, symptomatic leaves were collected and superficially disinfected with 70% ethanol for 30 s followed by 0.5% bleach for 30 s and then washed in sterile water. The leaves were placed in germination boxes with a moistened paper filter and incubated at 25 ºC and 12 h photoperiod for four days. After the formation of the fungal structures, the fungi was isolated in potato dextrose agar (PDA) medium and kept for 20 days at 25 ºC. Colonies were dark brown with pale pink aerial mycelium. The conidia were hyaline, single- to multi-septated with a filiform shape, straight or slightly curved. The fasciculate conidiophores on the stroma measured 20 to 70 x 2.5 to 3.5 µm. Conidia average measurement was 10.2 to 82.4 x 4. to 8.8 µm, similar to morphological characteristics of the genus Cercospora. The isolate named M6 was deposited in the Brazilian National System of Genetic Registration (SISGEN) no A57AE19. The DNA was extracted from a monosporic culture of M6 in PDA plates, which presented all typical aspects previously described. To confirm the identity, the PCR amplification was carried out for internal transcribed spacer (ITS) region ITS 1-5.8S - ITS 2 and Calmodulin region (CAL) genes (Acqua et al, 2011). The ITS (No. MZ713249) and CAL (No. MZ713254) sequences were deposited in the Genbank database. BLASTn analysis revealed the isolate was 99% similar to Cercospora cf. malloti which access codes in GenBank are KT 193689 and KT 193738 (Nguanhom et al. 2015). A pathogenicity test was performed to fulfill Koch's postulates. Strawberry plants with healthy leaves (60 days old), were inoculated by spraying a conidial suspension (1 × 105 conidia/ml). Control plants were sprayed with sterile water. The plants were incubated in a greenhouse at 28 ºC for 12 h photoperiod at 80% relative humidity under drip irrigation keeping at least 60% of field capacity. Six plants were used as replicates. Twenty days after inoculation, small circular reddish-purple spots were found, which later increased in size. Ten days later, the spots presented dark brown conidiophores over the center of the lesion. The symptoms described above were observed in all inoculated leaves. The control plants remained symptom-free. The pathogen was then re-isolated from the lesions and identified as C. cf. malloti based on the morphological aspects described above on PDA. In Thailand C. cf. malloti is reported on crops like Brassica alboglabra (cabbage) (Nguanhom et al. 2015), but not in strawberries. To our knowledge, this is the first report of C. cf. malloti pathogenic to strawberries in Brazil.

Evaluation of Tarsonemus bilobatus and Podosphaera xanthii as suitable resources for Proprioseiopsis mexicanus in cucurbit systems in the Southeast USA.

Tritrophic relationships involving tarsonemids and predatory phytoseiids are common in a variety of agroecosystems, but due to the wide range of diets in both families, it is necessary to understand what food resources they are consuming to determine potential impact on crops. We investigated a frequent association of cucurbit powdery mildew (Podosphaera xanthii), Tarsonemus bilobatus, and Proprioseiopsis mexicanus in watermelon and pumpkin fields to determine whether P. mexicanus is consuming either or both of the other organisms. We also examined developmental and reproductive capability of P. mexicanus on these diets. If P. mexicanus is an effective predator of T. bilobatus, it may also be useful in controlling pest tarsonemids, such as broad mites. Proprioseiopsis mexicanus either starved or escaped from arenas rather than consume P. xanthii. When consuming T. bilobatus, P. mexicanus females developed from larva to adult in ca. 3 days. On this diet, the preoviposition period was ca. 2 days and P. mexicanus laid 1.7 eggs/day. These results are comparable to some of the higher-quality non-prey resources investigated in the literature. Starved female P. mexicanus consumed 6.5 T. bilobatus of mixed stages in 1 h. This study provides support for further research into the importance of non-pest tarsonemids as a resource to maintain the presence of generalist predatory mites as an early-intervention natural enemy. Further work should examine the efficacy of P. mexicanus as a natural enemy of economically important pest tarsonemids.

Trichoderma as biological control agent: scope and prospects to improve efficacy.

A major current challenge is to increase the food production while preserving natural resources. Agricultural practices that enhance the productivity and progressively improve the soil quality are relevant to face this challenge. Trichoderma species are widely used in agriculture to stimulate the plant growth and to control different pathogens affecting crops, representing useful tools for sustainable food production. This mini-review summarizes applications of Trichoderma strains in agriculture to control fungal pathogens, nematodes and insects, the involved biocontrol mechanisms, efficacy and inoculation forms in greenhouse, field and post-harvest conditions. Aspects of Trichoderma handling that influence on biocontrol efficacy such as preventive treatments, frequency of applications and delivery methods are discussed. Strategies useful to improve the antagonistic performance such as the use of native strains, protoplast fusion, formulation, growth on pathogen cell wall medium and combination with other antagonists in integrated treatments are discussed. This mini-review provides practical knowledge to design safe and optimal biocontrol strategies based on Trichoderma and pose challenges to expand its antagonist performance.

The Mitochondrial Genome of a Plant Fungal Pathogen Pseudocercospora fijiensis (Mycosphaerellaceae), Comparative Analysis and Diversification Times of the Sigatoka Disease Complex Using Fossil Calibrated Phylogenies.

Mycosphaerellaceae is a highly diverse fungal family containing a variety of pathogens affecting many economically important crops. Mitochondria play a crucial role in fungal metabolism and in the study of fungal evolution. This study aims to: (i) describe the mitochondrial genome of Pseudocercospora fijiensis, and (ii) compare it with closely related species (Sphaerulina musiva, S. populicola, P. musae and P. eumusae) available online, paying particular attention to the Sigatoka disease's complex causal agents. The mitochondrial genome of P. fijiensis is a circular molecule of 74,089 bp containing typical genes coding for the 14 proteins related to oxidative phosphorylation, 2 rRNA genes and a set of 38 tRNAs. P. fijiensis mitogenome has two truncated cox1 copies, and bicistronic transcription of nad2-nad3 and atp6-atp8 confirmed experimentally. Comparative analysis revealed high variability in size and gene order among selected Mycosphaerellaceae mitogenomes likely to be due to rearrangements caused by mobile intron invasion. Using fossil calibrated Bayesian phylogenies, we found later diversification times for Mycosphaerellaceae (66.6 MYA) and the Sigatoka disease complex causal agents, compared to previous strict molecular clock studies. An early divergent Pseudocercospora fijiensis split from the sister species P. musae + P. eumusae 13.31 MYA while their sister group, the sister species P. eumusae and P. musae, split from their shared common ancestor in the late Miocene 8.22 MYA. This newly dated phylogeny suggests that species belonging to the Sigatoka disease complex originated after wild relatives of domesticated bananas (section Eumusae; 27.9 MYA). During this time frame, mitochondrial genomes expanded significantly, possibly due to invasions of introns into different electron transport chain genes.

Plant-mediated synthesis of nanoparticles and their antimicrobial activity against phytopathogens.

Nanotechnology is an emerging science with a wide array of applications involving the synthesis and manipulation of materials with dimensions in the range of 1-100 nm. Nanotechnological applications include diverse fields such as pharmaceuticals, medicine, the environment, food processing and agriculture. Regarding the latter, applications are mainly focused on plant growth and crop protection against plagues and diseases. In recent years, the biogenic reduction of elements such as Ag, Au, Cu, Cd, Al, Se, Zn, Ce, Ti and Fe with plant extracts has become one of the most accepted techniques for obtaining nanoparticles (NPs), as it is considered an ecological and cost-effective process without the use of chemical contaminants. The objective of this work was to review NPs synthesized by green chemistry using vegetable extracts, as well as their use as antimicrobial agents against phytopathogenic fungi and bacteria. Given the need for alternatives to control and integrate management of phytopathogens, this review is relevant to agriculture, although this technology is barely exploited in this field. © 2020 Society of Chemical Industry.

Fumonisin and Beauvericin Chemotypes and Genotypes of the Sister Species Fusarium subglutinans and Fusarium temperatum.

Fusarium subglutinans and Fusarium temperatum are common maize pathogens that produce mycotoxins and cause plant disease. The ability of these species to produce beauvericin and fumonisin mycotoxins is not settled, as reports of toxin production are not concordant. Our objective was to clarify this situation by determining both the chemotypes and genotypes for strains from both species. We analyzed 25 strains from Argentina, 13 F. subglutinans and 12 F. temperatum strains, for toxin production by ultraperformance liquid chromatography mass spectrometry (UPLC-MS). We used new genome sequences from two strains of F. subglutinans and one strain of F. temperatum, plus genomes of other Fusarium species, to determine the presence of functional gene clusters for the synthesis of these toxins. None of the strains examined from either species produced fumonisins. These strains also lack Fum biosynthetic genes but retain homologs of some genes that flank the Fum cluster in Fusarium verticillioides None of the F. subglutinans strains we examined produced beauvericin although 9 of 12 F. temperatum strains did. A complete beauvericin (Bea) gene cluster was present in all three new genome sequences. The Bea1 gene was presumably functional in F. temperatum but was not functional in F. subglutinans due to a large insertion and multiple mutations that resulted in premature stop codons. The accumulation of only a few mutations expected to disrupt Bea1 suggests that the process of its inactivation is relatively recent. Thus, none of the strains of F. subglutinans or F. temperatum we examined produce fumonisins, and the strains of F. subglutinans examined also cannot produce beauvericin. Variation in the ability of strains of F. temperatum to produce beauvericin requires further study and could reflect the recent shared ancestry of these two species.IMPORTANCEFusarium subglutinans and F. temperatum are sister species and maize pathogens commonly isolated worldwide that can produce several mycotoxins and cause seedling disease, stalk rot, and ear rot. The ability of these species to produce beauvericin and fumonisin mycotoxins is not settled, as reports of toxin production are not concordant at the species level. Our results are consistent with previous reports that strains of F. subglutinans produce neither fumonisins nor beauvericin. The status of toxin production by F. temperatum needs further work. Our strains of F. temperatum did not produce fumonisins, while some strains produced beauvericin and others did not. These results enable more accurate risk assessments of potential mycotoxin contamination if strains of these species are present. The nature of the genetic inactivation of BEA1 is consistent with its relatively recent occurrence and the close phylogenetic relationship of the two sister species.

Genomic Insights Into the Antifungal Activity and Plant Growth-Promoting Ability in Bacillus velezensis CMRP 4490.

The main objective of this study was to evaluate Bacillus velezensis strain CMRP 4490 regarding its ability to inhibit soil-borne plant pathogens and to increase plant growth. The study included evaluation of in vitro antifungal control, sequencing the bacterial genome, mining genes responsible for the synthesis of secondary metabolites, root colonization ability, and greenhouse studies for the assessment of plant growth-promoting ability. The strain was obtained from soil samples in the north of Paraná in Brazil and was classified as a B. velezensis, which is considered a promising biological control agent. In vitro assay showed that B. velezensis CMRP 4490 presented antagonistic activity against Sclerotinia sclerotiorum, Macrophomina phaseolina, Botrytis cinerea, and Rhizoctonia solani with a mycelial growth inhibition of approximately 60%, without any significant difference among them. To well understand this strain and to validate its effect on growth-promoting rhizobacteria, it was decided to explore its genetic content through genome sequencing, in vitro, and greenhouse studies. The genome of CMRP 4490 was estimated at 3,996,396 bp with a GC content of 46.4% and presents 4,042 coding DNA sequences. Biosynthetic gene clusters related to the synthesis of molecules with antifungal activity were found in the genome. Genes linked to the regulation/formation of biofilms, motility, and important properties for rhizospheric colonization were also found in the genome. Application of CMRP 4490 as a coating film on soybean increased from 55.5 to 64% on germination rates when compared to the control; no differences were observed among treatments for the maize germination. The results indicated that B. velezensis CMRP 4490 could be a potential biocontrol agent with plant growth-promoting ability.

Comparative genomics of Paraburkholderia kururiensis and its potential in bioremediation, biofertilization, and biocontrol of plant pathogens.

Burkholderia harbors versatile Gram-negative species and is ß-Proteobacteria. Recently, it was proposed to split the genus in two main branches: one of animal and plant pathogens and another, Paraburkholderia, harboring environmental and plant-beneficial species. Currently, Paraburkholderia comprises more than 70 species with ability to occupy very diverse environmental niches. Herein, we sequenced and analyzed the genome of Paraburkholderia kururiensis type strain KP23T , and compared to P. kururiensis M130, isolated in Brazil, and P. kururiensis susbp. thiooxydans, from Korea. This study focused on the gene content of the three genomes with special emphasis on their potential of plant-association, biocontrol, and bioremediation. The comparative analyses revealed several genes related to plant benefits, including biosynthesis of IAA, ACC deaminase, multiple efflux pumps, dioxygenases, and degradation of aromatic compounds. Importantly, a range of genes for protein secretion systems (type III, IV, V, and VI) were characterized, potentially involved in P. kururiensis well documented ability to establish endophytic association with plants. These findings shed light onto bacteria-plant interaction mechanisms at molecular level, adding novel information that supports their potential application in bioremediation, biofertilization, and biocontrol of plant pathogens. P. kururiensis emerges as a promising model to investigate adaptation mechanisms in different ecological niches.

Genome sequence and effectorome of Moniliophthora perniciosa and Moniliophthora roreri subpopulations.

BACKGROUND: The hemibiotrophic pathogens Moniliophthora perniciosa (witches' broom disease) and Moniliophthora roreri (frosty pod rot disease) are among the most important pathogens of cacao. Moniliophthora perniciosa has a broad host range and infects a variety of meristematic tissues in cacao plants, whereas M. roreri infects only pods of Theobroma and Herrania genera. Comparative pathogenomics of these fungi is essential to understand Moniliophthora infection strategies, therefore the detection and in silico functional characterization of effector candidates are important steps to gain insight on their pathogenicity. RESULTS: Candidate secreted effector proteins repertoire were predicted using the genomes of five representative isolates of M. perniciosa subpopulations (three from cacao and two from solanaceous hosts), and one representative isolate of M. roreri from Peru. Many putative effectors candidates were identified in M. perniciosa: 157 and 134 in cacao isolates from Bahia, Brazil; 109 in cacao isolate from Ecuador, 92 and 80 in wild solanaceous isolates from Minas Gerais (Lobeira) and Bahia (Caiçara), Brazil; respectively. Moniliophthora roreri showed the highest number of effector candidates, a total of 243. A set of eight core effectors were shared among all Moniliophthora isolates, while others were shared either between the wild solanaceous isolates or among cacao isolates. Mostly, candidate effectors of M. perniciosa were shared among the isolates, whereas in M. roreri nearly 50% were exclusive to the specie. In addition, a large number of cell wall-degrading enzymes characteristic of hemibiotrophic fungi were found. From these, we highlighted the proteins involved in cell wall modification, an enzymatic arsenal that allows the plant pathogens to inhabit environments with oxidative stress, which promotes degradation of plant compounds and facilitates infection. CONCLUSIONS: The present work reports six genomes and provides a database of the putative effectorome of Moniliophthora, a first step towards the understanding of the functional basis of fungal pathogenicity.