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Plants interact with a great diversity of microorganisms or insects throughout their life cycle in the environment. Plant and insect interactions are common; besides, a great variety of microorganisms associated with insects can induce pathogenic damage in the host, as mutualist phytopathogenic fungus. However, there are other microorganisms present in the insect-fungal association, whose biological/ecological activities and functions during plant interaction are unknown. In the present work evaluated, the role of microorganisms associated with Xyleborus affinis, an important beetle species within the Xyleborini tribe, is characterized by attacking many plant species, some of which are of agricultural and forestry importance. We isolated six strains of microorganisms associated with X. affinis shown as plant growth-promoting activity and altered the root system architecture independent of auxin-signaling pathway in Arabidopsis seedlings and antifungal activity against the phytopathogenic fungus Fusarium sp. INECOL_BM-06. In addition, evaluating the tripartite interaction plant-microorganism-fungus, interestingly, we found that microorganisms can induce protection against the phytopathogenic fungus Fusarium sp. INECOL_BM-06 involving the jasmonic acid-signaling pathway and independent of salicylic acid-signaling pathway. Our results showed the important role of this microorganisms during the plant- and insect-microorganism interactions, and the biological potential use of these microorganisms as novel agents of biological control in the crops of agricultural and forestry is important.

Fusarium kuroshium is the fungal symbiont associated with the ambrosia beetle Euwallacea kuroshio, a plague complex that attacks avocado, among other hosts, causing a disease named Fusarium dieback (FD). However, the contribution of F. kuroshium to the establishment of this disease remains unknown. To advance the understanding of F. kuroshium pathogenicity, we profiled its exo-metabolome through metabolomics tools based on accurate mass spectrometry. We found that F. kuroshium can produce several key metabolites with phytotoxicity properties and other compounds with unknown functions. Among the metabolites identified in the fungal exo-metabolome, fusaric acid (FA) was further studied due to its phytotoxicity and relevance as a virulence factor. We tested both FA and organic extracts from F. kuroshium at various dilutions in avocado foliar tissue and found that they caused necrosis and chlorosis, resembling symptoms similar to those observed in FD. This study reports for first-time insights regarding F. kuroshium associated with its virulence, which could lead to the potential development of diagnostic and management tools of FD disease and provides a basis for understanding the interaction of F. kuroshium with its host plants.

Background: Neofusicoccum parvum belongs to the Botryosphaeriaceae family, which groups endophytic and latent pathogens of woody plants responsible for diseases such as cankers, dieback and blight. It is a widespread pathogen with a broad host range, including agricultural, horticultural and forestry plants; therefore, it is relevant to characterize the molecular mechanisms involved in the disease caused by this pathogen. This work reports for the first time N. parvum as a pathogen of Liquidambar styraciflua. We established an in vitro pathosystem using foliar tissue to characterize the infection process through scanning electron microscopy (SEM). Because cysteine-rich proteins (CysRPs) have been studied for their important functions in plant-pathogen interactions, new CysRPs were identified for these organisms, and mRNA expression of these proteins was analyzed at early time points during the interaction.Results: After the first 24 hours post infection, the pathogen caused visible symptoms, and microscopic analysis at 16 days post infection revealed the presence of N. parvum pycnidia embedded in L. styraciflua leaf tissue. For both organisms, two databases with transcriptomic and genomic information were analyzed, and five new CysRPs were identified for each organism. The length varied between 95 and 204 amino acids, and in silico analysis revealed that all the proteins are potentially secreted. The search for conserved domains and phylogenetic analyses revealed that all the proteins are novel, including two of N. parvum that present the well-known CFEM domain. RT-qPCR analysis was conducted at 24 and 72 hours post infection, and the results showed changes in the levels of CysRP mRNAs for both the plant and the fungus at early stages during the interaction.Conclusions: N. parvum was identified for the first time as a pathogen of L. styraciflua, and this work presents an approach to comprehensively understand the molecular mechanisms involved in this interaction, highlighting the potential involvement of CysRPs of both organisms under this biotic stress.

Background Neofusicoccum parvum belongs to Botryosphaeriaceae family that groups endophytic and latent pathogens of woody plants responsible of diseases such as cankers, dieback and blight. Is a widespread pathogen in a broad host range including agricultural, horticultural and forestry plants, therefore is relevant to characterize molecular mechanisms involved in the disease. This work, report for first time a N. parvum as a pathogen of Liquidambar styraciflua. We established an in vitro pathosystem using foliar tissue in order to characterize the infection process through scanning electron microscopy. Because cysteine rich proteins (CysRPs) are well described for their important functions under plant-pathogen interaction, new CysRPs were identified for these organisms, and mRNAs expression of these proteins was analyzed at early times during the interaction.Results Since the first 24 hours post infection, the pathogen caused visible symptoms and the microscopic analysis at 16 days post infection revealed the presence of N. parvum pycnidium immersed in L. styraciflua leaf tissue. For both organisms, two databases with transcriptomic and genomic information were analyzed and new five CysRPs were identified for each organism, the amino acid length varied between 95 and 204 and in silico analysis revealed that all proteins are potentially secreted. The search of conserved domains and phylogenetic analyses bring to light that all proteins are novel including two of N. parvum that present the well-known CFEM domain. RT-qPCR analysis was conducted at 24- and 72-hours post infection and the results showed change levels of CysRPs mRNAs for both the plant and the fungus at early times during the interaction.ConclusionsIt is recognized for first time that N. parvum is a pathogen of L. styraciflua and this work represents an approach to begin to deeply understand the molecular mechanisms involved in this interaction highlighting the potential involvement of CysRPs of both organism during this biotic stress.

Neofusicoccum parvum belongs to the Botryosphaeriaceae family, which contains endophytes and pathogens of woody plants. In this study, we isolated 11 strains from diseased tissue of Liquidambar styraciflua. Testing with Koch’s postulates—followed by a molecular approach—revealed that N. parvum was the most pathogenic strain. We established an in vitro pathosystem (L. styraciflua foliar tissue–N. parvum) in order to characterize the infection process during the first 16 days. New CysRPs were identified for both organisms using public transcriptomic and genomic databases, while mRNA expression of CysRPs was analyzed by RT-qPCR. The results showed that N. parvum caused disease symptoms after 24 h that intensified over time. Through in silico analysis, 5 CysRPs were identified for each organism, revealing that all of the proteins are potentially secreted and novel, including two of N. parvum proteins containing the CFEM domain. Interestingly, the levels of the CysRPs mRNAs change during the interaction. This study reports N. parvum as a pathogen of L. styraciflua for the first time and highlights the potential involvement of CysRPs in both organisms during this interaction.

The nanoencapsulation of pesticides in biodegradable polymers confers several advantages to conventional agrochemicals, such as protection against losses due volatilization and degradation of the active ingredient, as well as the augment of water dispersion, allowing for their application on crops without requiring the use of organic solvents that could harm the user and the environment. This characteristics could enhance the productivity, reducing both costs and environmental pollution. In this work the propiconazole fungicide, forming part of a commercial formulation as well as in its pure state, was encapsulated using as carriers the biodegradable polymer poly lactic acid (PLA) and the biodegradable co-polymer poly (lactic-co-glicolic) acid, all with the aim of generate controlled fungicide release systems to augment the efficiency of the treatments of the Fusarium dieback disease. The most efficient system obtained presented nanospheres of 146.28 nm and an encapsulation efficiency over 42%. The antifungal activity tests showed that the use of this nanoencapsulated fungicide system enhances the growth inhibition percentage in 5%, obtaining a formulation that presents good dispersion in water without the need of organic emulsifier agents.

Background The Ambrosia Fusarium Clade phytopathogenic Fusarium fungi species have a symbiotic relationship with ambrosia beetles in the genus Euwallacea (Coleoptera: Curculionidae). Related beetle species referred to as Euwallacea sp. near fornicatus have been spread in California, USA and are recognized as the causal agents of Fusarium dieback, a disease that causes mortality of many plant species. Despite the importance of this fungi, no transcriptomic resources have been generated. The datasets described here represent the first ever transcripts available for these species. We focused our study on the isolated species of Fusarium that is associated with one of the cryptic species referred to as Kuroshio Shot Hole Borer (KSHB) Euwallacea sp. near fornicatus. Results Hydrogen concentration is a critical signal in fungi for growth and host colonization, the aim of this study was to evaluate the effect of different pH conditions on growth and gene expression of the fungus Fusarium sp. associated with KSHB. An RNA-seq approach was used to compare the gene expression of the fungus grown for 2 weeks in liquid medium at three different pH levels (5.0, 6.0, and 7.0). An unbuffered treatment was included to evaluate the capability of the fungus to change the pH of its environment and the impact in gene expression. The results showed that the fungus can grow and modulate its genetic expression at different pH conditions; however, growth was stunted in acidic pH in comparison with neutral pH. The results showed a differential expression pattern in each pH condition even when acidic conditions prevailed at the end of the experiment. After comparing transcriptomics data from the three treatments, we found a total of 4,943 unique transcripts that were differentially expressed. Conclusions We identified transcripts related to pH signaling such as the conserved PAL/RIM pathway, some transcripts related to secondary metabolism and other transcripts that were differentially expressed. Our analysis suggests possible mechanisms involved in pathogenicity in this novel Fusarium species. This is the first report that shows transcriptomic data of this pathogen as well as the first report of genes and proteins involved in their metabolism identifying potential virulence factors. Electronic supplementary material The online version of this article (10.1186/s12864-018-5083-1) contains supplementary material, which is available to authorized users.

Zinc is a micronutrient required for symbiotic nitrogen fixation. It has been proposed that in model legumeMedicago truncatula, zinc is delivered in a similar fashion as iron,i.e.by the root vasculature into the nodule and released in the infection/differentiation zone. There, zinc transporters must introduce this element into rhizobia-infected cells to metallate the apoproteins that use zinc as a cofactor.MtZIP6(Medtr4g083570) is aM. truncatulaZinc-Iron Permease (ZIP) that is expressed only in roots and nodules, with the highest expression levels in the infection/differentiation zone. Immunolocalization studies indicate that it is located in the plasma membrane of rhizobia-infected cells in the nodule. Down-regulatingMtZIP6expression levels with RNAi does not result in any strong phenotype when plants are being watered with mineral nitrogen. However, these silenced plants displayed severe growth defects when they depended on nitrogen fixed by their nodules, as a consequence of the loss of 80% of their nitrogenase activity. The reduction of this activity was not the result of iron not reaching the nodule, but an indirect effect of zinc being retained in the infection/differentiation zone and not reaching the cytosol of rhizobia-infected cells. These data are consistent with a model in which MtZIP6 would be responsible for zinc uptake by rhizobia-infected nodule cells in the infection/differentiation zone.

Here, we report the genome of Fusarium euwallaceae strain HFEW-16-IV-019, an isolate obtained from Kuroshio shot hole borer (a Euwallacea sp.). These beetles were collected in Tijuana, Mexico, from elm trees showing typical symptoms of Fusarium dieback. The final assembly consists of 287 scaffolds spanning 48,274,071 bp and 13,777 genes.

Paramount to symbiotic nitrogen fixation (SNF) is the synthesis of a number of metalloenzymes that use iron as a critical component of their catalytical core. Since this process is carried out by endosymbiotic rhizobia living in legume root nodules, the mechanisms involved in iron delivery to the rhizobia-containing cells are critical for SNF. In order to gain insight into iron transport to the nodule, we have used synchrotron-based X-ray fluorescence to determine the spatio-temporal distribution of this metal in nodules of the legume Medicago truncatula with hitherto unattained sensitivity and resolution. The data support a model in which iron is released from the vasculature into the apoplast of the infection/differentiation zone of the nodule (zone II). The infected cell subsequently takes up this apoplastic iron and delivers it to the symbiosome and the secretory system to synthesize ferroproteins. Upon senescence, iron is relocated to the vasculature to be reused by the shoot. These observations highlight the important role of yet to be discovered metal transporters in iron compartmentalization in the nodule and in the recovery of an essential and scarce nutrient for flowering and seed production.