Preparation of porous biochar from fusarium wilt-infected banana straw for remediation of cadmium pollution in water bodies.

The problem of cadmium pollution and its control is becoming increasingly severe issue in the world. Banana straw is an abundant bio raw material, but its burning or discarding in field not only causes pollution but also spreads fusarium wilt. The objective of this paper is to utilize biochar derived from the wilt-infected banana straw for remediation of Cd(II) pollution while to eliminate the pathogen. The activity of wilt pathogen in biochar was determined by PDA petri dish test. The Cd(II) adsorption of the biochar was determined by batch adsorption experiments. The effects of KOH concentration (0.25, 0.5 and 0.75 M) on the physicochemical characteristics of the biochar were also observed by BET, SEM, FTIR, XRD and XPS. Results showed that pristine banana straw biochar (PBBC) did not harbor any pathogen. The specific surface area (SSA) and Cd(II) adsorption capacity of 0.75 M KOH modified banana straw biochar (MBBC0.75M) were increased by 247.2% and 46.1% compared to that of PBBC, respectively. Cd(II) adsorption by MBBC0.75M was suitable to be described by the pseudo-second-order kinetic model and Freundlich isotherm. After Cd(II) adsorption, the CdCO3 were confirmed by XRD and observed through SEM. The weakness and shift of oxygen-containing functional groups in MBBC0.75M after Cd(II) adsorption implied that those groups were complexed with Cd(II). The results showed that pyrolysis could not only eliminate banana fusarium wilt, but also prepare porous biochar with the wilt-infected banana straw. The porous biochar possessed the potential to adsorb Cd(II) pollutants.

Genetic diversity of the banana Fusarium wilt pathogen in Cuba and across Latin America and the Caribbean.

Fusarium wilt of bananas (FWB) is a severe plant disease that leads to substantial losses in banana production worldwide. It remains a major concern for Cuban banana cultivation. The disease is caused by members of the soil-borne Fusarium oxysporum species complex. However, the genetic diversity among Fusarium species infecting bananas in Cuba has remained largely unexplored. In our comprehensive survey, we examined symptomatic banana plants across all production zones in the country, collecting 170 Fusarium isolates. Leveraging genotyping-by-sequencing and whole-genome comparisons, we investigated the genetic diversity within these isolates and compared it with a global Fusarium panel. Notably, typical FWB symptoms were observed in Bluggoe cooking bananas and Pisang Awak subgroups across 14 provinces. Our phylogenetic analysis revealed that F. purpurascens, F. phialophorum, and F. tardichlamydosporum are responsible for FWB in Cuba, with F. tardichlamydosporum dominating the population. Furthermore, we identified between five and seven distinct genetic clusters, with F. tardichlamydosporum isolates forming at least two subgroups. This finding underscores the high genetic diversity of Fusarium spp. contributing to FWB in the Americas. Our study sheds light on the population genetic structure and diversity of the FWB pathogen in Cuba and the broader Latin American and Caribbean regions.

Secreted in Xylem (SIX) genes in Fusarium oxysporum f.sp. cubense (Foc) unravels the potential biomarkers for early detection of Fusarium wilt disease.

Secreted in Xylem (SIX) are small effector proteins released by Fusarium oxysporum f.sp. cubense (Foc) into the plant's xylem sap disrupting the host's defence responses causing Fusarium wilt disease resulting in a significant decline in banana crop yields and economic losses. Notably, different races of Foc possess unique sets of SIX genes responsible for their virulence, however, these genes remain underutilized, despite their potential as biomarkers for early disease detection. Herein, we identified seven SIX genes i.e. SIX1, SIX2, SIX4, SIX6, SIX8a, SIX9a and SIX13 present in Foc Tropical Race 4 (FocTR4), while only SIX9b in Foc Race 1 (Foc1). Analysis of SIX gene expression in infected banana roots revealed differential patterns during infection providing valuable insights into host-pathogen interactions, virulence level, and early detection time points. Additionally, a comprehensive analysis of virulent Foc1_C2HIR and FocTR4_C1HIR isolates yielded informative genomic insights. Hence, these discoveries contribute to our comprehension of potential disease control targets in these plants, as well as enhancing plant diagnostics and breeding programs.

Pradimicin U, a promising antimicrobial agent isolated from a newly found Nonomuraea composti sp. nov.

Pradimicin U is a new dihydrobenzo[a]naphthacenequinone compound found to be active on a screen designed to investigate compounds with antimicrobial activity, produced by the actinomycete designated strain FMUSA5-5T. The strain was isolated from a bio-fertilizer of Musa spp. collected from Suphanburi province, Thailand. The chemotaxonomic characteristics and 16S rRNA gene analysis revealed that strain FMUSA5-5T is a member of the genus Nonomuraea. Low genome-based taxonomic criteria, average nucleotide identity (ANI) (82.8-88.3%), average amino-acid identity (AAI) (79.4-87.3%), and digital DNA-DNA hybridization (dDDH) (29.5-38.5%) values and several phenotypic differences between strain FMUSA5-5T and its closest type strains of the genus Nonomuraea indicated that strain FMUSA5-5T represents a novel species of the genus Nonomuraea and the name Nonomuraea composti sp. nov. is proposed for the strain. The crude extract from the culture broth of strain FMUSA5-5T displayed promising antimicrobial activity against several pathogens and led to the isolation of a novel secondary metabolite, pradimicin U. Interestingly, this compound displayed a broad spectrum of biological activities such as antimalarial activity against Plasmodium falciparum K1 (IC50 value = 3.65 µg/mL), anti-Mycobacterium tuberculosis H37Ra (MIC value = 25.0 µg/mL), anti-Alternaria brassicicola BCC 42724 (MIC value = 25.0 µg/mL), anti-Bacillus cereus ATCC 11778 and anti-Staphylococcus aureus ATCC 29213 (MIC values = 6.25 and 1.56 µg/mL, respectively). Moreover, the compound possessed strong anti-human small cell lung cancer (NCI-H187) activity with IC50 value of 5.69 µg/mL, while cytotoxicity against human breast cancer (MCF-7) and Vero cells was very weak (IC50 values of 52.49 and 21.84 µg/mL, respectively).

Molecular insights into the variability and pathogenicity of Fusarium odoratissimum, the causal agent of Panama wilt disease in banana.

Fusarium wilt or Panama disease of banana caused by the hemibiotroph fungus, Fusarium odoratissimum, also known as F. oxysporum f.sp. cubense Tropical Race 4 is a serious threat to banana production worldwide. Being the world's largest grower and the origins of bananas in its northeast region, India is particularly vulnerable to this deadly fungus. In the present study, a total of 163 Fusarium isolates from infected banana were characterized for their pathogenic traits. Considering the variability in the Fusarium, the contaminated banana plants were collected from five districts of Uttar Pradesh and Bihar, two major primary infection states of India. All the isolates were screened using universal and specific primers to identify the F. odoratissimum strains. The identified F. odoratissimum strains were subjected to in vivo pathogenicity assessment using the susceptible banana cultivar 'Grand Naine'. The identified six most virulent strains were further characterized for their pathogenicity via in vivo bipartite interaction in terms of biochemical assays. Assessment of in vivo pathogenicity through qRT-PCR for three pathogenesis responsive genes, Six 1a (Secreted in xylem), Snf (Sucrose non-fermenting) and ChsV (Chitinase V), ascertained that the identified F. odoratissimum strains exhibit both intra- and inter-specific variability. The variability of F. odoratissimum strains signifies its importance for the assessment of spread of infection at specific sites to enable efficient management strategy of Fusarium wilt in banana.

Codon usage bias of secretory protein in Fusarium oxysporum f. sp. cubense tropical race 4.

Banana Fusarium oxysporum f. sp. cubense tropical race 4 (Foc-TR4) is a highly destructive pathogen that infects nearly all major banana cultivars and has a tendency to spread further. Secreted proteins play a crucial role in the process of Fusarium wilt infection in bananas. In this study, we analyzed the codon usage bias (CUB) of the Foc-TR4 classical secretory protein genome for the first time and observed a strong bias toward codons ending with C. We found that 572 out of the 14,543 amino acid sequences in the Foc-TR4 genome exhibited characteristics of classical secretory proteins. The CUB was largely influenced by selection optimization pressure, as indicated by the ENC value and neutral plot analysis. Among the identified codons, such as UCC and CCC, 11 were found to be optimal for Foc-TR4 gene expression. Codons with higher GC content and a C base in the third position showed greater selectivity. The CUB in the secretory proteins encoded by Foc-TR4 provides insights into their evolutionary patterns, contributing to the development and screening of novel and effective antifungal drugs.

How do hedgerow characteristics alter the dispersal of Pseudocercospora fijiensis propagules?

BACKGROUND: Hedgerows represent an agroecological lever for pest management. To date, few studies have shown that they can be used as a lever for the control of aerial fungal diseases, especially as a barrier to dispersal. On banana production, the main disease is black leaf streak disease (BLSD), which is a fungal disease caused by Pseudocercospora fijiensis. This pathogen disperses through two types of spores: ascospore and conidia. The aim of this study was to observe and to quantify the effect of hedgerows on BLSD dispersal. Trap plants were placed at the same distance to an artificial source of inoculum with a hedgerow on one side. Lesions were counted to establish the daily lesion density of each trap plant. The combination of hedgerow characteristics such as height, width, and optical porosity were used to evaluate its potential capacity to intercept spores. RESULTS: When ascospores were used as a source of inoculum, the lesion density on traps plant decreased up to 50% between the hedgerow with the lowest interception capacities and the one with the highest interception capacities. For conidia, hedgerow height and side of the trap plants (with or without hedgerow between them and the source) were not significant, but low porosity of the hedgerow reduced the lesion density. On the contrary, for ascospore, the hedgerow effect was anisotropic; the trap plants on hedgerow side had less lesions. CONCLUSION: Our study is the first experimental proof of the effect of hedgerows on P. fijiensis dispersion, both on conidia and ascospore. We showed that hedgerow characteristics impact the capacity of interception of the hedgerow. © 2023 Society of Chemical Industry.

Chitosan from Marine Amphipods Inhibits the Wilt Banana Pathogen Fusarium oxysporum f. sp. Cubense Tropical Race 4.

In this work, we extracted chitosan from marine amphipods associated with aquaculture facilities and tested its use in crop protection. The obtained chitosan was 2.5 ± 0.3% of initial ground amphipod dry weight. The chemical nature of chitosan from amphipod extracts was confirmed via Raman scattering spectroscopy and Fourier transform infrared spectroscopy (FTIR). This chitosan showed an 85.7-84.3% deacetylation degree. Chitosan from biofouling amphipods at 1 mg·mL-1 virtually arrested conidia germination (ca. sixfold reduction from controls) of the banana wilt pathogenic fungus Fusarium oxysporum f. sp cubense Tropical Race 4 (FocTR4). This concentration reduced (ca. twofold) the conidia germination of the biocontrol fungus Pochonia chlamydosporia (Pc123). Chitosan from amphipods at low concentrations (0.01 mg·mL-1) still reduced FocTR4 germination but did not affect Pc123. This is the first time that chitosan is obtained from biofouling amphipods. This new chitosan valorizes aquaculture residues and has potential for biomanaging the diseases of food security crops such as bananas.

Molecular characterization of vermicompost-derived IAA-releasing bacterial isolates and assessment of their impact on the root improvement of banana during primary hardening.

The hardening step of micropropagation is crucial to make the in vitro raised plants mature and further enhancing their survivability in the external environment. Auxin regulates various root physiological parameters in plant systems. Therefore, the present study aimed to assess the impact of three vermicompost-derived IAA-releasing microbial strains, designated S1, S2, and S3, as biofertilizers on in vitro raised banana plantlets during primary hardening. The High-Performance Thin-Layer Chromatography (HPTLC) analysis of these strains revealed a higher IAA content for S1 and S2 than that of S3 after 144 h of incubation. In total, seven different treatments were applied to banana plantlets, and significant variations were observed in all plant growth parameters for all treatments except autoclaved cocopeat (100%) mixed with autoclaved vermicompost (100%) at a 1:1 ratio. Among these treatments, the application of S3 biofertilizer: autoclaved cocopeat (1:1), followed by S2 biofertlizer: autoclaved cocopeat (1:1), was found to be better than other treatments for root numbers per plant, root length per plant, root volume, and chlorophyll content. These findings have confirmed the beneficial effects of microbial strains on plant systems and propose a link between root improvement and bacterial auxin. Further, these strains were identified at the molecular level as Bacillus sp. As per our knowledge, this is the first report of Bacillus strains isolated from vermicompost and applied as biofertilizer along with cocopeat for the primary hardening of banana. This unique approach may be adopted to improve the quality of plants during hardening, which increases their survival under abiotic stresses.

Antifungal Potential of Melaleuca alternifolia against Fungal Pathogen Fusarium oxysporum f. sp. cubense Tropical Race 4.

Fusarium wilt of bananas caused by Fusarium oxysporum f. sp. cubense Tropical Race 4 (Foc TR4) poses the most serious threat to banana production globally. The disease has been managed using chemical fungicides, yet the control levels are still unsatisfactory. This study investigated the antifungal activities of tea tree (Melaleuca alternifolia) essential oil (TTO) and hydrosol (TTH) against Foc TR4 and their bioactive components. The potential of TTO and TTH in inhibiting the growth of Foc TR4 was evaluated in vitro using agar well diffusion and spore germination assays. Compared to the chemical fungicide, TTO effectively suppressed the mycelial growth of Foc TR4 at 69%. Both the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of TTO and TTH were established at 0.2 µg/µL and 50% v/v, respectively, suggesting the fungicidal nature of the plant extracts. The disease control efficacies were also demonstrated by a (p ≤ 0.05) delayed Fusarium wilt symptom development in the susceptible banana plants with reduced LSI dan RDI scores from 70% to around 20-30%. A GC/MS analysis of TTO identified terpinen-4-ol, eucalyptol, and α-terpineol as the major components. In contrast, an LC/MS analysis of TTH identified different compounds, including dihydro-jasmonic acid and methyl ester. Our findings indicate the potential of tea tree extracts as natural alternatives to chemical fungicides to control Foc TR4.

Moonlight-like proteins are actually cell wall components in Pseudocercospora fijiensis.

The fungal cell wall protects fungi against threats, both biotic and abiotic, and plays a role in pathogenicity by facilitating host adhesion, among other functions. Although carbohydrates (e.g. glucans, chitin) are the most abundant components, the fungal cell wall also harbors ionic proteins, proteins bound by disulfide bridges, alkali-extractable, SDS-extractable, and GPI-anchored proteins, among others; the latter consisting of suitable targets which can be used for fungal pathogen control. Pseudocercospora fijiensis is the causal agent of black Sigatoka disease, the principal threat to banana and plantain worldwide. Here, we report the isolation of the cell wall of this pathogen, followed by extensive washing to eliminate all loosely associated proteins and conserve those integrated to its cell wall. In the HF-pyridine protein fraction, one of the most abundant protein bands was recovered from SDS-PAGE gels, electro-eluted and sequenced. Seven proteins were identified from this band, none of which were GPI-anchored proteins. Instead, atypical (moonlight-like) cell wall proteins were identified, suggesting a new class of atypical proteins, bound to the cell wall by unknown linkages. Western blot and histological analyses of the cell wall fractions support that these proteins are true cell wall proteins, most likely involved in fungal pathogenesis/virulence, since they were found conserved in many fungal pathogens.

Revealing the different resistance mechanisms of banana 'Guijiao 9' to Fusarium oxysporum f. sp. cubense tropical race 4 using comparative proteomic analysis.

Fusarium wilt of banana caused by Fusarium oxysporum f. sp. cubense is a worldwide devastating fungal disease in the banana industry. The disease caused by Fusarium oxysporum f. sp. cubense is becoming more and more serious. The pathogen of Fusarium oxysporum f. sp. cubense tropical race 4 (Foc4) is the most harmful one. 'Guijiao 9' is a banana cultivar with good resistance to Foc4, which is identified by resistance screening of natural variant lines. It is of great significance to explore the resistance genes and key proteins of 'Guijiao 9' for banana cultivar improvement and disease resistance breeding. In this study, iTRAQ (isobaric Tags for Relative and Absolute quantitation) was used to analyze the xylem proteomic data of banana roots from the resistant variety 'Guijiao 9' and susceptible variety 'Williams', and the differences in protein accumulation profiles between these two varieties at 24, 48, and 72 h after infection with Foc4 were compared. The identified proteins were analyzed by the protein WGCNA (Weighted Gene Correlation Network Analysis), and the differentially expressed proteins (DEPs) were verified by qRT-PCR experiments. Proteomic analysis showed that there were differences in the protein accumulation profiles of the resistant cultivar 'Guijiao 9' and the susceptible cultivar 'Williams' after infection with Foc4, and there were differences in resistance-related proteins, biosynthesis of secondary metabolites, peroxidase, and pathogenesis-related proteins. The stress response of bananas to pathogens was affected by multiple factors. Protein co-expression analysis showed that there was a high correlation between the MEcyan module and resistance, and 'Guijiao 9' had a different resistance mechanism compared with 'Williams'. SIGNIFICANCE: 'Guijiao 9' is a banana variety with good resistance to Foc4, which is identified by screening the resistance of natural variant lines in the farmland where banana plants are seriously infected by Foc4. It is of great significance to excavate the resistance genes and key proteins of 'Guijiao 9' for banana variety improvement and disease resistance breeding. The aim of this paper is to identify the proteins and related functional modules controlling the pathogenicity differences of Foc4 by comparative proteomic analysis of 'Guijiao 9', so as to understand the resistance mechanism of banana to Fusarium wilt, and offer basis for the final identification, isolation and utilization of Foc4 resistance-related genes in banana variety improvement. The research results will also provide a basis for further understanding the host-pathogen interaction and revealing the resistance mechanism of bananas.

Association of soil fungal community composition with incidence of Fusarium wilt of banana in Malaysia.

Banana (Musa spp.), an important food crop in many parts of the world, is threatened by a deadly wilt disease caused by Fusarium oxysporum f. sp. cubense Tropical Race 4 (TR4). Increasing evidence indicates that plant actively recruits beneficial microbes in the rhizosphere to suppress soil-borne pathogens. Hence, studies on the composition and diversity of the root-associated microbial communities are important for banana health. Research on beneficial microbial communities has focused on bacteria, although fungi can also influence soil-borne disease. Here, high-throughput sequencing targeting the fungal internal transcribed spacer (ITS) was employed to systematically characterize the difference in the soil fungal community associated with Fusarium wilt (FW) of banana. The community structure of fungi in the healthy and TR4-infected rhizospheres was significantly different compared with that of bulk soil within the same farm. The rhizosphere soils of infected plants exhibited higher richness and diversity compared with healthy plants, with significant abundance of Fusarium genus at 14%. In the healthy rhizosphere soil, Penicillium spp. were more abundant at 7% and positively correlated with magnesium. This study produced a detailed description of fungal community structure in healthy and TR4-infected banana soils in Malaysia and identified candidate biomarker taxa that may be associated with FW disease promotion and suppression. The findings also expand the global inventory of fungal communities associated with the components of asymptomatic and symptomatic banana plants infected by TR4.

Additive fungal interactions drive biocontrol of Fusarium wilt disease.

Host-associated fungi can help protect plants from pathogens, and empirical evidence suggests that such microorganisms can be manipulated by introducing probiotic to increase disease suppression. However, we still generally lack the mechanistic knowledge of what determines the success of probiotic application, hampering the development of reliable disease suppression strategies. We conducted a three-season consecutive microcosm experiment in which we amended banana Fusarium wilt disease-conducive soil with Trichoderma-amended biofertilizer or lacking this inoculum. High-throughput sequencing was complemented with cultivation-based methods to follow changes in fungal microbiome and explore potential links with plant health. Trichoderma application increased banana biomass by decreasing disease incidence by up to 72%, and this effect was attributed to changes in fungal microbiome, including the reduction in Fusarium oxysporum density and enrichment of pathogen-suppressing fungi (Humicola). These changes were accompanied by an expansion in microbial carbon resource utilization potential, features that contribute to disease suppression. We further demonstrated the disease suppression actions of Trichoderma-Humicola consortia, and results suggest niche overlap with pathogen and induction of plant systemic resistance may be mechanisms driving the observed biocontrol effects. Together, we demonstrate that fungal inoculants can modify the composition and functioning of the resident soil fungal microbiome to suppress soilborne disease.

Dissemination of Fusarium Wilt of Banana in Mozambique Caused by Fusarium odoratissimum Tropical Race 4.

Fusarium wilt of banana (FWB) is a serious soil-borne fungal disease. In the previous century, FWB already destroyed Gros Michel-based banana cultures in Central America, and currently, the disease threatens all major banana-producing regions of the world. The causal agents of these epidemics, however, are diverse. Gros Michel was infected by a wide range of Fusarium species, the so-called Race 1 strains, whereas the contemporary Cavendish-based cultures are affected by Fusarium odoratissimum, colloquially called Tropical Race 4 (TR4). TR4 was reported in Mozambique on two commercial banana farms in 2013, but no incursions were found outside the farm boundaries in 2015, suggesting that the disease was under control. Here we report the presence of TR4 outside of these farm boundaries. We obtained fungal samples from 13 banana plants in smallholder and roadside plantings at various locations throughout northern Mozambique. These samples tested positive for TR4 by molecular diagnostics and in greenhouse pathogenicity assays. The results were confirmed with reisolations, thereby completing Koch's postulates. To study the diversity of TR4 isolates in Mozambique, we selected five samples for whole-genome sequencing. Comparison with a global collection of TR4 samples revealed very little genetic variation, indicating that the fungus is clonally spreading in Mozambique. Furthermore, isolates from Mozambique are clearly genetically separated from other geographic incursions, and thus we cannot trace the origin of TR4 in Mozambique. Nevertheless, our data demonstrates the dissemination of TR4 in Mozambique, underscoring the failure of disease management strategies. This threatens African banana production.

Genome Sequence Data Reveal at Least Two Distinct Incursions of the Tropical Race 4 Variant of Fusarium Wilt into South America.

The global banana industry is threatened by one of the most devastating diseases: Fusarium wilt of banana. Fusarium wilt of banana is caused by the soilborne fungus Fusarium oxysporum f. sp. cubense (Foc), which almost annihilated the banana production in the late 1950s. A new strain of Foc, known as tropical race 4 (TR4), attacks a wide range of banana varieties, including Cavendish clones, which are the source of 99% of banana exports. In 2019, Foc TR4 was reported in Colombia, and more recently (2021) in Peru. In this study, we sequenced three fungal isolates identified as Foc TR4 from La Guajira (Colombia) and compared them against 19 whole-genome sequences of Foc TR4 publicly available, including four genome sequences recently released from Peru. To understand the genetic relatedness of the Colombian Foc TR4 isolates and those from Peru, we conducted a phylogenetic analysis based on a genome-wide set of single nucleotide polymorphisms (SNPs). Additionally, we compared the genomes of the 22 available Foc TR4 isolates, looking for the presence-absence of gene polymorphisms and genomic regions. Our results reveal that (i) the Colombian and Peruvian isolates are genetically distant, which could be better explained by independent incursions of the pathogen to the continent, and (ii) there is a high correspondence between the genetic relatedness and geographic origin of Foc TR4. The profile of present/absent genes and the distribution of missing genomic regions showed a high correspondence to the clades recovered in the phylogenetic analysis, supporting the results obtained by SNP-based phylogeny.

Antagonism of volatile organic compounds of the Bacillus sp. against Fusarium kalimantanense.

Fusarium kalimantanense is a genetic lineage of Fusarium oxysporum f. sp. cubense (Foc) and belongs to the Fusarium oxysporum species complex (FOSC). This pathogen is a causative agent of Panama disease, an infection that has caused damage to the banana crop worldwide. Bacillus sp. (LPPC170) showed preliminary antagonist activity against F. kalimantanense (LPPC130) in vitro tests from the cultivation of axenic culture and co-culture with inhibition of mycelial growth of phytopathogen of 41.23%. According to these findings, volatile organic compounds (VOCs) emitted from Bacillus sp. were obtained by solid-phase microextraction and identified by gas chromatography coupled with a mass spectrometer (GC-MS). The multivariate data analysis tool (PLS-DA and Heatmap) identified short-chain organic acids as the main antagonistic VOCs responsible for inhibiting the mycelial growth of LPPC130. Acetic acid, propanoic acid, butanoic acid, valeric acid, and isovaleric acid exhibited a strong inhibitory effect on the mycelial growth of LPPC130, with inhibition of 20.68%, 33.30%, 26.87%, 43.71%, and 53.10%, respectively. Scanning electron microscopy revealed that VOCs caused damage to the vegetative and reproductive structures of the fungus. These results suggest Bacillus LPPC170 as an excellent biocontrol tool against the phytopathogen causative agents of Panama disease.

Autochthonous endophytic bacteria from Musa sp. controls Fusarium oxysporum f. sp. cubense under in vitro conditions.

Fusarium wilt caused by Fusarium oxysporum f. sp. cubense (foc) is one of the main diseases affecting banana crops. Biological control emerges as an alternative technology to prevent the spread of the disease. The objective of this work was to evaluate the effects of endophytic bacteria isolated from banana Prata Anã challenged with the foc in pairing and volatile tests under in vitro conditions. Forty endophytic isolates of the genera Bacillus, Klebsiella, Paenibacillus, Stenotrophomonas, Lysinibacillus and Sporolactobacillus isolated from banana roots were challenged with foc. The principal component analysis showed that the spore germination variable in the presence of bacterial cells explained better the variance (29.88%). Spore germination in the presence of bacterial cells, number of spores/cm2 in paired and volatile tests, and colony area in volatile tests explained about 86.10% of the total variance observed. The isolate EB37 (Bacillus sp., JN215502.1) reduced 96% of the germination of Fusarium oxysporum f. sp. cubense spores. The UPMGA clustering method based on Euclidean distance divides the 40 endophytic bacteria isolates into eight groups. The autochthonous bacteria isolated from Musa sp. of the genera Bacillus, Lysinibacillus, Stenotrophomonas, Sporolactobacillus and Paenibacillus showed promising results in foc control under in vitro conditions.

Transcriptome Profiling of the Resistance Response of Musa acuminata subsp. burmannicoides, var. Calcutta 4 to Pseudocercospora musae.

Banana (Musa spp.), which is one of the world's most popular and most traded fruits, is highly susceptible to pests and diseases. Pseudocercospora musae, responsible for Sigatoka leaf spot disease, is a principal fungal pathogen of Musa spp., resulting in serious economic damage to cultivars in the Cavendish subgroup. The aim of this study was to characterize genetic components of the early immune response to P. musae in Musa acuminata subsp. burmannicoides, var. Calcutta 4, a resistant wild diploid. Leaf RNA samples were extracted from Calcutta 4 three days after inoculation with fungal conidiospores, with paired-end sequencing conducted in inoculated and non-inoculated controls using lllumina HiSeq 4000 technology. Following mapping to the reference M. acuminata ssp. malaccensis var. Pahang genome, differentially expressed genes (DEGs) were identified and expression representation analyzed on the basis of gene ontology enrichment, Kyoto Encyclopedia of Genes and Genomes orthology and MapMan pathway analysis. Sequence data mapped to 29,757 gene transcript models in the reference Musa genome. A total of 1073 DEGs were identified in pathogen-inoculated cDNA libraries, in comparison to non-inoculated controls, with 32% overexpressed. GO enrichment analysis revealed common assignment to terms that included chitin binding, chitinase activity, pattern binding, oxidoreductase activity and transcription factor (TF) activity. Allocation to KEGG pathways revealed DEGs associated with environmental information processing, signaling, biosynthesis of secondary metabolites, and metabolism of terpenoids and polyketides. With 144 up-regulated DEGs potentially involved in biotic stress response pathways, including genes involved in cell wall reinforcement, PTI responses, TF regulation, phytohormone signaling and secondary metabolism, data demonstrated diverse early-stage defense responses to P. musae. With increased understanding of the defense responses occurring during the incompatible interaction in resistant Calcutta 4, these data are appropriate for the development of effective disease management approaches based on genetic improvement through introgression of candidate genes in superior cultivars.

Dynamic analysis of the microbial communities and metabolome of healthy banana rhizosphere soil during one growth cycle.

Background: The banana-growing rhizosphere soil ecosystem is very complex and consists of an entangled network of interactions between banana plants, microbes and soil, so identifying key components in banana production is difficult. Most of the previous studies on these interactions ignore the role of the banana plant. At present, there is no research on the the micro-ecological environment of the banana planting growth cycle. Methods: Based on high-throughput sequencing technology and metabolomics technology, this study analyzed the rhizosphere soil microbial community and metabolic dynamics of healthy banana plants during one growth cycle. Results: Assessing the microbial community composition of healthy banana rhizosphere soil, we found that the bacteria with the highest levels were Proteobacteria, Chloroflexi, and Acidobacteria, and the dominant fungi were Ascomycota, Basidiomycota, and Mortierellomycota. The metabolite profile of healthy banana rhizosphere soil showed that sugars, lipids and organic acids were the most abundant, accounting for about 50% of the total metabolites. The correlation network between fungi and metabolites was more complex than that of bacteria and metabolites. In a soil environment with acidic pH, bacterial genera showed a significant negative correlation with pH value, while fungal genera showed no significant negative correlation with pH value. The network interactions between bacteria, between fungi, and between bacteria and fungi were all positively correlated. Conclusions: Healthy banana rhizosphere soil not only has a stable micro-ecology, but also has stable metabolic characteristics. The microorganisms in healthy banana rhizosphere soil have mutually beneficial rather than competitive relationships.