Severe Fungal Diseases Research Articles

Assessment of inhibitory potentiality of natural compounds against worrisome rice blast fungus

Rice blast, a severe fungal disease, is a substantial threat to global food security, particularly in rice-oriented areas. The Magnaporthe oryzae fungus is increasingly resistant and fast developing in nature. However, chemical fungicides are not only detrimental to the environment but eventually also lose their efficiency. To Tackle this issue, we used an in silico based strategy to identify plant metabolites as bio-fungicides to combat rice blast. Therefore, we screened a total of 56 antifungal natural compounds for the ability to inhibit fungal development through the targeted inhibition of essential proteins in the rice blast pathogen. Molecular docking analysis identified curcumin, myricetin, sterigmatocystin, and versicolorin B as promising candidates with superior binding affinities compared to conventional fungicides like strobilurin, azoxystrobin, and tricyclazole. Notably, myricetin showed the docking score for the SD protein of −233.20, whereas versicolorin B demonstrated the highest binding affinity for the SD protein of −234.23. Among the control fungicides, azoxystrobin displayed the lowest docking score of −177.53. The docked complexes were found to be stable based on molecular dynamics simulations results; the binding free energies of SD-Versicolorin B (−156.018 ± 24.881 kJ/mol) and SD-Myricetin (−137.526 ± 19.977 kJ/mol) complexes were also found to be favorable. Taking everything considered, these naturally occurring substances showed strong fungicidal effects against rice blast causative agent while remaining non-toxic, providing encouraging substitutes for traditional fungicides. In conclusion, these non-toxic natural compounds exhibited strong fungicidal action against rice blast, suggesting promising alternatives to conventional fungicides.

Impact of Fab1/Vac14 inhibition on β-1,3-glucanase localization at the tip in Saccharomyces cerevisiae

Deep mycosis is a severe fungal disease that could result in fatal outcomes. However, there is still a demand for highly effective and safe antifungal drugs, given the side effects of the existing treatments and the increase in the resistance to them. In this study, we evaluated the involvement of the lipid kinase Fab1 and its activator Vac14 (Fab1/Vac14) in tip growth in Saccharomyces cerevisiae INVSc1, along with their impact on cell proliferation, using a genetic approach to inhibit them. The results revealed that Fab1/Vac14 inhibition suppressed growth and caused an increase in the rate of β-1,3-glucanase (BGL2) fused with emerald green fluorescent protein (EmGFP) (BGL2-EmGFP) localization at the tip. The inhibition of the endocytic pathway using a lysosome inhibitor also resulted in an increased localization of BGL2-EmGFP at the tip. The overexpression of wild-type BGL2-EmGFP, but not that of the inactive mutant BGL2, led to a complete loss of the cell proliferation ability. These findings suggested that the Fab1/Vac14 complex could be a novel target for the development of antifungal drugs based on tip growth regulation, possibly via excessive cell wall degradation.

Occurrence of Botrytis cinerea Causing Gray Mold on Pecan in China

Pecan (Carya illinoinensis), a globally economically significant dried fruit and woody oil tree, faces significant challenges in production and nut quality due to the rampant outbreak of severe fungal diseases. From 2020 to 2021, an extensive occurrence of a disease resembling gray mold was observed on the leaves and fruits of pecan trees in Jiangsu Province, China. Upon isolation from symptomatic samples, Botrytis cinerea was identified through morphological analysis and phylogenetic studies of the G3PDH, HSP60, and RPB2 gene sequences. Furthermore, pathogenicity tests conclusively attributed the gray mold disease observed on pecan leaves and fruits to B. cinerea. To the best of our knowledge, this is the first time that B. cinerea has been reported on pecans. These findings thus provide a basis for further research on the management of pecan gray mold.

DESEMPENHO DA PRODUTIVIDADE DE MILHO A PARTIR DE APLICAÇÃO DE FUNGICIDA EM DIFERENTES ESTÁGIOS FENOLÓGICOS

Corn (Zea mays L.) is a crucial crop in terms of global production and economic value, but it is susceptible to fungal diseases such as common rust (Puccinia sorghi) and cercosporiosis (Cercospora zeae-maydis), which can reduce grain production and quality. Effective control of these diseases is vital for food security and agricultural economy. Proper management of corn fungal diseases depends on the plant's phenological stages, from planting to grain maturity. The application of fungicides at strategic moments during the plant's life cycle is essential to prevent infections and reduce disease impact. A study conducted in Patos de Minas, Minas Gerais, during 2023, evaluated the effect of fungicide application at different phenological stages of corn on final productivity. The results showed that fungicide application at multiple phenological stages (V4, V8, and VT) resulted in greater above-ground height, lower severity of fungal diseases, higher productivity, and uniform stalk diameter compared to the control treatment. This integrated disease management method proved effective in protecting plants against fungal diseases, promoting healthier and more vigorous growth, and increasing final corn productivity. These findings highlight the importance of fungicide application at strategic moments in the corn development cycle to maximize productivity and promote more efficient and sustainable agriculture.

Methyl jasmonate mitigates Fusarium graminearum infection in wheat by inhibiting deoxynivalenol synthesis.

Methyl jasmonate (MeJA), a plant growth regulator, coordinates a diverse array of physiological responses, including the inhibition of seed germination, modulation of secondary metabolite biosynthesis, and activation of defence responses. The external application of MeJA has been demonstrated to effectively diminish the severity of fungal diseases. Here, we unveil a novel mechanism through which exogenous MeJA alleviates Fusarium head blight (FHB) by inhibiting the synthesis of deoxynivalenol (DON) in Fusarium graminearum, rather than by enhancing the wheat resistance response. MeJA treatment reduced the infection by wild-type F. graminearum in wheat coleoptiles, but exhibited no significant influence on that of the DON-deficient mutant strain (∆Tri5). The production of DON in F. graminearum was significantly inhibited both in vitro and in planta. MeJA affected the expression of genes related to DON biosynthesis, without influencing the formation of toxisomes as observed under microscopic analysis. Exogenous MeJA demonstrated a limited impact on the early genes of plant jasmonic acid signalling pathway, in contrast to the wild-type pathogen strain, which induced the upregulation of these genes. The expression levels of defence marker genes induced by MeJA were notably lower compared to those induced by the pathogen. This study elucidates the molecular mechanisms of MeJA in modulating the wheat-F. graminearum interaction, providing new insights into the development of environmentally friendly strategies against fungi.

Exploring the molecular mechanisms of rice blast resistance and advances in breeding for disease tolerance.

Rice blast, caused by the fungus Magnaporthe oryzae (syn. Pyricularia oryzae), is a major problem in rice cultivation and ranks among the most severe fungal diseases. Cloning and identifying resistance genes in rice, coupled with a comprehensive examination of the interaction between M. oryzae and rice, may provide insights into the mechanisms of rice disease resistance and facilitate the creation of new rice varieties with improved germplasm. These efforts are essential for protecting food security. This review examines the discovery of genes that confer resistance or susceptiblity to M. oryzae in rice over the last decade. It also discusses how knowledge of molecular mechanisms has been used in rice breeding and outlines key strategies for creating rice varieties resistant to this disease. The strategies discussed include gene pyramiding, molecular design breeding, editing susceptibility genes, and increasing expression of resistance genes through pathogen challenge. We address the prospects and challenges in breeding for rice blast resistance, emphasizing the need to fully exploit germplasm resources, employ cutting-edge methods to identify new resistance genes, and develop innovative breeding cultivars. Additionally, we underscore the importance of understanding the molecular basis of rice blast resistance and developing novel cultivars with broad-spectrum disease resistance.

An asymptomatic geminivirus activates autophagy and enhances plant defenses against diverse pathogens

Plant viral diseases cause great losses in agricultural production. Virus cross-protection is a strategy in which a mild virus is employed to shield plants against subsequent infections by severe viral strains. However, this approach is restricted to protection against the same viruses. In this study, we observed that pre-inoculation with apple geminivirus (AGV) reduced the accumulation of secondarily infected heterologous viruses, such as cucumber mosaic virus, potato virus X, and tobacco mosaic virus in Nicotiana benthamiana, tomato, and pepper plants. Transcriptional expression analysis showed that autophagy-related genes were transcriptionally up-regulated upon AGV inoculation at an early stage of infection. Accordingly, autophagic activity was observed to be elevated following AGV infection. Interestingly, AGV accumulation was reduced in autophagy-deficient plants, suggesting that autophagy activation promotes AGV infection in the plant. Moreover, pre-inoculation with AGV provided cross-protection against infection with a phytopathogenic bacterium (Pseudomonas syringae) and fungus (Botrytis cinerea) in Nicotiana species. In summary, our study showed that AGV, an asymptomatic virus, could protect plants against severe viral, fungal, and bacterial diseases to some extent through the activation of autophagy pathways, highlighting its potential as a biocontrol agent for managing a wide range of plant crop diseases in the field.

La enfermedad fúngica: el acoso y derribo del más débil

Fungal diseases encompass a wide range of conditions, from superficial skin infections to potentially life-threatening systemic diseases. The burden of severe fungal diseases is considerable, with millions of cases annually and high mortality rates. However, accurate epidemiological information is lacking due to limited surveillance. Their diagnosis and treatment present significant challenges, especially in resource-limited settings. Globally, there is a notable shortage of specialists experienced in fungal diseases. This scarcity contributes to delays in diagnosis and empirical treatment, with the consequences that this entails for the patient. The integration of artificial intelligence into medical practice promises to improve the diagnosis and management of fungal diseases. However, careful validation and training of algorithms are essential to ensure their effectiveness and equity. In conclusion, we call on relevant institutions to recognize the need for public funding for a project whose sole aim is to ensure that fungal diseases are incorporated into the realm of equal opportunities and rights, rather than remaining hidden and relegated to elitist institutions where professionals have the knowledge and tools to diagnose and treat them.

A MYB family transcription factor TdRCA1 from wild emmer wheat regulates anthocyanin biosynthesis in coleoptile.

As important secondary metabolites in plants, anthocyanins not only contribute to colored plants organs, but also provide protections against various biotic and abiotic stresses. In this study, a MYB transcription factor gene TdRCA1 from wild emmer wheat regulating anthocyanin biosynthesis in wheat coleoptile was identified on the short arm of chromosome 7A in common wheat genetic background. The TdRCA1 overexpression lines showed colored callus, coleoptile, auricle and stem nodes, as well as up regulation of six anthocyanin-related structural genes. The expression of TdRCA1 was activated by light in a temporal manner. While coleoptile color of 48 and 60h dark-grown seedlings changed from green to red after 24h light treatment, those grown in dark for 72 and 96h failed to develop red coleoptiles after light restoration. Interestingly, the over expression of TdRCA1 resulted in increased resistance to Fusarium crown rot, a chronic and severe fungal disease in many cereal growing regions in the world. Our results offer a better understanding of the molecular basis of coleoptile color in bread wheat.

First report of Colletotrichum scovillei causing anthracnose fruit rot of pepper in Ohio.

In August 2019, the Ohio State University Vegetable Pathology laboratory received multiple bell and banana pepper fruits (Capsicum annuum, cvs. unknown) from Columbiana County, Ohio. The grower reported a disease incidence of 100% and severity of 70% in fruits across their pepper fields. Fruit lesions were brown, sunken, and covered with orange-colored sporulation. On banana peppers, the lesions mainly affected the blossom end of the fruits, while the lesions were distributed randomly on bell pepper fruits. Pieces of diseased tissue were cut from the fruit and surface sterilized in 0.5-0.6 % sodium hypochlorite, rinsed in sterile water, blotted dry, and placed on potato dextrose agar. All of the fungal cultures recovered were cottony, pale gray-green with shades of orange on the underside of the mycelial mat. Two representative isolates, SM209-19 (bell pepper) and SM210-19 (banana pepper), were grown on oatmeal agar to induce sporulation. Pink-orange concentric rings containing acervuli and conidia were present on the oatmeal agar plates after one week of growth at 22◦C (12-h dark/light). Conidia (n=29) were hyaline, aseptate, cylindrical in shape, and had an average length of 10.5 µm (std. dev. = 1.3 µm) and width of 4.1 µm (std. dev. = 0.6 µm) (Fig.1). DNA was extracted from both isolates using a DNeasy Plant Kit (Qiagen Inc, Germantown, MD), and partial sequences of the internal transcribed spacer (ITS) region, -tubulin 2 gene (TUB2), and glyceraldehyde-3-phosphate dehydrogenase gene (GDPH) were amplified by PCR with the following primers: ITS4/ITS5 (White et al. 1990), Bt1a/Bt1b (Glass et al. 1995), and GDF1/GDR1 (Guerber et al. 2003), and squenced. The ITS region of both isolates SM209-19 and SM210-19 (PP280815 and PP280816, respectively) showed 100% identity with C. scovillei (Cs) isolate LJTJ35 (KP748226). The partial sequences of GDPH, (PP320348, PP320349, respectively) showed 99% sequence identity with the Cs CBS 126528 (JQ948597) and 100% identity with Cs HP1 (MT826948) The partial sequences of TUB2 (PP472464 and PP472465, respectively) had 100% sequence similarity with the Cs HP1 and Cs CBS 126528 (MT826951, JQ949918 respectively). Pathogenicity was tested in a greenhouse experiment on blossoming bell pepper plants (cv. Carmen) by spraying 10 ml of 1 X 105 conidia/ml suspension onto flower blooms (nine plants per isolate). Control pepper plants were mock inoculated by spraying 10 mL of sterile deionized water. The plants were re-inoculated one week later. Brown, sunken lesions with orange sporulation developed on the fruits of inoculated plants 21 days after the initial inoculation (Fig. 2), while the mock-inoculated plants did not produce any symptoms. Culturing from symptomatic fruits on PDA, following the same method described above, produced fungal colonies with the same morphological traits previously described. C. scovillei causing anthracnose on pepper has been described in the US (Toporek et al. 2021), Brazil (Caires et al. 2014), China (Zhao et al. 2016), and different South Asia Countries (Khalimi et al. 2019). Open-field peppers are produced in Ohio on more than 5,400 acres, with a value of more than $53 million, with anthracnose being one of the most severe fungal diseases reducing yield. This newly reported Colletotichum species could represent a further threat for this crop. Further studies evaluating fungicide sensitivity and efficacy against this pathogen will be of crucial importance for disease management.

A novel hypovirulence-associated Hadaka virus 1 (HadV1-LA6) in Fusarium oxysporum f. sp. cubense.

Fusarium oxysporum f. sp. cubense (Foc) poses a significant threat to banana crops as a lethal fungal pathogen. The global spread of Foc underscores the formidable challenges associated with traditional management methods in combating this pathogen. This study delves into the hypovirulence-associated mycovirus in Foc. From Foc strain LA6, we isolated and characterized a novel member of the Hadakaviridae family, named Hadaka virus 1 strain LA6 (HadV1-LA6). HadV1-LA6 comprises 10 genomic RNA segments, with RNA1 to RNA7 sharing 80.9%-95.0% amino acid sequence identity with known HadV1-7n, while RNA8 to RNA10 display significantly lower identity. HadV1-LA6 demonstrates horizontal transmission capabilities in an all-or-none fashion between different Foc strains via coculturing. Phenotypic comparisons highlight that HadV1-LA6 significantly reduces the growth rates of its host fungus under cell wall stress and oxidative stress conditions. Importantly, HadV1-LA6 attenuates Foc's virulence in detached leaves and banana plants. This study represents the first introduction of a novel hypovirulence-associated Hadaka virus 1 in Foc.IMPORTANCEFusarium wilt of banana (FWB) is a severe fungal disease caused by soil-borne Fusarium oxysporum f. sp. cubense (Foc). Among various strategies, biocontrol emerges as a safe, ecologically friendly, and cost-effective approach to managing FWB. In this study, we focus on exploring the potential of a novel hypovirulent member of hadakavirid, HadV1-LA6. Previous reports suggest that HadV1 shows no apparent effect on the host. However, through phenotypic assessments, we demonstrate that HadV1-LA6 significantly impedes the growth rates of its host fungus under stress conditions. More importantly, HadV1-LA6 exhibits a remarkable capacity to attenuate Foc's virulence in detached leaves and banana plants. Furthermore, HadV1-LA6 could be horizontally transmitted between different Foc strains, presenting a promising resource for revealing the molecular mechanism of the interaction between Hadaka virus 1 and its host.

Severe CSF immune cell alterations in cryptococcal meningitis gradually resolve during antifungal therapy

Cryptococcal meningitis (CM) is a severe fungal disease in immunocompromised patients affecting the central nervous system (CNS). Host response and immunological alterations in the cerebrospinal fluid (CSF) after invasion of Cryptococcus neoformans to the central nervous system have been investigated before but rigorous and comprehensive studies examining cellular changes in the CSF of patients with cryptococccal meningitis are still rare. We retrospectively collected CSF analysis and flow cytometry data of CSF and blood in patients with CM (n = 7) and compared them to HIV positive patients without meningitis (n = 13) and HIV negative healthy controls (n = 7). Within the group of patients with CM we compared those with HIV infection (n = 3) or other immunocompromised conditions (n = 4). Flow cytometry analysis revealed an elevation of natural killer cells and natural killer T cells in the CSF and blood of HIV negative patients with CM, pointing to innate immune activation in early stages after fungal invasion. HIV positive patients with CM exhibited stronger blood-CSF-barrier disruption. Follow-up CSF analysis over up to 150 days showed heterogeneous cellular courses in CM patients with slow normalization of CSF after induction of antifungal therapy.

The miR7125-MdARF1 module enhances the resistance of apple to Colletotrichum gloeosporioides by promoting lignin synthesis in response to salicylic acid signalling.

Apple is an important cash crop in China, and it is susceptible to fungal infections that have deleterious effects on its yield. Apple bitter rot caused by Colletorichum gloeosporioides is one of the most severe fungal diseases of apple. Salicylic acid (SA) is a key signalling molecule in the plant disease resistance signalling pathways. Lignin synthesis also plays a key role in conferring disease resistance. However, few studies have clarified the relationship between the SA disease resistance signalling pathway and the lignin disease resistance pathway in apple. MdMYB46 has previously been shown to promote lignin accumulation in apple and enhance salt and osmotic stress tolerance. Here, we investigated the relationship between MdMYB46 and biological stress; we found that MdMYB46 overexpression enhances the resistance of apple to C. gloeosporioides. We also identified MdARF1, a transcription factor upstream of MdMYB46, via yeast library screening and determined that MdARF1 was regulated by miR7125 through psRNATarget prediction. This regulatory relationship was confirmed through LUC and qRT-PCR experiments, demonstrating that miR7125 negatively regulates MdARF1. Analysis of the miR7125 promoter revealed that miR7125 responds to SA signals. The accumulation of SA level will result in the decrease of miR7125 expression level. In sum, the results of our study provide novel insights into the molecular mechanisms underlying the resistance of apple to C. gloeosporioides and reveal a new pathway that enhances lignin accumulation in apple in response to SA signals. These findings provide valuable information for future studies aimed at breeding apple for disease resistance.

A Comprehensive Review of Sclerotinia Stem Rot in Indian Mustard (Brassica juncea)

Indian mustard (Brassica juncea), an important oilseed crop, is highly susceptible to the devastating disease called Sclerotinia stem rot, caused by the fungus Sclerotinia sclerotiorum. This review paper provides a comprehensive summary of the present understanding of the disease, encompassing its epidemiology, pathogen biology, interactions between the host and pathogen, management strategies, and the latest advancements in research. There is an urgent need for effective disease management strategies, as evident by the financial consequences of Sclerotinia stem rot on the production of Indian mustard. This review aims to comprehensively analyze research articles to enhance our understanding of the disease and expedite the development of enduring solutions to mitigate it's impacts. Rapeseed mustard is susceptible to various pathogens, including fungi, bacteria, viruses, and phytoplasma. Sclerotinia stem rot is the most severe fungal disease affecting Indian mustard. Extensive studies and development have been conducted on the occurrence of Sclerotinia rot in rapeseed mustard. This study examines these endeavors in relation to disease cycle, epidemiology, pathogen taxonomy, nature, and control. Moreover, the study aims to present a comprehensive summary of potential future goals and research methodologies concerning Sclerotinia rot in rapeseed.

Biosynthesis of Scopoletin in Sweet Potato Confers Resistance against Fusarium oxysporum.

Fusarium wilt is a severe fungal disease caused by Fusarium oxysporum in sweet potato. We conducted transcriptome analysis to explore the resistance mechanism of sweet potato against F. oxysporum. Our findings highlighted the role of scopoletin, a hydroxycoumarin, in enhancing resistance. In vitro experiments confirmed that scopoletin and umbelliferone had inhibitory effects on the F. oxysporum growth. We identified hydroxycoumarin synthase genes IbF6'H2 and IbCOSY that are responsible for scopoletin production in sweet potatoes. The co-overexpression of IbF6'H2 and IbCOSY in tobacco plants produced the highest scopoletin levels and disease resistance. This study provides insights into the molecular basis of sweet potato defense against Fusarium wilt and identifies valuable genes for breeding wilt-resistant cultivars.

Evaluating Pomegranate Cultivars for Resistance to Anthracnose Fruit Rot, a Severe Fungal Disease in Florida and Southeast United States

Pomegranate (Punica granatum L.) has primarily been cultivated at home in Florida and other southeastern states. Over the past 15 years, growers, nurseries, researchers, and Extension agents have explored the potential of pomegranate as an alternative fruit crop. Early field trials revealed that pomegranates are highly susceptible to Colletotrichum gloeosporioides, causing severe anthracnose fruit rot and premature fruit drop. The development and use of disease-resistant cultivars are considered some of the best methods to manage this disease. This publication presents our findings from evaluating 35 pomegranate cultivars under natural disease pressure in central Florida and by artificial inoculation. The susceptibility of such pomegranate cultivars varied widely, with six exhibiting resistance to anthracnose fruit rot. More comprehensive research is warranted to further develop anthracnose-resistant cultivars and to enhance our understanding of disease resistance in this crop.

Fine mapping of ClLOX, a QTL for powdery mildew resistance in watermelon (Citrullus lanatus L.).

ClLOX, is located on chromosome 2 and encodes a lipoxygenase gene, which induced watermelon powdery mildew resistance by inhibiting pathogen spread. Powdery mildew is one of the most severe fungal diseases reducing yield and quality of watermelon (Citrullus lanatus L.) and other cucurbit crops. Genes responsible for powdery mildew resistance in watermelon are highly valuable. In this study, we first identified the QTL pm-lox for powdery mildew resistance in watermelon, located within a 0.93Mb interval of chromosome 2, via XP-GWAS method using two F2 populations. The F2:3 families from one of the F2 populations were then used for fine-mapping the pm-lox locus into a 9,883bp physical region between 29,581,906 and 29,591,789, containing only two annotated genes. Of these, only ClG42_02g0161300 showed a significant differential expression between the resistant and susceptible lines after powdery mildew inoculation based on RNA sequencing (RNA-seq) and qRT-PCR analysis, and is designated ClLOX. Derived Cleaved Amplified Polymorphic Sequence (dCAPs) markers were developed and validated. In addition, our tests showed that the resistance was anti-spread rather than anti-infection of the pathogen. This study identified a new resistance gene (ClLOX), provided insights into the mechanism of powdery mildew resistance, and developed a molecular marker for watermelon breeding.

Incidence and severity of fungal seedling diseases in Tamale central forest nursery, Ghana

Fungal diseases cause serious seedling mortality in nurseries and threaten future seedling production for forest regeneration. To abate this menace, knowledge about them is key. Therefore, this study aimed at determining the incidence and severity of fungal diseases of forest seedlings in the Central Forest Nursery of Tamale, Ghana. Khaya senegalensis, Tectona grandis and Polyalthia longifolia in the nursery were infected with eight fungal pathogens and an unidentified fungus causing leaf blight, wilt, and dumping-off diseases. The pathogens included Rhizoctonia sp., Fusarium sp., Corrynespora sp., Colletotrichum sp., Cercospora sp., Phytophthora sp., Chaetomium sp., and Macrophomina sp. Rhizoctonia was the dominant pathogen isolated from all the leaves of the seedling species. Colletotrichum and Chaetomium were isolated from the leaves of Polyalthia longifolia. Cercospora and an unidentified spp. were found on the stems of Tectona grandis. Fusarium and Phytophthora were respectively found on Polyalthia longifolia and Khaya senegalensis stems. Chaetomium was identified on both Polyalthia longifolia and Khaya senegalensis stems. Cercospora and Fusarium were isolated from the roots of Tectona grandis and Polyalthia longifolia respectively while Macrophomina was associated with both Tectona grandis and Khaya senegalensis roots. Leaf blight recorded the highest disease incidence (76.7%) and affected all the three seedling species. Wilt disease showed low incidence (10.2-15.8 %) among the different seedling species. Dumping-off disease incidence (10.4%) was only recorded in Khaya senegalensis. The severities of the diseases identified were low (1-2) score except leaf blight of Tectona grandis and Polyalthia longifolia recording a moderate (3.0) severity score. It is recommended that appropriate disease management strategies be employed to prevent high incidences and severities.

Non-destructive detection of fusarium head blight in wheat kernels and flour using visible near-infrared and mid-infrared spectroscopy

Fusarium head blight (FHB) is one of the most severe fungal diseases that reduces yield of cereal crops and degrades kernel quality with mycotoxins, which are harmful to human and animal health. The majority of FHB identification at post-harvest stage is through lab-based analysis, whilst effective it is a time consuming, expensive, and laborious process. Hence, a non-destructive, rapid, accurate, and robust method is required for FHB detection at post-harvest. This study explores the potential of visible near-infrared (vis-NIR) in the wavelength range from 400 to 1700 nm and the mid-infrared (MIR) in the wavenumber range from 4000 to 650 cm−1 to predict FHB infection of wheat kernels and flour. A total of 143 ear samples (93 infected, and 50 healthy) were collected from an inoculated trial covering several winter wheat varieties. The collected spectral data was analysed with two different machine learning algorithms, namely, random forest (RF) and linear discriminant analysis (LDA). Both models produced a higher test accuracy of 96.6 % and 100 %, respectively, for the flour samples than that (e.g., 93.1 %) for the kernels, using the MIR spectroscopy. Recursive feature elimination (RFE) demonstrated notable improvements in accuracy of the vis-NIR for the kernels, with LDA model providing 100 % classification accuracy. While RFE failed to improve the accuracy of MIR-LDA models. The results highlight the effectiveness of vis-NIR and MIR spectroscopy with RFE and machine learning for classifying FHB in wheat kernel and flour samples.

Identification of novel sources of partial and incomplete hypersensitive resistance to rust and associated genomic regions in common bean

Common bean (Phaseolus vulgaris) is one of the legume crops most consumed worldwide and bean rust is one of the most severe foliar biotrophic fungal diseases impacting its production. In this work, we searched for new sources of rust resistance (Uromyces appendiculatus) in a representative collection of the Portuguese germplasm, known to have accessions with an admixed genetic background between Mesoamerican and Andean gene pools. We identified six accessions with incomplete hypersensitive resistance and 20 partially resistant accessions of Andean, Mesoamerican, and admixed origin. We detected 11 disease severity-associated single-nucleotide polymorphisms (SNPs) using a genome-wide association approach. Six of the associations were related to partial (incomplete non-hypersensitive) resistance and five to incomplete hypersensitive resistance, and the proportion of variance explained by each association varied from 4.7 to 25.2%. Bean rust severity values ranged from 0.2 to 49.1% and all the infection types were identified, reflecting the diversity of resistance mechanisms deployed by the Portuguese germplasm.The associations with U. appendiculatus partial resistance were located in chromosome Pv08, and with incomplete hypersensitive resistance in chromosomes Pv06, Pv07, and Pv08, suggesting an oligogenic inheritance of both types of resistance. A resolution to the gene level was achieved for eight of the associations. The candidate genes proposed included several resistance-associated enzymes, namely β-amylase 7, acyl-CoA thioesterase, protein kinase, and aspartyl protease. Both SNPs and candidate genes here identified constitute promising genomics targets to develop functional molecular tools to support bean rust resistance precision breeding.