Sclerotia Formation Research Articles

First characterization of a newly emerging phytopathogen, Sclerotinia sclerotiorum causing white mold in pea.

Pea (Pisum sativum L.) is of global importance as a food crop for its edible pod and seed. A new disease causing the tan to light brown blighted stems and pods has occurred in pea (P. sativum L.) plants in Chapainawabganj district, Bangladesh. A fungus with white-appressed mycelia and large sclerotia was consistently isolated from symptomatic tissues. The fungus formed funnel-shaped apothecia with sac-like ascus and endogenously formed ascospores. Healthy pea plants inoculated with the fungus produced typical white mold symptoms. The internal transcribed spacer sequences of the fungus were 100% similar to Sclerotinia sclerotiorum, considering the fungus to be the causative agent of white mold disease in pea, which was the first record in Bangladesh. Mycelial growth and sclerotial development of S. sclerotiorum were favored at 20°C and pH 5.0. Glucose was the best carbon source to support hyphal growth and sclerotia formation. Bavistin and Amistar Top inhibited the radial growth of the fungus completely at the lowest concentration. In planta, foliar application of Amistar Top showed the considerable potential to control the disease at 1.0% concentration until 7 days after spraying, while Bavistin prevented infection significantly until 15 days after spraying. A large majority (70.93%) of genotypes, including tested released pea cultivars, were susceptible, while six genotypes (6.98%) appeared resistant to the disease. These results on identification, characterization, host resistance, and fungicidal control of white mold could be valuable to achieve improved management of a new disease problem for pea cultivation.

Response of Chickpea (Cicer arietinum L.) Genotypes against Collar Rot Disease Caused by Sclerotium rolfsii Sacc.

Aims: Collar rot is a fast spreading and destructive disease and is becoming more serious at seedling stage causing rot at collar region especially in area where paddy based cropping system is followed. Lack of sources of resistant in present cultivar against Sclerotium rolfsii cause serious threat to chickpea production. Therefore, the present study was carried out to evaluate the chickpea genotypes against S. rolfsii to the identification of resistant sources for further breeding program.
 Study Design: Randomized Block Design (RBD) with two replications were used.
 Place and Duration of Study: Regional Rice Research Station, Navsari Agricultural University, Vyara, between October 2019 to April 2020.
 Methodology: Pathogen was isolated from infected collar region of chickpea plant by directly transfer of sclerotia and infected bits on potato dextrose agar (PDA) medium. After purification, pathogen was identified by observed the colony character and sclerotia formation. The morphological characters viz., mycelial growth and mycelial characteristic were studied under high power magnification (40X) and sclerotia formation, shape and colour were studied under low power magnification (10X) from 10 days old culture. 39 chickpea genotypes were used for the studies. A field experiment was conducted during Rabi -2019-20 season. The inoculum was thoroughly broadcasted in soil @ 10g/ row. Germination per cent and disease incidence were observed.
 Results: Chickpea (Cicer arietinum L.) collar rot disease caused by Sclerotium rolfsii Sacc. was exhibited initial white fluffy mycelium appearance on potato dextrose agar medium. Microscopic view of mycelium was hyaline, branching, compact with septate and had a clamp connection. White sclerotia were formed after 4th days of incubation and later within 10 days after incubation it became mature and colour changed from brown to dark brown. Sclerotia appeared shiny due to presence of gummy material. Out of 39 chickpea genotypes only five viz., GJG-1713, GG-6, GJG-1509, Phule Vikram and JGK-1 were identified as moderate resistant against collar rot disease caused by S. rolfsii under inoculums inoculated rice fellow cropping system.
 Conclusion: Chickpea genotypes viz., GJG-1713, GG-6, GJG-1509, Phule Vikram and JGK-1 were showed moderate resistant reaction against collar rot disease caused by S. rolfsii.

Functional dissection of individual domains in group III histidine kinase Sshk1p from the phytopathogenic fungus Sclerotinia sclerotiorum

A conserved kinase domain and phosphoryl group receiver domain at the C-terminus and poly-HAMP domains at the N-terminus comprise the structural components of the group III HK which was considered as a potential antifungal target. However, the roles of individual domains in the function of group III HKs have rarely been dissected in fungi. In this study, we dissected the roles of individual domains to better understand the function of Sshk1p, a group III HK from Sclerotinia sclerotiorum. The results suggest that individual domains play different roles in the functionality of Sshk1p and are implicated in the regulation of mycelial growth, sclerotia formation, pathogenicity. And the mutants of each domain in Sshk1 showed significantly increased sensitivity to hyperosmotic stress. However, the mutants of each domain in Sshk1 showed high resistance to fludioxonil and dimethachlon which suggested that all nine domains of Sshk1p were indispensable for susceptibility to fludioxonil and dimethachlon. Moreover, deletion of each individual domain in Sshk1 cancelled intracellular glycerol accumulation and increased SsHog1p phosphorylation level triggered by NaCl and fludioxonil, suggesting that all the domains of Sshk1 were essential for Sshk1-mediated SsHog1p phosphorylation and subsequent polyol accumulation in response to fludioxonil and hyperosmotic stress.

Ras subfamily GTPases regulate development, aflatoxin biosynthesis and pathogenicity in the fungus Aspergillus flavus.

Ras subfamily proteins are molecular switches in signal transduction pathways of many eukaryotes that regulate a variety of cellular processes. Here, the Ras subfamily, encoded by six genes, was identified in Aspergillus flavus: rasA, rasB, rasC, rab-33, rheb and rsr1. The rsr1 deletion mutant (∆rsr1), rheb deletion mutant (∆rheb) and double deletion mutant (∆rheb/rsr1) displayed significantly decreased growth and sporulation. Sclerotia formation was significantly decreased for ∆rheb or ∆rheb/rsr1 but increased for ∆rsr1. Aflatoxin production was significantly increased in ∆rheb but decreased in ∆rsr1 and ∆rheb/rsr1. We found that rsr1 and rheb are crucial for the pathogenicity of A. flavus. Quantitative proteomics identified 520 differentially expressed proteins (DEPs) for the ∆rsr1 mutant and 133 DEPs for the ∆rheb mutant. These DEPs were annotated in multiple biological processes and KEGG pathways in A. flavus. Importantly, we identified the cytokinesis protein SepA in the protein-protein interaction network of rsr1, and deletion mutants showed that SepA has pleiotropic effects on growth and AF biosynthesis, which may depend on Rsr1 for regulation in A. flavus. Our results indicated that these Ras subfamily proteins exhibited functional redundancy with each other but there were also differences in A. flavus.

The PHD transcription factor Cti6 is involved in the fungal colonization and aflatoxin B1 biological synthesis of Aspergillus flavus

Aspergillus flavus and its main secondary metabolite AFB1 pose a serious threat to several important crops worldwide. Recently, it has been reported that some PHD family transcription factors are involved in the morphogenesis and AFB1 biological synthesis in A. flavus, but the role of Cti6, a PHD domain containing protein in A. flavus, is totally unknown. The study was designed to reveal the biological function of Cti6 in the fungus by deletion of cti6, and its two domains (PHD and Atrophin-1) through homologous recombination, respectively. The results showed that Cti6 might up-regulate the mycelium growth, conidiation, sclerotia formation and AFB1 biological synthesis of A. flavus by its PHD domain, while Atrophin-1 also improved the conidiation of the fungus. The qRT-PCR analysis showed that Cti6 increased the conidiation of the fungus through AbaA and BrlA mediated conidiation pathway, triggered the formation of sclerotia by orthodox sclerotia formation pathway, and improved the production of AFB1 by orthodox AFB1 synthesis pathway. Crops models analysis showed that A. flavus Cti6 plays vital role in colonization and the production of AFB1 on the host grains mainly via PHD domain. Bioinformatics analysis showed Cti6 is conservative in Aspergillus spp., and mCherry mediated subcellular localization showed that most Cti6 accumulated in the nuclei, which reflected that Cti6 performed its important biological function in the nuclei in Aspergillus spp.. The results of the current study elucidate the roles of PHD domain containing proteins in the mechanism of the infection of crops by A. flavus, and provided a novel target for effectively controlling the contamination of Aspergillus spp. to crops.

Silver nanoparticles inactivate sclerotial formation in controlling white rot disease in onion and garlic caused by the soil borne fungus Stromatinia cepivora

Silver nanoparticles inactivate sclerotial formation in controlling white rot disease in onion and garlic caused by the soil borne fungus Stromatinia cepivora

Exploring the Biological and Molecular Characteristics of Resistance to Fludioxonil in Sclerotinia sclerotiorum From Soybean in China.

Sclerotinia sclerotiorum is one of the most damaging and economically important necrotrophic plant pathogens, infecting more than 400 plant species globally. Although the phenylpyrrole fungicide fludioxonil has high activity against S. sclerotiorum, reports indicate that there is also substantial potential for the development of fungicide resistance. However, the current study investigating five fludioxonil-resistant laboratory mutants found a significant fitness cost associated with fludioxonil resistance resulting in significantly (P < 0.05) reduced mycelial growth and sclerotia formation on potato dextrose agar as well as significantly (P < 0.05) lower pathogenicity on detached tomato leaves, with one mutant, LK-1R, completely losing the capacity to cause infection. In addition, all of the fludioxonil-resistant mutants had significantly (P < 0.05) increased sensitivity to osmotic stress (0.5 M of potassium chloride and 1.0 M of glucose), which is consistent with the proposed fludioxonil target sites within the high osmolarity glycerol stress response mitogen-activated protein kinase (HOG1-MAPK) signaling transduction pathway. Sequence analysis of six genes from this two-component pathway, including SsHk, SsYpd, SsSk1, SsSk2, SsPbs, and SsHog, revealed several mutations that may be associated with fludioxonil resistance. For example, six separate point mutations were found in SsHk that led to changes in the predicted amino acid sequence, including A136G, F249V, G353A, E560K, M610K, and K727R. Similarly, SsPbs had three mutations (D34G, S46L, and L337E), SsSk1 and SsYpd had two (S53G and A795V for SsSk1, and E67G and Y141H for SsYpd), and SsHog and SsSk2 had one each (V220A and S763P, respectively). To our knowledge, these constitute the first reports of amino acid changes in proteins of the HOG1-MAPK pathway being associated with fludioxonil resistance in S. sclerotiorum. This study also showed a positive cross-resistance between fludioxonil and dimethachlone and procymidone, but none with tebuconazole or carbendazim, indicating that the inclusion of tebuconazole within an integrated pest management program could reduce the risk of fludioxonil resistance developing in field populations of S. sclerotiorum and ensure the sustainable production of soybeans in China into the future.

Comparative transcriptome analysis of cells from different areas reveals ROS responsive mechanism at sclerotial initiation stage in Morchella importuna

Morels are some of the most highly prized edible and medicinal mushrooms, with great economic and scientific value. Outdoor cultivation has been achieved and expanded on a large scale in China in recent years. Sclerotial formation is one of the most important phases during the morel life cycle, and previous reports indicated that reactive oxygen species (ROS) play an important role. However, ROS response mechanisms at sclerotial initiation (SI) stage are poorly understood. In this study, comparative transcriptome analyses were performed with sclerotial and hyphal cells at different areas in the same plate at SI stage. Gene expression was significantly different at SI stage between sclerotial formation and mycelia growth areas. GO and KEGG analyses indicated more vigorous metabolic characteristics in the hyphae area, while transcription process, DNA repair, and protein processing were enriched in sclerotial cells. Gene expression related to H2O2 production was high in the hyphae area, while expression of H2O2-scavenging genes was high in sclerotial cells, leading to a higher H2O2 concentration in the hyphal region than in the sclerotium. Minor differences were observed in gene expression of H2O2-induced signaling pathway in sclerotial and hyphal cells; however, expression levels of the target genes of transcription factor MSN2, important in the H2O2-induced signaling pathways, were significantly different. MSN2 enhanced stress response regulation in sclerotia by regulating these target genes. Small molecular HSPs were also found upregulated in sclerotial cells. This study indicated that sclerotial cells are more resistant to ROS stress than hyphal cells through transcriptional regulation of related genes.

Characterization of Cultural and Morphological Variability in Rhizoctonia solani Isolates Associated with Root Rot of Ajwain (Trachyspermum ammi L.)

Rhizoctonia solani (teleomorph: Thanatephorus spp.) is a plant pathogenic fungus which had a wide host range. It is best known to cause many diseases in plants such as collar rot, root rot, damping- off, sheath blight, stem canker, web blight and wire stem throughout the world. In vitro study of the various isolates of R. solani for morphological and cultural characters and results revealed that this experiment the various isolates of R. solani differed in colony characters and showed black brown colored cultures with 90.0 mm colony diameter on 7th day of incubation under uniform environmental condition. The highest growth reported was isolates CHIRs-5 and sclerotial formation was recorded in all the isolates of R. solani. Morphology of sclerotia varied from 1.9×1.5 mm of DCHIRs-1 and 1.8×1.5 mm of RUDPRs-2.

The antimicrobial peptide AsR416 can inhibit the growth, sclerotium formation and virulence of Rhizoctonia solani AG1-IA

Plant antimicrobial peptides (AMPs) as a part of plant defense responses, are small soluble defense molecules which can inhibit the growth of pathogens. This study evaluates the effect of an antimicrobial peptide obtained from Allium sativum (AsR416) on Rhizoctonia solani (AG1-IA) the causal agent of rice sheath blight, in vitro and in vivo conditions. Firstly, the obtained results revealed that AsR416 (100 mg ml−1) inhibited the growth and sclerotia production of R. solani AG1-IA. Furthermore, these results showed the mode of action and mechanisms of AsR416 effect in inhibiting sclerotia formation of R. solani AG1-IA via metabolomics tools. AsR416 decreased the biomass of R. solani AG1-IA in liquid culture. In addition, nitro blue tetrazolium and evans blue staining methods revealed that the antimicrobial peptide induced O2− formation in the hyphal cells and mycelia cell death of R. solani AG1-IA, respectively. AsR416 delayed the pathogen infection process and decreased the severity of rice sheath blight disease in vitro and in vivo conditions. AsR416 reduced activity of cellulase, which is one of the virulence factors of this pathogen. The number of sclerotia decreased on plants treated with AsR416 after 2 months compared with the control. Considering the need to reduce application of hazardous synthetic fungicides against pathogenic fungi, using AMPs could be a successful method to increase rice production and reduce the use of chemical fungicides against sheath blight disease.

A Putative MAPK Kinase Kinase GeneSsos4is Involved in Mycelial Growth, Virulence, Osmotic Adaptation, and Sensitivity to Fludioxonil and is Essential for SsHog1 Phosphorylation inSclerotinia sclerotiorum

The high osmolarity glycerol (HOG) pathway, comprising a two-component system and the Hog1 mitogen-activated protein kinase (MAPK) cascade, plays a pivotal role in eukaryotic organisms. Previous studies suggested that the biological functions of some key genes in the HOG pathway varied in filamentous fungi. In this study, we characterized a putative MAPK kinase kinase gene, Ssos4, in Sclerotinia sclerotiorum, which encoded a phosphotransferase in the MAPK cascade. Compared with the wild-type progenitor HA61, the deletion mutant ∆Ssos4-63 exhibited impaired mycelial growth, sclerotia formation, increased hyphal branches, and decreased virulence. The deficiencies of the deletion mutant ∆Ssos4-63 were recovered when the full-length Ssos4 gene was complemented. Deletion of Ssos4 increased the sensitivity to osmotic stresses and cell wall agents and the resistance to fludioxonil and dimethachlon. Intracellular glycerol accumulation was not induced in the deletion mutant ∆Ssos4-63 when treated with fludioxonil and NaCl and the phosphorylation of SsHog1 was also cancelled by the deletion of Ssos4. Consistent with the glycerol accumulation and increased expression levels of SsglpA and Ssfps1, controlling glycerol synthesis and close of glycerol channel under hyperosmotic stress, respectively, were detected in the wild-type strain HA61 but not in the deletion mutant ∆Ssos4-63. Moreover, the relative expression level of Sshog1 significantly decreased, whereas the expression level of Ssos5 increased in the deletion mutant ∆Ssos4-63. These results indicated that Ssos4 played important roles in mycelial growth and differentiation, sclerotia formation, virulence, hyperosmotic adaptation, fungicide sensitivity, and the phosphorylation of SsHog1 in S. sclerotiorum.

Synthetic antimicrobial agents inhibit aflatoxin production.

Antimicrobial peptides (AMPs) are biologically active molecules that can eradicate bacteria by destroying the bacterial membrane structure, causing the bacteria to rupture. However, little is known about the extent and effect of AMPs on filamentous fungi. In this study, we synthesized small molecular polypeptides by an inexpensive heat conjugation approach and examined their effects on the growth of Aspergillus flavus and its secondary metabolism. The antimicrobial agents significantly inhibited aflatoxin production, conidiation, and sclerotia formation in A. flavus. Furthermore, we found that the expression of aflatoxin structural genes was significantly inhibited, and the intracellular reactive oxygen species (ROS) level was reduced. Additionally, the antimicrobial agents can change membrane permeability. Overall, our results demonstrated that antimicrobial agents, safe to mammalian cells, have an obvious impact on aflatoxin production, which indicated that antimicrobial agents may be adopted as a new generation of potential agents for controlling aflatoxin contamination.

Development of New Strains of Wolfiporia cocos for Sclerotium Formation by 2-Way Cross-Breeding

Development of New Strains of Wolfiporia cocos for Sclerotium Formation by 2-Way Cross-Breeding

Sclerotinia sclerotiorum KK-1 isolate from Belarus: pathogenicity factors and glyphosate sensitivity

In the presence work, mycelial growth, sclerotia formation, polygalacturonase, a-amylase and cellulase activities of a Belarusian fungal isolate Sclerotinia sclerotiorum KK-1 collected from infected сarrot (Daucus carota subsp. sativus) were analyzed. It was established that polygalacturonase was induced by pectin and subject to catabolite repression by glucose. The ability of the isolate to produce oxalic acid, an important factor of pathogenesis, was observed throughout fungus incubation on PDA medium amended with bromophenol blue. Glyphosate (commercial counterpart «Tornado») starting from its level in the medium of 200 mg/L caused a significant inhibition of mycelial growth and sclerotia formation. It was observed that a-amylase and cellulase activities were inhibited by glyphosate unlike polygalacturonase activity.

Use of non-chemical methods for the management of southern blight disease of carrot incited by Sclerotium rolfsii

This experiment was conducted to assess the effect of Trichoderma harzianum, soil solarization, and biofumigant on southern blight dis-ease of carrot incited by Sclerotium rolfsii isolate CS 5. A series of in-vitro and in-vivo trials laid out to select a virulent isolate of S. rolfsii against the carrot variety New Kuroda and evaluated the mustard, cabbage, cauliflower, and broccoli leaf extracts for choosing an effec-tive biofumigant against test pathogen. Mustard was the most effec-tive in inhibiting the radial growth, and sclerotia formation (80.37 and 83.37%) of S. rolfsii (isolate CS 5) at 40% level of concentration followed by cabbage leaf extract (62.22 and 68.69%). On the contrary, a total of 10 isolates of T. harzianum were screened against the test pathogen on Potato Dextrose Agar (PDA) medium for choosing a dominant isolate of T. harzianum. The isolate Th-6 was found as the most active in inhibiting the radial growth (84.44%) of S. rolfsii fol-lowed by Th-1 (75.56%). In the application of T. harzianum, biofumi-gation, and soil solarization, the treatment appeared to be the most superior in reducing pre- and post-emergence mortality of carrot during secondary field trials. The lowest southern blight disease inci-dence (10.77%), and disease severity (12.78%) were found at the same treatment. Subsequently, the yield of carrot was increased 155.18% which might be due to the reduction of carrot disease as well as the addition of organic materials in the soil.

Identification and Characterization of White Mold Disease (Sclerotinia sclerotiorum) in Globe Artichoke

Globe artichoke ( Cynara scolymus L.) is an economically important plant that is cultivated over 30 countries in the world. In 2017, wilting and lodging symptoms were observed on globe artichoke plants in three locations (Serik-Gebiz, Serik-Karadayi and Gazipasa-Bakilar) in the Western Mediterranean Region of Turkey. To determine the cause of the symptoms, samples from necrotic tissues were cultured in vitro. Based on the morphological and ITS sequences, the causal agent was identified as Sclerotinia sclerotiorum (Lib.) de Bary. Pathogenicity test was conducted using cv. Bayrampasa in the greenhouse. Three isolates (Ser3, Ser4 and Gzp3) of S . sclerotiorum were characterized on the basis of mycelial compatibility, colony radial growth, sclerotia formation, sclerotia size, sclerotia weight and sclerotia number. Virulence of the isolates was also determined using detached leaf technique. No mycelial compatibility was detected among the isolates. Significant (P<0.01) differences were found in the examined morphological features and virulence of the isolates. Gzp3 was the most virulent isolate forming average 8.60 cm lesion length. However, lesion lengths formed by the other isolates, Ser3 and Ser4, were average 4.16 and 1.93 cm, respectively. This is the first detailed characterization of S . sclerotiorum causing crown and stalk rot in globe artichoke.

The Conserved MAP Kinase MpkB Regulates Development and Sporulation without Affecting Aflatoxin Biosynthesis in Aspergillus flavus.

In eukaryotes, the MAP kinase signaling pathway plays pivotal roles in regulating the expression of genes required for growth, development, and stress response. Here, we deleted the mpkB gene (AFLA_034170), an ortholog of the Saccharomyces cerevisiae FUS3 gene, to characterize its function in Aspergillus flavus, a cosmopolitan, pathogenic, and aflatoxin-producing fungus. Previous studies revealed that MpkB positively regulates sexual and asexual differentiation in Aspergillus nidulans. In A. flavus, mpkB deletion resulted in an approximately 60% reduction in conidia production compared to the wild type without mycelial growth defects. Moreover, the mutant produced immature and abnormal conidiophores exhibiting vesicular dome-immaturity in the conidiophore head, decreased phialide numbers, and very short stalks. Interestingly, the ΔmpkB mutant could not produce sclerotia but produced aflatoxin B1 normally. Taken together, these results suggest that the A. flavus MpkB MAP kinase positively regulates conidiation and sclerotia formation but is not involved in the production of secondary metabolites such as aflatoxin B1.

Some Plants Showing Antagonism to Five Plant Pathogenic Fungi

Fungi are among the main agents of plant diseases, being responsible for major losses in agriculture. The control of these microorganisms carried out using chemical compounds and numerous cases of resistance have already been observed, which makes it necessary to search for alternative methods of management of these pathogens. Therefore, the aim of this study, to evaluate the antifungal potential in plants. Twenty-four (24) plant extracts were tested for their antifungal potential against five plant pathogenic fungi: Sclerotinia sclerotiorum (Ss), Stromatinia cepivora (Sc), Fusarium oxysporum (Fox), Colletotrichum gloesporioides (Cg) and Verticillium dahlia (Vd). For the evaluation of the fungicidal potential, plant extracts were prepared by liquefying the plants in distilled water. The extracts were incorporated into PDA (Potato-Dextrose-Agar) culture medium to a final concentration of 35% and autoclaved. Then, PDA discs colonized by the aforementioned fungi were added to the center of each plate with the respective treatments (plant extracts). When all control treatments (PDA medium without plant extract) had colonized the entire Petri dish, the diameters of the fungal colonies were measured to calculate the Mycelial Growth Inhibition Index (MGI). Tests showed that all these plant extracts have some antifungal activity, ranging from 0 to 100% inhibition. In general, extracts of basil, lavender, guaco, rue, toxic cassava and black plum were the ones that stood out, with MGIs above 50%. New studies are being conducted to evaluate the activity of plant extracts without autoclaving, inhibition of sclerotia formation, to determine the minimum inhibitory concentration, as well as other parts of plants like roots and seeds, mixtures of plant extracts and in vivo antagonism tests.

Ssu72 Regulates Fungal Development, Aflatoxin Biosynthesis and Pathogenicity in Aspergillus flavus

The RNA polymerase II (Pol II) transcription process is coordinated by the reversible phosphorylation of its largest subunit-carboxy terminal domain (CTD). Ssu72 is identified as a CTD phosphatase with specificity for phosphorylation of Ser5 and Ser7 and plays critical roles in regulation of transcription cycle in eukaryotes. However, the biofunction of Ssu72 is still unknown in Aspergillus flavus, which is a plant pathogenic fungus and produces one of the most toxic mycotoxins-aflatoxin. Here, we identified a putative phosphatase Ssu72 and investigated the function of Ssu72 in A. flavus. Deletion of ssu72 resulted in severe defects in vegetative growth, conidiation and sclerotia formation. Additionally, we found that phosphatase Ssu72 positively regulates aflatoxin production through regulating expression of aflatoxin biosynthesis cluster genes. Notably, seeds infection assays indicated that phosphatase Ssu72 is crucial for pathogenicity of A. flavus. Furthermore, the Δssu72 mutant exhibited more sensitivity to osmotic and oxidative stresses. Taken together, our study suggests that the putative phosphatase Ssu72 is involved in fungal development, aflatoxin production and pathogenicity in A. flavus, and may provide a novel strategy to prevent the contamination of this pathogenic fungus.

The Destructive Fungal Pathogen Botrytis cinerea-Insights from Genes Studied with Mutant Analysis.

Botrytis cinerea is one of the most destructive fungal pathogens affecting numerous plant hosts, including many important crop species. As a molecularly under-studied organism, its genome was only sequenced at the beginning of this century and it was recently updated with improved gene annotation and completeness. In this review, we summarize key molecular studies on B. cinerea developmental and pathogenesis processes, specifically on genes studied comprehensively with mutant analysis. Analyses of these studies have unveiled key genes in the biological processes of this pathogen, including hyphal growth, sclerotial formation, conidiation, pathogenicity and melanization. In addition, our synthesis has uncovered gaps in the present knowledge regarding development and virulence mechanisms. We hope this review will serve to enhance the knowledge of the biological mechanisms behind this notorious fungal pathogen.