Aflatoxin, a type of mycotoxin, is mostly produced by Aspergillus flavus and Aspergillus parasiticus. It is responsible for the loss of billions of dollars to the world economy, by contaminating different crops such as cotton, groundnut, maize, and chilies, and causing immense effects on the health of humans and animals. More than eighteen different types of aflatoxins have been reported to date, and among them, aflatoxins B1, B2, G1, and G2 are the most prevalent and lethal. Early detection of fungal infection plays a key role in the control of aflatoxin contamination. Therefore, different methods, including culture, chromatographic techniques, and molecular assays, are used to determine aflatoxin contamination in crops and food products. Many countries have set a maximum limit of aflatoxin contamination (2–20 ppb) in their food and agriculture commodities for human or animal consumption, and the use of different methods to combat this menace is essential. Fungal infection mostly takes place during the pre- and post-harvest stage of crops, and most of the methods to control aflatoxin are employed for the latter phase. Studies have shown that if correct measures are adopted during the crop development phase, aflatoxin contamination can be reduced by a significant level. Currently, the use of bio-pesticides is the intervention employed in many countries, whereby atoxigenic strains competitively reduce the burden of toxigenic strains in the field, thereby helping to mitigate this problem. This updated review on aflatoxins sheds light on the sources of contamination, and the on occurrence, impact, detection techniques, and management strategies, with a special emphasis on bio-pesticides to control aflatoxins.

Generally, soils in Pakistan are deficient in P and N. Due to intensive cropping and irrigation, Pakistani soils have also become deficient in micronutrients such as Zn, Fe, Cu, and Mn. Arbuscular mycorrhizal fungi, which form symbiotic associations with roots of most land plants, are known to enhance uptake of P and trace elements such as Cu, Ni, Pb, and Zn. The present study was conducted to investigate the role of arbuscular mycorrhizae (AM) in uptake of nickel (Ni) and zinc (Zn) by crops viz. soybean (Glycine max (L.) Merrill) and lentil (Lens culinaris Medic). Zn and Ni were applied as ZnSO₄ 7H₂O and NiCl₂ respectively, in four concentrations (0.0, 1.0, 3.0, and 5.0 g kg^-1 soil). AM inoculum consisted of sand containing sporocarps, spores, and AMF infected root pieces from a pot culture of Glomus mosseae. Control plants received pot culture filtrate containing soil microflora minus AM fungal propagules. A significant difference (p < 0.05) was observed in the dry weights of roots and shoots of the mycorrhizal (M) and nonmycorrhizal (NM) cereal plants. The sievate-amended treatments did not stimulate plant growth to the same extent as the AM fungal amended treatments. Trace metals inhibited the extent of mycorrhizal colonization of the cereal roots. The concentrations of the trace metals in the plant tissues of 12-week old cereal plants were found significantly (p < 0.05) higher in M than NM plants. These results indicate that mycorrhize can be used as effective tools to supply sufficient Zn in generally Zn-deficient Pakistani soils and to ameliorate the toxicity of trace metals in polluted soils. The contents of Ni in mycorrhizal soybean plant tissues were higher than those in the mycorrhizal lentil plant tissues. The implications of these results in mycorrhizo remediation of agricultural soils are discussed.

Summary: To reveal mycovirus diversity, we conducted a search of as‐yet‐unexplored Mediterranean isolates of the phytopathogenic ascomycete Rosellinia necatrix for virus infections. Of seventy‐nine, eleven fungal isolates tested RNA virus‐positive, with many showing coinfections, indicating a virus incidence of 14%, which is slightly lower than that (approximately 20%) previously reported for extensive surveys of over 1000 Japanese R. necatrix isolates. All viral sequences were fully or partially characterized by Sanger and next‐generation sequencing. These sequences appear to represent isolates of various new species spanning at least 6 established or previously proposed families such as Partiti‐ , Hypo‐, Megabirna‐ , Yado‐kari‐, Fusagra‐ and Fusarividae, as well as a newly proposed family, Megatotiviridae. This observation greatly expands the diversity of R. necatrix viruses, because no hypo‐, fusagra‐ or megatotiviruses were previously reported from R. necatrix . The sequence analyses showed a rare horizontal gene transfer event of the 2A‐like protease domain between a dsRNA (phlegivirus) and a positive‐sense, single‐stranded RNA virus (hypovirus). Moreover, many of the newly detected viruses showed the closest relation to viruses reported from fungi other than R. necatrix , such as Fusarium spp., which are sympatric to R. necatrix . These combined results imply horizontal virus transfer between these soil‐inhabitant fungi.

Fungi collectively host various RNA viruses. Examples include encapsidated double-stranded RNA (dsRNA) viruses with diverse numbers of genomic segments (from 1 to 12) and capsidless viruses with nonsegmented (+)RNA genomes. Recently, viruses with unusual intermediate features of an infectious entity between encapsidated dsRNA viruses and capsidless (+)RNA viruses were found. They are called polymycoviruses, which typically have four to eight dsRNA genomic segments associated with one of the virus-encoded proteins and are phylogenetically distantly related to animal (+)RNA caliciviruses. Here, we identified a novel virus phylogenetically related to polymycoviruses, from the phytopathogenic fungus Fusarium oxysporum . The virus, termed Hadaka virus 1 (HadV1), has 11 (+)RNA genomic segments, the largest number in known (+)RNA viruses. Nevertheless, HadV1 lacked a typical structural protein of polymycoviruses and was not pelleted by standard ultracentrifugation, implying an unusual capsidless nature of HadV1. This study reveals a potential novel lifestyle of multisegmented RNA viruses.

Significance: RNAi-mediated antiviral defense is well conserved in eukaryotic organisms. Although several RNAi key genes are transcriptionally up-regulated upon virus infection in many hosts, little is known about their induction mechanism. Here, we developed a screening method for identification of the genes mediating robust transcriptional up-regulation upon infection by RNA viruses of the dicer-like 2 ( dcl2 ) gene of an ascomycetous phytopathogen, chestnut blight fungus. We show that two enzymatic activities of histone acetyltransferase and histone deubiquitinase of the universally conserved SAGA (Spt–Ada–Gcn5 acetyltransferase) complex differentially regulate the transcriptional induction of two main antiviral RNA silencing components, dcl2 and argonaute-like 2 ( agl2 ). A virus-specific pattern requirement of AGL2 and DCL2 as positive feedback players for this transcriptional induction is also noted.