Muthusamy Karthikeyan

Ustiloxins are toxic cyclic peptides produced by the rice false smut fungus Ustilaginoidea virens . False smut disease turns rice grains into yellow‐orange spores later turned into greenish‐black smut balls, significantly reducing yield and grain quality. Due to their hydrophilic nature ustiloxins leach from spore balls and contaminate paddy soil, water, and rice products. They block eukaryotic cell division by binding tubulin and inhibit microtubule polymerization. This review provides information on advances in ustiloxin biology and control. It summarizes ribosomally synthesized and post‐translationally modified peptides (RiPPs) biosynthesis and recent insights into pathway genes, regulatory networks including target of rapamycin (TOR) signaling, and comparative fungal genomics. Environmental occurrence is reviewed with emphasis on persistence in soil, water and translocation into rice grains. Ecotoxicological evidence is consolidated, spanning phytotoxicity, effects on beneficial microbes, aquatic organisms, and mammalian toxicity supported by in vivo and mechanistic studies. Progress in detection is outlined with improved LC–MS/MS, immunoassays, and emerging biosensors for field diagnostics. Management strategies are evaluated, including resistant cultivars, disease forecasting, fungicidal and biological controls, and post‐harvest detoxification via enzymatic and physical approaches. A dedicated risk assessment discusses human dietary exposure, regulatory status, and the need for maximum limits. The review concludes by highlighting research priorities such as multi‐omics, spread modeling, and biotechnological interventions, to close key knowledge gaps and enable effective monitoring and mitigation toward an ustiloxin‐free rice agroecosystem.

Plant pathogens pose persistent threats to global food production, driving the need for sustainable and effective disease management strategies. While the use of chemical pesticides is the primary control measure adopted, their environmental toxicity has raised concerns, prompting extensive research into the development of eco-friendly alternatives. Nanotechnology has emerged as a promising and sustainable tool for plant protection. The biopolymer chitosan is well-known for its unique physicochemical properties including biodegradability, biocompatibility and low toxicity, making it one of the most reliable polymers for nanoformulation development. These formulations, including nanoparticles and nanocomposites, incorporate chitosan as an antimicrobial nanomaterial as well as a carrier forother biocidal nano-substances offering an efficient solution against plant diseases. Chitosan as a carrier enhances the targeted delivery of the encapsulated substances through their slow and controlled release. The nanoformulations adopt multiple modes of action to combat pathogens, which include membrane disruption, inhibition of growth and biofilm formation and induction of defence responses within the plant. This review elucidates the advantages of using chitosan for fabricating novel nanoformulations for plant protection. Their superior modes of action against fungi, bacteria, viruses and nematodes have also been highlighted alongside challenges such as stability and scalability, thus paving the way for their integration into sustainable pest management systems.

Carbendazim, a benzimidazole fungicide, is widely used for the management of fungal diseases in agricultural systems; however, the emergence of resistant fungal populations has raised concerns regarding its long-term effectiveness. The present study evaluated the baseline sensitivity of selected pathogenic and beneficial fungi - Colletotrichum capsici, Rhizoctonia solani, Agroathelia rolfsii, Pleurotus sajor-caju, and Trichoderma viride - to carbendazim using in vitro assays. Sensitivity was assessed through mycelial growth inhibition, EC₅₀ estimation, biomass reduction, and stability of resistance across successive generations. The results revealed considerable variability among the tested fungi. R. solani and T. viride showed high sensitivity to carbendazim with low EC₅₀ values, whereas C. capsici, P. sajor-caju, and A. rolfsii exhibited reduced sensitivity and sustained growth even at higher fungicide concentrations, indicating potential resistance development. Repeated subculturing under fungicide pressure further confirmed the stability of tolerance in these isolates. To explore possible target-site interactions, molecular docking analysis was performed between carbendazim and β-tubulin proteins of the tested fungi, revealing variations in binding affinity that may contribute to differences in fungicide sensitivity. In addition, metabolite profiling using GC-MS demonstrated distinct biochemical shifts between control and carbendazim-treated cultures, indicating metabolic adaptation under fungicide stress. The combined findings suggest that carbendazim resistance in fungi may involve both target-site interactions and metabolic adjustments. This study provides baseline sensitivity data and mechanistic insights that can support resistance monitoring and guide the development of more sustainable fungicide management strategies.

Blast disease caused by Pyricularia species is a significant constraint in millets and rice worldwide. The present research attempted at studying the occurrence, isolation and identification of blast pathogen, with attention on the systematic position in the Pyricularia spp. complex and host-related pathotypes. To differentiate between genera and assess host specificity, internal transcribed spacer (ITS) related phylogenetic analysis has been used. During the 2024–2025 cropping seasons, a field assessment was carried out in Tamil Nadu millet and rice-growing districts as well as in a few locations in Andhra Pradesh. Leaf samples exhibiting typical blast symptoms was collected. Fifty blast isolates isolated by standard tissue isolation on potato dextrose agar (PDA) were purified using the single-spore isolation method. Morphological analysis showed a significant variance between the isolates with radial mycelial growth ranging from 62–89 mm with plate cover in 10–16 days. The typical pyriform, 3 celled conidia of Pyricularia spp. are produced by abundant sporulation in colony which vary in colour from grey to olivaceous. Detached-leaf inoculation revealed typical spindle-shaped lesions within 3–6 days after inoculation (DAI). Pearl millet isolates were most virulent (0.14–1.38 cm²; MgPM1 highest), followed by barnyard millet (0.04–0.48 cm²; MgBM3), while finger millet (0.06–0.21 cm²; MgFM4) and foxtail millet (0.02–0.18 cm²; MgFoxM3) showed lower virulence. The ITS-based molecular identification yielded ~560 bp amplicons, with 92–100 % similarity to Pyricularia spp. In the National Centre for Biotechnology Information (NCBI) GenBank, confirming identity. However, ITS lacked resolution for species and pathotype differentiation, requiring further phylogenetic and pathogenicity analysis.

Cabbage head rot, caused by Sclerotinia sclerotiorum , threatens crop yield and quality. Among the 21 mycoparasitic fungi isolated from sclerotia, dormant structure and primary sources of inoculum for the pathogen, the strongest antagonism (78.51% mycelial growth inhibition) was observed in Paraphaeosphaeria minitans strain TNAU‐CM 1. Scanning electron microscopy (SEM) revealed its destructive colonisation, including pycnidia and pycnidiospore formation, with visible shrinkage and deformation of sclerotia. Gas chromatography–mass spectrometry (GC–MS) analysis identified 24 bioactive metabolites at the point of interactions between P. minitans TNAU‐CM 1 and S. sclerotiorum TNAU‐SS‐5 strains in dual‐culture assays. Further, crude metabolites from P. minitans TNAU‐CM 1 cultures inhibited the pathogen's mycelial growth by 54.4% at 100 ppm. In the molecular docking of 14 key compounds, linoleic acid and butyl octyl phthalate, well‐known antifungal compounds, displayed the highest binding affinity of −7.6 and −6.2 kcal/mol, respectively, against Saccharomyces cerevisiae cupin protein (1ZNP) YML079w, a homologue of SsYCP1, a YML079‐like cupin protein (YCP) and a virulence molecule from S. sclerotiorum . Field trials demonstrated that foliar application of P. minitans TNAU‐CM 1 stock solution (8–10 × 10 ⁸ spores per mL) at 5 mL/L dilutions significantly reduced disease incidence and the crops produced a yield of 41.37 tons/ha, comparable to chemical fungicide treatment (43.51 tons/ha). Thus, molecular interaction studies and field evaluations suggest that P. minitans TNAU‐CM 1 is a promising eco‐friendly alternative to synthetic fungicides for the management of cabbage head rot. Furthermore, our findings indicate that linoleic acid and butyl octyl phthalate are the key antifungal metabolites of P. minitans , active against S. sclerotiorum and will serve as potential candidates for developing bio‐fungicide formulations to control head rot in cabbage.