Wheat blast is a devastating fungal disease caused by a filamentous fungus, Magnaporthe oryzae Triticum (MoT) pathotype, which poses a serious threat to food security of South America and South Asia. In the course of screening novel bioactive secondary metabolites, we found that some secondary metabolites from a marine Bacillus subtilis strain 109GGC020 remarkably inhibited the growth of M. oryzae Triticum in vitro at 20 μg/disk. We tested a number of natural compounds derived from microorganisms and plants and found that five recently discovered linear non-cytotoxic lipopeptides, gageopeptides A–D (1–4) and gageotetrin B (5) from the strain 109GGC020 inhibited the growth of MoT mycelia in a dose-dependent manner. Among the five compounds studied, gageotetrin B (5) displayed the highest mycelial growth inhibition of MoT followed by gageopeptide C (3), gageopeptide D (4), gageopeptide A (1), and gageopeptide B (2) with minimum inhibitory concentrations (MICs) of 1.5, 2.5, 2.5, 10.0, and 10.0 μg/disk, respectively. Application of these natural compounds has also completely blocked formation of conidia in the MoT fungal mycelia in the agar medium. Further bioassay revealed that these compounds (1–5) inhibited the germination of MoT conidia and, if germinated, induced deformation of germ tube and/or abnormal appressoria. Interestingly, application of these linear lipopeptides (1–5) significantly suppressed wheat blast disease on detached wheat leaves. This is the first report of the inhibition of mycelial growth, conidiogenesis, conidial germination, and morphological alterations in the germinated conidia and suppression of wheat blast disease by linear lipopeptides from the strain of B. subtilis. A further study is needed to evaluate the mode of action of these natural compounds for considering them as biopesticides for managing this notorious cereal killer.

The chitosan (CHT) biopolymer is a de-acetylated chitin derivative that exists in the outer shell of shrimp, shellfish, lobster or crabs, as well as fungal cell walls. Because of its biodegradability, environmental non-toxicity, and biocompatibility, it is an ideal resource for sustainable agriculture. The CHT emerged as a promising agent used as a plant growth promoter and also as an antimicrobial agent. It induces plant growth by influencing plant physiological processes like nutrient uptake, cell division, cell elongation, enzymatic activation and synthesis of protein that can eventually lead to increased yield. It also acts as a catalyst to inhibit the growth of plant pathogens, and alter plant defense responses by triggering multiple useful metabolic pathways. This review emphasizes the role and mechanisms of CHT as a plant growth promoter and disease suppressor, and its future implications in agriculture.

Nanotechnology shows high promise in the improvement of agricultural productivity thus aiding future food security. In horticulture, maintaining quality as well as limiting the spoilage of harvested fruit and vegetables is a very challenging task. Various kinds of nanomaterials have shown high potential for increasing productivity, enhancing shelf-life, reducing post-harvest damage and improving the quality of horticultural crops. Antimicrobial nanomaterials as nanofilm on harvested products and/or on packaging materials are suitable for the storage and transportation of vegetables and fruits. Nanomaterials also increase the vitality of the cut flower. Nanofertilizers are target-specific, slow releasing and highly efficient in increasing vegetative growth, pollination and fertility in flowers, resulting in increased yield and improved product quality for fruit trees and vegetables. Formulated nanopesticides are target-specific, eco-friendly and highly efficient. Nanosensors facilitate up-to-date monitoring of growth, plant disease, and pest attack in crop plants under field conditions. These novel sensors are used to precisely identify the soil moisture, humidity, population of crop pests, pesticide residues and figure out nutrient requirements. This review aimed to provide an update on the recent advancement of nanomaterials and their potential uses for enhancing productivity, quality of products, protection from pests and reduction of the postharvest losses of the horticultural crops. This study reveals that nanotechnology could be used to generate cutting-edge techniques towards promoting productivity and quality of horticultural crops to ensure food and nutritional security of ever-increasing population of the world.

Blast diseases, caused by the fungal pathogen Magnaporthe oryzae, are among the most destructive diseases that occur on at least 50 species of grasses, including cultivated cereals wheat, and rice. Although fungicidal control of blast diseases has widely been researched, development of resistance of the pathogen against commercially available products makes this approach unreliable. Novel approaches such as the application of biopesticides against the blast fungus are needed for sustainable management of this economically important disease. Antagonistic microorganisms, such as fungi and probiotic bacteria from diverse taxonomic genera were found to suppress blast fungi both in vitro and in vivo. Various classes of secondary metabolites, such as alkaloids, phenolics, and terpenoids of plant and microbial origin significantly inhibit fungal growth and may also be effective in managing blast diseases. Common modes of action of microbial biocontrol agents include: antibiosis, production of lytic enzymes, induction of systemic resistance in host plant, and competition for nutrients or space. However, the precise mechanism of biocontrol of the blast fungus by antagonistic microorganisms and/or their bioactive secondary metabolites is not well understood. Commercial formulations of biocontrol agents and bioactive natural products could be cost-effective and sustainable but their availability at this time is extremely limited. This review updates our knowledge on the infection pathway of the wheat blast fungus, catalogs naturally occurring biocontrol agents that may be effective against blast diseases, and discusses their role in sustainable management of the disease.

The entomopathogenic fungus Cladosporium cladosporioides is a potential candidate for biocontrol of insect pests. We isolated a strain of C. cladosporioides BOU1 from an infected brown plant hoper (BPH) of rice and characterized it using morpho-physiological and molecular analyses. Internal transcribed spacer regions and intervening 5.8S rRNA gene (ITS) sequencing and morphopathogenic analyses confirmed that BOU1 is a strain of C. cladosporioides. To select the suitable medium for this fungus, a single condium of BOU1 was grown in potato dextrose agar (PDA), potato dextrose agar with yeast (PDAY), Sabouraud dextrose agar (SDA) and synthetic nutrient-poor agar (SNA) media. The suitable medium for this fungal isolate was determined by fungal growth (colony area and conidiogenesis), and enzymatic activities (protease and lipase). The fungal growth parameters including enzymatic activities showed that the PDA medium is most suitable culture medium for C. cladosporioides. Finally, the pathogenicity of this fungal isolate was evaluated against whitefly, Bemisia tabaci through direct contact toxicity assay on eggplant leaves by dipping under laboratory conditions. The BOU1 strain caused mortality in B. tabaci in a dose-dependent manner, the highest mortality being 71% at 1 × 10⁸ conidia/mL. To the best of our knowledge, this is the first report of isolation and molecular characterization of an entomopathogenic fungus C. cladosporioides from a BPH of rice. This study suggests that BOU1 is a potential candidate for biological control of whitefly for the promotion of sustainable agriculture.