Expression analysis on mycoparasitism related genes during antagonism of Trichoderma with Colletotrichum falcatum causing red rot in sugarcane

Half-Century Scientometric Analysis: Unveiling the Excellence of Fungi as Biocontrol Agents and Biofertilisers

Reducing the use of chemical inputs is becoming a major challenge in developing sustainable agriculture. Fungi, known as biocontrol agents (BCAs) and biofertilisers, are crucial in scientific research and are celebrated for their efficacy, eco-friendliness, and multifaceted roles. In this study, a bibliometric analysis was conducted on 5349 articles related to fungi as BCAs and biofertilisers over the past half-century using the Web of Science Core Collection (WoSCC) database. The publications on fungi, such as BCAs and biofertilisers, have increased significantly over the last 20 years, with a maximum growth rate of 33.7%. The USA and China lead in this field. Keyword clustering analysis revealed that entomopathogenic fungi, including Hemiptera, Coleoptera, and Lepidoptera, can be used to manage plant pests. It also showed that fungi can be used as biofertilisers to promote plant growth. The analysis of research trends shows that Beauveria bassiana in biological control is highly significant. This study also showed that entomopathogenic fungi control plant pests by infiltrating the insect cuticles. Trichoderma spp. exert biocontrol effects by producing antibiotics. Arbuscular mycorrhizal fungi can trigger plant defence mechanisms by modulating secondary metabolite synthesis. This study contributes to the current knowledge of fungi as BCAs and biofertilisers and can guide future research.

Secondary metabolites and extracellular proteases contribute to the antagonistic action of indigenous Trichoderma strains against Botrytis cinerea

The aim of this work is to evaluate different molecular strategies deployed by indigenous isolates of Trichoderma in their interaction with the phytopathogen Botrytis cinerea. In vitro antagonism assays, determination of volatile and diffusible compounds, and the relative expression of the prb1 gene, which codes for an extracellular protease, before and during the stage of direct contact between the two fungi, were carried out; the characterization of this protease was also performed. All 17 Trichoderma strains tested showed high levels of inhibition against B. cinerea growth in dual culture, with overgrowth of antagonist colonies on top of pathogen colonies being observed in most cases. Pathogen growth inhibition by antagonist-released volatile compounds ranged from 17 to 100 %, while the inhibition linked to the production of diffusible compounds ranged from 13 to 100 %. The prb1 gene was shown to be three-fold upregulates compared to growth alone before direct contact between the two fungi was established and then its transcript levels declined again at the direct contact stage. In the Trichoderma culture supernatant, the presence of elastase-type serine proteases (SP) associated with the initiation of the mycoparasitism process could be observed.

Native and Non-Native Soil and Endophytic Trichoderma spp. from Semi-Arid Sisal Fields of Brazil Are Potential Biocontrol Agents for Sisal Bole Rot Disease

Sisal (Agave sisalana) bole rot caused by Aspergillus welwitschiae is the main phytosanitary problem affecting sisal in the Brazilian semi-arid region. The aim of this study was to evaluate Trichoderma spp. as biocontrol agents for sisal bole rot. Native and non-native species, both soil inhabitants and endophytes, and isolated from different plant hosts were tested. Anatomical studies of the interaction among A. sisalana, Trichoderma spp., and A. welwitschiae were performed. T. cf. asperellum (isolate F12), an endophyte of sisal leaves; T. cf. asperellum (TCS83) from banana plant soil; T. lentiforme (TCS15) and T. harzianum (species complex) (TCS35 and TCS76) from sisal root soil; T. spirale (R62) and T. saturnisporum (R75), endophytes of sisal roots, were the most efficient isolates, with inhibition of A. welwitschiae mycelial growth by up to 70%, and inhibition of sporulation and spore germination by 99%. A reduction in disease incidence of 70 to 93% and in disease severity of 97% was achieved. T. lentiforme (TCS1), T. harzianum (species complex) (TCS35 and R72), and T. koningiopsis (R78) showed mycoparasitism. An increase in cell wall thickness of bole tissue colonized by these Trichoderma species indicated that induced plant defense responses occurred, preventing pathogen colonization, which should be further investigated. Native and non-native Trichoderma species can control sisal bole rot disease.

Agricultural Pest Management: The Role of Microorganisms in Biopesticides and Soil Bioremediation

Pesticide use in crops is a severe problem in some countries. Each country has its legislation for use, but they differ in the degree of tolerance for these broadly toxic products. Several synthetic pesticides can cause air, soil, and water pollution, contaminating the human food chain and other living beings. In addition, some of them can accumulate in the environment for an indeterminate amount of time. The agriculture sector must guarantee healthy food with sustainable production using environmentally friendly methods. In this context, biological biopesticides from microbes and plants are a growing green solution for this segment. Several pests attack crops worldwide, including weeds, insects, nematodes, and microorganisms such as fungi, bacteria, and viruses, causing diseases and economic losses. The use of bioproducts from microorganisms, such as microbial biopesticides (MBPs) or microorganisms alone, is a practice and is growing due to the intense research in the world. Mainly, bacteria, fungi, and baculoviruses have been used as sources of biomolecules and secondary metabolites for biopesticide use. Different methods, such as direct soil application, spraying techniques with microorganisms, endotherapy, and seed treatment, are used. Adjuvants like surfactants, protective agents, and carriers improve the system in different formulations. In addition, microorganisms are a tool for the bioremediation of pesticides in the environment. This review summarizes these topics, focusing on the biopesticides of microbial origin.

Trichoderma as a biological control agent: mechanisms of action, benefits for crops and development of formulations

Currently, the food and economic losses generated by the attack of phytopathogens on the agricultural sector constitute a severe problem. Conventional crop protection techniques based on the application of synthetic pesticides to combat these undesirable microorganisms have also begun to represent an inconvenience since the excessive use of these substances is associated with contamination problems and severe damage to the health of farmers, consumers, and communities surrounding the fields, as well as the generation of resistance by the phytopathogens to be combated. Using biocontrol agents such as Trichoderma to mitigate the attack of phytopathogens represents an alternative to synthetic pesticides, safe for health and the environment. This work explains the mechanisms of action through which Trichoderma exerts biological control, some of the beneficial aspects that it confers to the development of crops through its symbiotic interaction with plants, and the bioremedial effects that it presents in fields contaminated by synthetic pesticides. Also, detail the production of spore-based biopesticides through fermentation processes and formulation development.

ATP-Binding Cassette (ABC) Transporters in Fusarium Specific Mycoparasite Sphaerodes mycoparasitica during Biotrophic Mycoparasitism

Recent transcriptomic profiling has revealed importance membrane transporters such as ATP-binding cassette (ABC) transporters in fungal necrotrophic mycoparasites. In this study, RNA-Seq allowed rapid detection of ABC transcripts involved in biotrophic mycoparasitism of Sphaerodes mycoparasitica against the phytopathogenic and mycotoxigenic Fusarium graminearum host, the causal agent of Fusarium head blight (FHB). Transcriptomic analyses of highly expressed S. mycoparasitica genes, and their phylogenetic relationships with other eukaryotic fungi, portrayed the ABC transporters’ evolutionary paths towards biotrophic mycoparasitism. Prior to the in silico phylogenetic analyses, transmission electron microscopy (TEM) was used to confirm the formation of appressorium/haustorium infection structures in S. mycoparasitica during early (1.5 d and 3.5 d) stages of mycoparasitism. Transcripts encoding biotrophy-associated secreted proteins did uncover the enrolment of ABC transporter genes in this specific biocontrol mode of action, while tandem ABC and BUB2 (non-ABC) transcripts seemed to be proper for appressorium development. The next-generation HiSeq transcriptomic profiling of the mycoparasitic hypha samples, revealed 81 transcripts annotated to ABC transporters consisting of a variety of ABC-B (14%), ABC-C (22%), and ABC-G (23%), and to ABC-A, ABC-F, aliphatic sulfonates importer (TC 3.A.1.17.2), BtuF, ribose importer (TC 3.A.1.2.1), and unknown families. The most abundant transcripts belonged to the multidrug resistance exporter (TC 3.A.1.201) subfamily of the ABC-B family, the conjugate transporter (TC 3.A.1.208) subfamily of the ABC-C family, and the pleiotropic drug resistance (PDR) (TC 3.A.1.205) subfamily of the ABC-G family. These findings highlight the significance of ABC transporter genes that control cellular detoxification against toxic substances (e.g., chemical pesticides and mycotoxins) in sustaining a virulence of S. mycoparasitica for effective biotrophic mycoparasitism on the F. graminearum host. The findings of this study provide clues to better understand the biotrophic mycoparasitism of S. mycoparasitica interacting with the Fusarium host, which implies that the ABC transporter group of key proteins is involved in the mycoparasite’s virulence and multidrug resistance to toxic substances including cellular detoxification.

Red rot of sugarcane (Colletotrichum falcatumWent)

Red rot of sugarcane was recorded more than 100 years before in Java, India, Argentina, USA and other countries, and it is one of the most devastating diseases of sugarcane. Since the cultivated sugarcane (Saccharum officinarum) has failed across the countries, systematic inter-specific hybridization betweenS. officinarumand the wild speciesS. spontaneumreferred as ‘nobilization’ was done to develop resistant varieties and the disease was managed in most of the countries. However, in the countries especially in Asia, varietal breakdown to red rot caused severe epiphytotics, by which the resistant varieties failed in the field at regular intervals. New pathogenic strains ofColletotrichum falcatumwith higher virulence were found responsible for varietal breakdown in sugarcane. Extensive cultivation of a single variety over large areas led to extensive crop damages due to ‘vertifolia’ effect in different decades in India. The current epiphytotic on the ruling variety Co 0238 has caused loss of more than one billion US dollars in the current season in the country. Detailed studies were done on pathogenic variation, epidemiology, screening methods, disease resistance mechanism, identifying effectors, pathogenicity determinants, antifungal genes and transgenics. Recently, complete genome and transcriptomes ofC. falcatumwere sequenced and pathogenicity hot spots and candidate secreted effector proteins were identified and this will further help to identify the candidate genes for further genetic manipulation. In spite of poor understanding on inheritance of resistance toC. falcatumin sugarcane, new varieties with red rot resistance were developed and deployed after each of the epiphytotic to save the crop. Further, other management practices including bioagents, chemicals and inducers were attempted and improved efficacy by mechanized sett treatment showed promising results to manage the disease under field conditions.