qPCR quantification of Sphaerodes mycoparasitica biotrophic mycoparasite interaction with Fusarium graminearum: in vitro and in planta assays

Insights into Wheat Genotype‒Sphaerodes mycoparasitica Interaction to Improve Crop Yield and Defence against Fusarium graminearum: An Integration of FHB Biocontrol in Canadian Wheat Breeding Programmes

Fusarium head blight (FHB) is a major threat to wheat crop production and food security worldwide. The creation of resistant wheat cultivars is an essential component of an integrated strategy against Fusarium graminearum, the primary aetiological agent that causes FHB. The results of this study show that the deployment of proto-cooperative interactions between wheat genotypes and mycoparasitic biocontrol agents (BCAs) can improve crop yield and plant resistance in controlling the devastating effects of FHB on wheat agronomic traits. A Fusarium-specific mycoparasite, Sphaerodes mycoparasitica, was found to be compatible with common and durum wheat hosts, thus allowing the efficient control of F. graminearum infection in plants. Four genotypes of wheat, two common wheat, and two durum wheat cultivars with varying FHB resistance levels were used in this greenhouse study. The BCA treatments decreased FHB symptoms in all four cultivars and improved the agronomic traits such as spike number, spike weight, seed weight, plant biomass, and plant height which are vital to grain yield. Conversely, the F. graminearum 3ADON chemotype treatment decreased the agronomic trait values by up to 44% across cultivars. Spike number, spike weight, and seed weight were the most improved traits by the BCA. A more measurable improvement in agronomic traits was observed in durum wheat cultivars compared to common wheat.

Update on the state of research to manage Fusarium head blight

Fusarium head blight (FHB) is one of the most devastating diseases of cereal crops, causing severe reduction in yield and quality of grain worldwide. In the United States, the major causal agent of FHB is the mycotoxigenic fungus, Fusarium graminearum. The contamination of grain with mycotoxins, including deoxynivalenol and zearalenone, is a particularly serious concern due to its impact on the health of humans and livestock. For the past few decades, multidisciplinary studies have been conducted on management strategies designed to reduce the losses caused by FHB. However, effective management is still challenging due to the emergence of fungicide-tolerant strains of F. graminearum and the lack of highly resistant wheat and barley cultivars. This review presents multidisciplinary approaches that incorporate advances in genomics, genetic-engineering, new fungicide chemistries, applied biocontrol, and consideration of the disease cycle for management of FHB.

Protocooperative Effect of Sphaerodes mycoparasitica Biocontrol and Crop Genotypes on FHB Mycotoxin Reduction in Bread and Durum Wheat Grains Intended for Human and Animal Consumption

The occurrence of Fusarium Head Blight (FHB) mycotoxins in wheat grains is a major threat to global food safety and security. Humans and animals are continuously being exposed to Fusarium mycotoxins such as deoxynivalenol (DON) and its acetylated derivatives 3ADON and 15ADON through the ingestion of contaminated food or grain-based diet. In this study, a host-specific mycoparasite biocontrol agent (BCA), Sphaerodes mycoparasitica, significantly reduced FHB mycotoxin occurrence in harvested wheat grains from Fusarium graminearum 3ADON chemotype infected plants in greenhouse. Four genotypes of wheat, two common wheat and two durum wheat cultivars with varying FHB resistance levels were used in this study. Principal Coordinate Analysis (PCoA) using Illumina ITS sequences depicted beta diversity changes in Fusarium species indicating that both plant cultivar and BCA treatments influenced the Fusarium species structure and mycotoxin occurrence in grains. Fusarium graminearum complex (cluster A), F. avenaceum and F. acuminatum (cluster B), and F. proliferatum (cluster C) variants were associated with different FHB mycotoxins based on LC-MS/MS analyses. The predominant FHB mycotoxins measured were DON and its acetylated derivatives 3ADON and 15ADON. The BCA reduced the occurrence of DON in grains of all four cultivars (common wheat: 1000-30,000 µg·kg^-1.; durum wheat: 600-1000 µg·kg^-1) to levels below the Limit of Quantification (LOQ) of 16 µg·kg^-1. A relatively higher concentration of DON was detected in the two common wheat genotypes when compared to the durum wheat genotype; however, the percentage reduction in the wheat genotypes was greater, reaching up to 99% with some S. mycoparasitica treatments. Similarly, a higher reduction in DON was measured in susceptible genotypes than in resistant genotypes. This study's findings underscore the potential of a Fusarium-specific S. mycoparasitica BCA as a safe and promising alternative that can be used in conjunction with other management practices to minimize FHB mycotoxins in cereal grain, food and feed intended for human and animal consumption.

The Importance of Microorganisms for Sustainable Agriculture-A Review

In the face of climate change, progressive degradation of the environment, including agricultural land negatively affecting plant growth and development, endangers plant productivity. Seeking efficient and sustainable agricultural techniques to replace agricultural chemicals is one of the most important challenges nowadays. The use of plant growth-promoting microorganisms is among the most promising approaches; however, molecular mechanisms underneath plant-microbe interactions are still poorly understood. In this review, we summarized the knowledge on plant-microbe interactions, highlighting the role of microbial and plant proteins and metabolites in the formation of symbiotic relationships. This review covers rhizosphere and phyllosphere microbiomes, the role of root exudates in plant-microorganism interactions, the functioning of the plant's immune system during the plant-microorganism interactions. We also emphasized the possible role of the stringent response and the evolutionarily conserved mechanism during the established interaction between plants and microorganisms. As a case study, we discussed fungi belonging to the genus Trichoderma. Our review aims to summarize the existing knowledge about plant-microorganism interactions and to highlight molecular pathways that need further investigation.

Plant-Microbe Interaction in Sustainable Agriculture: The Factors That May Influence the Efficacy of PGPM Application

The indiscriminate use of chemical fertilizers and pesticides has caused considerable environmental damage over the years. However, the growing demand for food in the coming years and decades requires the use of increasingly productive and efficient agriculture. Several studies carried out in recent years have shown how the application of plant growth-promoting microbes (PGPMs) can be a valid substitute for chemical industry products and represent a valid eco-friendly alternative. However, because of the complexity of interactions created with the numerous biotic and abiotic factors (i.e., environment, soil, interactions between microorganisms, etc.), the different formulates often show variable effects. In this review, we analyze the main factors that influence the effectiveness of PGPM applications and some of the applications that make them a useful tool for agroecological transition.

Evolution of Fusarium Head Blight Management in Wheat: Scientific Perspectives on Biological Control Agents and Crop Genotypes Protocooperation

Over the past century, the economically devastating Fusarium Head Blight (FHB) disease has persistently ravished small grain cereal crops worldwide. Annually, losses globally are in the billions of United States dollars (USD), with common bread wheat and durum wheat accounting for a major portion of these losses. Since the unforgettable FHB epidemics of the 1990s and early 2000s in North America, different management strategies have been employed to treat this disease. However, even with some of the best practices including chemical fungicides and innovative breeding technological advances that have given rise to a spectrum of moderately resistant cultivars, FHB still remains an obstinate problem in cereal farms globally. This is in part due to several constraints such as the Fusarium complex of species and the struggle to develop and employ methods that can effectively combat more than one pathogenic line or species simultaneously. This review highlights the last 100 years of major FHB epidemics in the US and Canada, as well as the evolution of different management strategies, and recent progress in resistance and cultivar development. It also takes a look at protocooperation between specific biocontrol agents and cereal genotypes as a promising tool for combatting FHB.

Tremellomycetes Yeasts in Kernel Ecological Niche: Early Indicators of Enhanced Competitiveness of Endophytic and Mycoparasitic Symbionts against Wheat Pathobiota

Tremellomycetes rDNA sequences previously detected in wheat kernels by MiSeq were not reliably assigned to a genus or clade. From comparisons of ribosomal internal transcribed spacer region (ITS) and subsequent phylogenetic analyses, the following three basidiomycetous yeasts were resolved and identified: Vishniacozymavictoriae, V. tephrensis, and an undescribed Vishniacozyma rDNA variant. The Vishniacozyma variant’s clade is evolutionarily close to, but phylogenetically distinct from, the V. carnescens clade. These three yeasts were discovered in wheat kernel samples from the Canadian prairies. Variations in relative Vishniacozyma species abundances coincided with altered wheat kernel weight, as well as host resistance to chemibiotrophic Tilletia (Common bunt—CB) and necrotrophic Fusarium (Fusarium head blight—FHB) pathogens. Wheat kernel weight was influenced by the coexistence of Vishniacozyma with endophytic plant growth-promoting and mycoparasitic biocontrol fungi that were acquired by plants. Kernels were coated with beneficial Penicillium endophyte and Sphaerodes mycoparasite, each of which had different influences on the wild yeast population. Its integral role in the kernel microbiome renders Vishniacozyma a measurable indicator of the microbiome–plant interaction. The ability of NGS technology to detect specific endophytic DNA variants and early changes in dynamics among symbionts within the kernel ecological niche enables the prediction of crop disease emergence, suggesting that advanced microbiological testing may be a potentially useful tool for both phytoprotection and more efficient wheat breeding programs.

Bioprospecting of Rhizosphere-Resident Fungi: Their Role and Importance in Sustainable Agriculture

Rhizosphere-resident fungi that are helpful to plants are generally termed as 'plant growth promoting fungi' (PGPF). These fungi are one of the chief sources of the biotic inducers known to give their host plants numerous advantages, and they play a vital role in sustainable agriculture. Today's biggest challenge is to satisfy the rising demand for crop protection and crop yield without harming the natural ecosystem. Nowadays, PGPF has become an eco-friendly way to improve crop yield by enhancing seed germination, shoot and root growth, chlorophyll production, and fruit yield, etc., either directly or indirectly. The mode of action of these PGPF includes the solubilization and mineralization of the essential micro- and macronutrients needed by plants to regulate the balance for various plant processes. PGPF produce defense-related enzymes, defensive/volatile compounds, and phytohormones that control pathogenic microbes' growth, thereby assisting the plants in facing various biotic and abiotic stresses. Therefore, this review presents a holistic view of PGPF as efficient natural biofertilizers to improve crop plants' growth and resistance.

Specific Mycoparasite-Fusarium Graminearum Molecular Signatures in Germinating Seeds Disabled Fusarium Head Blight Pathogen's Infection

Advances in Infrared (IR) spectroscopies have entered a new era of research with applications in phytobiome, plant microbiome and health. Fusarium graminearum 3-ADON is the most aggressive mycotoxigenic chemotype causing Fusarium head blight (FHB) in cereals; while Sphaerodes mycoparasitica is the specific Fusarium mycoparasite with biotrophic lifestyle discovered in cereal seeds and roots. Fourier transform infrared (FTIR) spectroscopy analyses depicted shifts in the spectral peaks related to mycoparasitism mainly within the region of proteins, lipids, also indicating a link between carbohydrates and protein regions, involving potential phenolic compounds. Especially, S. mycoparasitica contributes to significant changes in lipid region 3050–2800 cm⁻¹, while in the protein region, an increasing trend was observed for the peaks 1655–1638 cm⁻¹ (amide I) and 1549–1548 cm⁻¹ (amide II) with changes in indicative protein secondary structures. Besides, the peak extending on the region 1520–1500 cm⁻¹ insinuates a presence of aromatic compounds in presence of mycoparasite on the F. graminearum root sample. Monitoring shift in improved seed germination, fungus-fungus interface through scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM), and FTIR molecular signatures combined with principal component analysis (PCA) proved useful tools to detect an early mycoparasitism as a vital asset of the preventive biocontrol strategy against plant pathogens.

Dieback of Pinus nigra Seedlings Caused by a Strain of Trichoderma viride

Four different fungi (Trichoderma viride, T. harzianum, Phomopsis sp., and Mortierella sp.) were isolated from 6-year-old Pinus nigra plants showing stunting and high incidence of mortality in a reforestation area of the National Park of Abruzzo, Lazio, and Molise (central Italy). Tests conducted on P. nigra revealed the pathogenic behavior of T. viride isolates with 30 to 80% mortality in artificially inoculated 2-year-old seedlings. The pathogenicity of these isolates was also observed in 10-year-old P. nigra trees and on lemon fruit. This result, in agreement with the constant isolation of T. viride from diseased plants, suggests the possible role of this fungus in the decline of P. nigra plants. T. harzianum and two reference isolates of T. viridarium and T. trixiae did not cause any symptoms, while Phomopsis sp. and Mortierella sp. caused limited necroses around the inoculation point in a few seedlings. Their role in the decline of P. nigra seedlings was considered irrelevant. According to phylogenetic analyses, pathogenic isolates of T. viride clustered in a very uniform group containing strains from different geographic origin and hosts, but none previously reported as a biocontrol agent.