INFLUENCE OF EXOMETABOLITES OF DIFFERENT VARIETIES OF CULTURAL PLANTS ON THE GROWTH AND DEVELOPMENT OF PATHOGENIC MICROMYCETES BIPOLARIS SOROKINIANA AND ALTERNARIA ALTERNATA

Objective. To establish the influence of exometabolites of winter wheat plants of Podolianka, Natalka, Skagen, Mulan varieties and oats of Skarb Ukrainy, Svitanok, Tembr varieties on the growth and development of Bipolaris sorokiniana micromycete, as well as the influence of onion of Tkachenkivska, Mavka, Veselka, Liubchyk, Variah, Harmonia varieties on the growth and development of the micromycete Alternaria alternata. Methods. Mycological, phytopathological, phytoimmunological. Results. Two hundred isolates of pathogenic micromycetes were isolated from the seeds of the studied crops of different varieties. The most common microbiota were: Bipolaris sorokiniana, Alternaria alternata, Alternaria tenuissima, Alternaria infectoria, Stemphylium vesicarium, Curvularia inaequalis. The highest incidence on wheat and oat seeds (over 80 %) was reported for B. sorokiniana, on onion seeds — for A. alternata. It was found that exometabolites of plants of different varieties can both inhibit and stimulate the rate of radial growth of mycelium of B. sorokiniana and A. alternata. It was proved that exometabolites of plants of wheat, oats, onion can significantly affect the reproductive capacity of the studied micromycetes, which reduced the number of spores per 1 cm2 of colony area almost 1.2–2.5 times compared to the control. This indicates that exometabolites of plants are characterized by fungicidal properties, which are due to a complex of biologically active substances that can inhibit the intensity of sporulation of B. sorokiniana and A. alternate. Conclusion. The antifungal property of root exometabolites of plants of the studied varieties significantly depends on the genotype of the variety. Therefore, an important timely task is to identify environmentally stable and flexible varieties that are characterized by group resistance to pathogens of fungal origin, as well as the search for mechanisms of action of fungicidal natural origin.

Emerging Cutaneous Phaeohyphomycosis Caused by Alternaria infectoria

Alternaria species belong to a group of opportunistic fungi that causes skin infection mainly in immunosuppressed patients. The authors describe two clinically distinct cases of cutaneous alternariosis caused by Alternaria infectoria in patients under prolonged corticosteroid treatment. Additionally, a brief review of published cases in portuguese patients is conducted.

Stem Endophytic Mycobiota in Wild and Domesticated Wheat: Structural Differences and Hidden Resources for Wheat Improvement

Towards the identification of entophytic fungal taxa with potential for crop improvement, we characterized and compared fungal endophyte communities (FECs) from domesticated bread wheat and two wheat ancestors, Aegilopssharonensis and Triticumdicoccoides. Data generated by next generation sequencing identified a total of 1666 taxa. The FECs in the three plant species contained high proportions of random taxa with low abundance. At plant species level, the majority of abundant taxa were common to all host plants, and the collective FECs of each of the three plant species had similar diversity. However, FECs from the wild plants in specific sites were more diverse and had greater richness than wheat FECs from corresponding specific fields. The wild plants also had higher numbers of differentially abundant fungal taxa than wheat, with Alternaria infectoria being the most abundant species in wild plants and Candida sake the most abundant in wheat. Network analysis on co-occurrence association revealed a small number of taxa with a relatively high number of co-occurrence associations, which might be important in community assembly. Our results show that the actual endophytic cargo in cultivated wheat plants is limited relative to wild plants, and highlight putative functional and hub fungal taxa with potential for wheat improvement.

Pathogenic and Non-Pathogenic Fungal Communities in Wheat Grain as Influenced by Recycled Phosphorus Fertilizers: A Case Study

Waste-based fertilizers provide an alternative to fertilizers made from non-renewable phosphate rock. Fungal communities colonizing the grain of spring wheat fertilized with preparation from sewage sludge ash and dried animal blood (Rec) and the same fertilizer activated by Bacillus megaterium (Bio) were evaluated against those resulting from superphosphate (SP) and no phosphorus (control, C0) treatments. The Illumina MiSeq sequencing system helped to group fungal communities into three clades. Clade 1 (communities from C0, Bio 60 and 80, Rec 80 and SP 40 kg P2O5 ha−1 treatments) was characterized by a high prevalence of Alternaria infectoria, Monographella nivalis and Gibberella tricincta pathogens. Clade 2 (Bio 40 kg, Rec 40 and 60 kg, and SP 60 kg P2O5 ha−1) was characterized by the lowest amount of the identified pathogens. Commercial SP applied at 80 kg P2O5 ha−1 (clade 3) induced the most pronounced changes in the fungal taxa colonizing wheat grain relative to non-fertilized plants. The above was attributed mainly to the lower amount of A. infectoria and higher counts of species of the family Nectriaceae, mostly epiphytic pathogens Fusarium culmorum and Fusarium poae.

ALTERNARIA BLIGHT OF POME CROPS

The research was carried out on the premises of the experimental study farm of Russian State Agrarian University – Moscow Timiryazev Agricultural Academy in Moscow in 2018–2019. Over two years, the authors collected and microscoped samples of affected plants of different families to determine the causative agents of fungal diseases. The identification of the fungi species of the Alternaria genus was carried out by morphological features of conidia and the habitus of sporulation. It was found that the damage of apple and pear trees is caused by two non-specialized fungus species of Alternaria tenuissima and Alternaria infectoria. It was found that 73% of 110 apple varieties and 47.2% of 53 pear varieties studied were affected to varying degrees by the fungi of the Alternaria genus. The paper describes apple varieties that have been damaged by Alternaria. There has been detected a high malware of Alternaria blight on the young seedlings of pome crops. The species of A. tenuissima and A. infectoria pathogens have been determined to affect dicotyledonous weed plants widely distributed in fruit gardens, as well as a number of garden-protective and ornamental crops. Also, their possible role as infection reservoirs and vectors for fruit crops has been established. The authors considered grade vulnerability to Alternaria blight lesion of different pome and stone fruit varieties. The most Alternaria blight-resistant varieties of pome crops have been identified. The authors have stated the relationship between the degree of Alternaria blight progression and factors such as pest damage and the location of plantings. They also describe some differences in the manifestation of Alternaria blight symptoms on apple and pear trees during the initial period of disease progression. As a result of the studies, recommendations are given on the implementation of protective measures aimed at reducing the spread of Alternaria blight of pome crops in fruit gardens.

The antifungal activity of extracts of Osmundea pinnatifida, an edible seaweed, indicates its usage as a safe environmental fungicide or as a food additive preventing post-harvest fungal food contamination

Extracts of the edible seaweed Osmundea pinnatifida impair Aspergillus fumigatus and Alternaria infectoria conidiation.