Adriana Knob

Spot blotch caused by Bipolaris sorokiniana is a major threat to barley production worldwide. Although the genus Trichoderma is widely recognized for its biocontrol potential, the extent to which genetic diversity among distinct pathogen isolates influences antagonistic responses remains poorly understood. This study screened eight native Trichoderma isolates from threatened Araucaria Forest remnants against six B. sorokiniana field isolates using exclusively in vitro assays. Pathogen genetic diversity was assessed using inter-simple sequence repeat (ISSR) markers, while biocontrol potential was evaluated through dual culture and volatile/non-volatile metabolite production. Nei’s genetic diversity ( h = 0.444) and Shannon’s information index ( I = 0.634) revealed high genetic diversity among B. sorokiniana isolates, with no obvious relationship to sampling location. Our results showed that the antagonistic efficacy of Trichoderma varied according to the B. sorokiniana isolate. Although all Trichoderma isolates inhibited pathogen growth, their performance was highly isolate-dependent: the commercial standard T. harzianum exhibited the highest inhibition (up to 94%), followed by the native isolates T. harzianum LMA A14 and T. azevedoi LMA A22 (up to 82%) in dual culture, whereas T. asperelloides (LMA A20 and LMA A24) and T. longibrachiatum LMA A21 excelled differentially in volatile and non-volatile metabolite production, showing distinct suppression profiles across different B. sorokiniana genotypes. This study suggests that microbial biocontrol is a dynamic interaction in which variability among pathogen isolates may influence antagonist performance, highlighting the importance of evaluating a range of them when screening broad-spectrum native biocontrol candidates for sustainable disease management.

The aim of this paper was to evaluate the effect of essential oils from the Lamiaceae family on the control of Colletotrichum gloeosporioides, Elsinoë ampelina and Phytophthora infestans, as well as to investigate mode of action of the most effective essential oils. Capitalize oils of Lavender (LEO), Basil (BEO), Mint (MEO), Oregano (OEO) and Thyme (TEO) were used at doses of 0, 250, 500, 750 and 1000 µL L⁻¹. Effects on mycelial growth and spore germination were evaluated to identify the most potent essential oils. Additionally, the action of volatile compounds and the effects of the oils effect on ergosterol content, membrane permeability, and transfer test assessed. OEO and TEO were the most promising, completely inhibiting the development of phytopathogens at nearly all tested doses. Consequently, these two essential oils were selected for further analysis, except 250 µL L⁻¹dose, which did not completely inhibit the phytopathogens. Regarding ergosterol content, OEO significantly reduced ergosterol levels in C. gloeosporioides and E. ampelina, while TEO decreased only the ergosterol content of C. gloeosporioides, and did not interfere with the other microorganism. The membrane permeability was also affected by the two essential oils. Only OEO showed no effect on the membrane permeability of E. ampelina. The study also revealed that OEO and TEO exhibited fungicidal effects against C. gloeosporioides and E. ampelina, while showing fungistatic effects against P. infestans. In conclusion, OEO and TEO were found to be the most effective oils in the management of C. gloeosporioides, E. ampelina, and P. infestans. Their distinct mechanisms of action further indicate their potential as potent agents for directly controlling plant diseases.

The diversity of endophytes and their ecological relationships with the endangered conifer Araucaria angustifolia (a critically endangered species) are unrevealed. This study aimed to characterize the diversity of endophytic fungi associated with A. angustifolia. To this end, we analyzed 90 fragments from five individuals collected from a mixed localized fragment in Guarapuava-PR, Brazil. The total DNA of 61 morphotypes was extracted and the Internal Transcribed Spacer (ITS) region was amplified and sequenced. The sequence analysis allowed the identification of 37 genera belonging to the phylum Ascomycota and the classes Eurotiomycetes, Dothideomycetes, and Sordariomycetes, divided into 11 orders and 13 families. Most of the isolated fungi belonged to the Sordariomycetes class (40%) and to the Xylaria genus (14%), while Eurotiomycetes was the minority class within the community. Our results reveal the high endophytic richness supporting the life cycle of A. angustifolia and reinforce the necessity for the conservation of this conifer, as many genetic resources can be lost owing to its irrational exploration.

High-quality seedlings are one of the key factors in achieving high yield and precocity of blueberries. The inoculation of arbuscular mycorrhizal fungi (AMF) can enhance the development of seedlings in the nursery, ensuring more vigorous seedlings in a shorter time. This study evaluated the effect of inoculation of arbuscular mycorrhizal fungi on the development of ‘PowderBlue’blueberryseedlings. The treatments were arranged in a 4 x 2 factorial scheme, in which the first factor was the arbuscular mycorrhizal fungi Gigaspora rosea, Glomus clarum, G. rosea + G. clarum, and a control level without mycorrhizae, while the second factor consisted of usingindole-3-butyric acid(IBA) and a control level without IBA. Semi-hardwood cuttings were planted in pots containing sterilized soil and kept in a greenhouse for 660 days. The percentage of rooted cuttings, plant height, root system length, shoot dry mass, root dry mass, total dry mass, peroxidase (POD) and superoxide dismutase (SOD) enzyme activities, SPAD index, mycorrhizal efficiency and dependence, number of spores, and soil basal respiration were evaluated. Plants inoculated with G. clarum without IBA and inoculated with G. rosea with IBA showed higher dry matter and SOD and POD enzyme activities, but the use of IBA had a negative effect on the fungus. The inoculation of blueberry cuttings with G. clarummay help seedlingdevelopment, thus improving biometric and biochemical parameters. Furthermore, the plant regulator IBAwas essential in establishing the symbiosis between blueberry and the AMF G. rosea.

No-tillage system (NTS) plays a prominent role in conservation agriculture, however, its benefits can be further improved by adopting complementary soil management and conservation practices, such as using autumnal cover crops, contour seeding, and terraces. This study aimed to evaluate how soil biological activity responds to soil management and conservation systems. The treatments consisted of three macroplots with an area of 11.000 m ² each, as follows: a) Non-Terraced catchment (NTC), cultivated in NTS similar to most farmers of the region, in which the agricultural operations are carried out in the direction of the slope and without terraces used; b) Best Management Practices (BMPs) were adopted in NTS with additional autumnal cultivation of cover crops, and also the direction of machine traffic was transverse to the slope direction; and c) Terraced catchment (TC), cultivated in NTS was associated to mechanical practices to erosion control, using wide base terrace on level. Soil microbial properties sampled in the 0.00-0.10 m layer were evaluated during 2019, 2020, and 2021, all shortly after the summer crop harvest. Natural inoculum potential of arbuscular mycorrhizal fungi (AMF), respirometry, metabolic coefficient, acid phosphatase activity, and organic carbon and nitrogen in the microbial biomass were assessed. Averages of each microbiological properties were compared through the confidence intervals (p2 compared to BMPs and TC, respectively. The BMPs and TC were able to retain 13.8 and 16.5 % more carbon in the microbial biomass and 8.0 and 8.8 % more nitrogen in the biomass than NTC, respectively. Adopting soil management and conservation practices such as autumn cover crops, level seeding, and wide base terrace on level improved the soil microbial properties, with an increase in AMF inoculum potential, higher levels of acid phosphatase activity, and increment of carbon and nitrogen in microbial biomass.

L-Asparaginase (l-ASNase) is a potent chemotherapeutic drug employed to treat leukemia and lymphoma. Currently, l-ASNases for therapeutic use are obtained from Escherichia coli and Dickeya chrysanthemi (Erwinia chrysanthemi). Despite their therapeutic potential, enzymes from bacteria are subject to inducing immune responses, resulting in a higher number of side effects. Eukaryote producers, such as fungi, may provide therapeutic alternatives through enzymes that induce relatively less toxicity and immune responses. Additional expected benefits from yeast-derived enzymes include higher activity and stability in physiological conditions. This work describes the new potential therapeutic candidate l-ASNase from the yeast Meyerozyma guilliermondii. A statistical approach (full factorial central composite design) was used to optimize l-ASNase production, considering l-asparagine and glucose concentration, pH of the medium, and cultivation time as independent factors. In addition, the crude enzymes were biochemically characterized, in terms of temperature and optimal pH, thermostability, pH stability, and associated glutaminase or urease activities. Our results showed that enzyme production increased after supplementing a pH 4.0 medium with 1.0% l-asparagine and 0.5% glucose during 75 h of cultivation. Under these optimized conditions, l-ASNase production reached 26.01 U mL⁻¹, which is suitable for scale-up studies. The produced l-ASNase exhibits maximal activity at 37 °C and pH 7.0 and is highly stable under physiological conditions. In addition, M. guilliermondii l-ASNase has no associated glutaminase or urease activities, demonstrating its potential as a promising antineoplastic agent.

Thermophilic fungi constitute an ecologically well-defined group, commonly found in environments wherever decomposition of organic matter takes place, making them self-heating. The importance of thermophilic fungus in ecosystems contrasts with the incompleteness of our understanding of the group's biogeography patterns, phylogenies and coevolution relationships. Actually, the lack of data about thermophilic fungi from the Brazil is a limiting factor that also contributes for this scenario. In order to reduce this gap of knowledge, we aimed to characterize thermophilic filamentous fungi in Araucaria Forest, Atlantic Forest biome. Species identification was achieved by using internal transcribed spacers (ITS) as molecular ribosomal markers. In total, 240 heat-tolerant fungal strains were isolated and identified as Thermothielavioides terrestris, Thielavia sp., Thermoascus crustaceus, Aspergillus fumigatus, Rhizomucor miehei, Rhizomucor pusillus, and Rhizopus microsporus. All thermophilic strains exhibited optimal growth at 45 °C. T. crustaceus, T. miehei e R. pusillus were the dominant species, with the frequencies of occurrence of 35.00%, 28.33% and 23.33%, respectively. Our data reveals the apparent diversity of the Neotropical realm and may serve as reference to future studies that will try to elucidate important aspects of group.