Plant growth-promoting traits of yeasts isolated from Spanish vineyards: benefits for seedling development

Exploring the potential of Meyerozyma caribbica and its combined application with bacteria for lindane bioremediation

This study explored the degradation potential of a yeast strain, Meyerozyma caribbica, alone and in combination with Bacillus velezensis and Priestia megaterium, found novel for lindane biodegradation. Isolated from hexachlorocyclohexane (HCH)-contaminated sites, M. caribbica, B. velezensis, and P. megaterium demonstrated lindane reduction efficiencies of 86.5%, 78.6%, and 77.5%, respectively, at 750 mg L⁻1 within 10-day incubation period. Kinetic analysis revealed that M. caribbica followed the first-order degradation (r2 = 0.991; T₁/₂ = 4.3 days). Notably, M. caribbica exhibited the highest dechlorinase activity (9.27 U mL⁻1) in the cell supernatant. Co-cultivation as the mixed culture of M. caribbica and P. megaterium achieved maximum lindane reduction (90%) and dechlorinase activity (9.93 U mL⁻1). Whereas the mixed culture of M. caribbica and B. velezensis resulted in 80.9% reduction at 500 mg L⁻1 lindane with dechlorinase activity of 6.77 U mL⁻1. Growth kinetics, modelled using the Monod equation, showed a maximum specific growth rate of 0.416 h⁻1 for the mixed culture of M. caribbica and P. megaterium at 750 mg L⁻1 lindane. GC-MS analysis confirmed the presence of intermediate metabolites, viz., γ-pentachlorocyclohexane, 1,2,4-trichlorobenzene, 1,4-dichlorobenzene and maleyl acetate, validated successive dechlorination and oxidative-reduction processes during lindane biodegradation. The findings of the study highlighted the potential of these novel microbial strains and their mixed cultures for effective bioremediation of lindane-contamination.

Antagonistic Activities of Metschnikowia pulcherrima Isolates Against Penicillium expansum on Amasya Apples

Postharvest fungal diseases cause serious fruit losses and food safety issues worldwide. The trend in preventing food loss and waste has shifted to environmentally friendly and sustainable methods, such as biological control. Penicillium expansum is a common postharvest contaminant fungus that causes blue mould disease and patulin formation on apples. This study aimed to provide biocontrol using Metschnikowia pulcherrima isolates against P. expansum, and to understand their antagonistic action mechanisms. In vitro, 38.77-51.69% of mycelial growth inhibition of P. expansum was achieved by M. pulcherrima isolates with the dual culture assay, while this rate was 69.45-84.89% in the disc diffusion assay. The disease symptoms of P. expansum on wounds were reduced by M. pulcherrima, on Amasya apples. The lesion diameter, 41.84 mm after 12 d of incubation in control, was measured as 24.14 mm when treated with the most effective M. pulcherrima DN-MP in vivo. Although the antagonistic mechanisms of M. pulcherrima isolates were similar, there was a difference between their activities. In general, DN-HS and DN-MP isolates were found to be more effective. In light of all these results, it can be said that M. pulcherrima isolates used in the study have an antagonistic effect against the growth of P. expansum both in vitro and in vivo in Amasya apples, therefore, when the appropriate formulation is provided, they can be used as an alternative biocontrol agent to chemical fungicides in the prevention of postharvest diseases.

Multifarious plant growth-promoting traits of mangrove yeasts: growth enhancement in mangrove seedlings (Rhizophora mucronata) for conservation

Plant Growth-Promoting Yeasts (PGPY) have garnered significant attention in recent years; however, research on PGPY from mangroves remains a largely unexplored frontier. This study, therefore, focused on exploring the multifaceted plant growth-promoting (PGP) capabilities of yeasts isolated from mangroves of Puthuvype and Kumbalam. The present work found that manglicolous yeasts exhibited diverse hydrolytic properties, with the predominance of lipolytic activity, in addition to other traits such as phosphate solubilization, and production of indole acetic acid, siderophore, ammonia, catalase, nitrate, and hydrogen cyanide. After screening for 15 PGP traits, three strains P 9, PV 23, and KV 35 were selected as the most potent ones. These strains also exhibited antagonistic activity against fungal phytopathogens and demonstrated resilience to abiotic stresses, making them not only promising biocontrol agents but also suited for field application. The potent strains P 9, PV 23, and KV 35 were molecularly identified as Candida tropicalis, Debaryomyces hansenii, and Aureobasidium melanogenum, respectively. The potential of these strains in enhancing the growth performance of mangrove seedlings of Rhizophora mucronata, was demonstrated using the pot-experiment. The results suggested that the consortium of three potent strains (P 9, PV 23, and KV 35) was more effective in increasing the number of shoot branches (89.2%), plant weight (87.5%), root length (83.3%), shoot height (57.9%) and total leaf area (35.1%) than the control seedlings. The findings of this study underscore the significant potential of manglicolous yeasts in contributing to mangrove conservation and restoration efforts, offering a comprehensive understanding of their diverse plant growth-promoting mechanisms and highlighting their valuable role in sustainable ecosystem management.

Unlocking the plant growth-promoting potential of yeast spp.: exploring species from the Moroccan extremophilic environment for enhanced plant growth and sustainable farming

In this study, we successfully isolated two distinct yeasts from Moroccan extreme environments. These yeasts were subjected to molecular characterization by analyzing their Internal Transcribed spacer (ITS) regions. Our research thoroughly characterizes plant growth-promoting abilities and their drought and salt stress tolerance. In a greenhouse assay, we examined the impact of selected yeasts on Medicago sativa's growth. Four treatments were employed: (i) control without inoculation (NI), (ii) inoculation with L1, (iii) inoculation with L2, and (iv) inoculation with the mixture L1 + L2. L1 isolated from Toubkal Mountain shared 99.83% sequence similarity to Rhodotorula mucilaginosa. Meanwhile, L2, thriving in the arid Merzouga desert, displayed a similar identity to Naganishia albida (99.84%). Yeast strains were tolerant to NaCl (2 M) and 60% PEG (polyethylene glycol P6000) in case of drought. Both strains could solubilize phsphorus, with L2 additionally demonstrating potassium solubilization. In addition, both strains produce indole acetic acid (up to 135 µl ml-1), have siderophore ability, and produce aminocyclopropane-1-carboxylic acid deaminase. Isolates L1 and L2, and their consortium showed that the single or combined strain inoculation of M. sativa improved plant growth, development, and nutrient assimilation. These findings pave the way for harnessing yeast-based solutions in agricultural practices, contributing to enhanced crop productivity and environmental sustainability.

Assessment of soil yeasts Papiliotrema laurentii S-08 and Saitozyma podzolica S-77 for plant growth promotion and biocontrol of Fusarium wilt of brinjal

AIM

This study aimed to determine the efficacy of the soil yeasts Papiliotrema laurentii S-08 and Saitozyma podzolica S-77 for plant growth promotion (PGP) and biocontrol of wilt disease in brinjal plants while applying yeasts individually or as a consortium in pot experiments.

METHODS AND RESULTS

The yeasts were tested for various PGP characteristics and antagonistic activity against the phytopathogen Fusarium oxysporum f. sp. melongenae. Both the yeast isolates demonstrated some PGP attributes as well as inhibited the growth of the phytopathogen. A gas chromatography-mass spectrometry analysis of the yeast metabolites revealed the presence of several antifungal compounds. The pot experiment performed under nursery conditions showed that applying these yeasts, individually or in consortium, decreased the percent disease incidence in brinjal seedlings while significantly enhancing their growth parameters.

CONCLUSION

Papiliotrema laurentii S-08 and S. podzolica S-77 can be used in brinjal plants as plant growth promoters and also as biocontrol agents against the brinjal wilt disease.

Biochemical and Biotechnological Insights into Fungus-Plant Interactions for Enhanced Sustainable Agricultural and Industrial Processes

The literature is full of studies reporting environmental and health issues related to using traditional pesticides in food production and storage. Fortunately, alternatives have arisen in the last few decades, showing that organic agriculture is possible and economically feasible. And in this scenario, fungi may be helpful. In the natural environment, when associated with plants, these microorganisms offer plant-growth-promoting molecules, facilitate plant nutrient uptake, and antagonize phytopathogens. It is true that fungi can also be phytopathogenic, but even they can benefit agriculture in some way-since pathogenicity is species-specific, these fungi are shown to be useful against weeds (as bioherbicides). Finally, plant-associated yeasts and molds are natural biofactories, and the metabolites they produce while dwelling in leaves, flowers, roots, or the rhizosphere have the potential to be employed in different industrial activities. By addressing all these subjects, this manuscript comprehensively reviews the biotechnological uses of plant-associated fungi and, in addition, aims to sensitize academics, researchers, and investors to new alternatives for healthier and more environmentally friendly production processes.

Plant-beneficial Streptomyces dioscori SF1 potential biocontrol and plant growth promotion in saline soil within the arid and semi-arid areas

Environmental challenges like salinity, drought, fungal phytopathogens, and pesticides directly or/and indirectly influence the environment and agricultural yields. Certain beneficial endophytic Streptomyces sp. can ameliorate environmental stresses and be utilized as crop growth promoters under adverse conditions. Herein, Streptomyces dioscori SF1 (SF1) isolated from seeds of Glycyrrhiza uralensis tolerated fungal phytopathogens and abiotic stresses (drought, salt, and acid base). Strain SF1 showed multifarious plant growth promotion characteristics, including the production of indole acetic acid (IAA), ammonia, siderophores, ACC deaminase, extracellular enzymes, the ability of potassium solubilization, and nitrogen fixation. The dual plate assay showed that strain SF1 inhibited 63.21 ± 1.53%, 64.84 ± 1.35%, and 74.19 ± 2.88% of Rhizoctonia solani, Fusarium acuminatum, and Sclerotinia sclerotiorum, respectively. The detached root assays showed that strain SF1 significantly reduced the number of rotten sliced roots, and the biological control effect on sliced roots of Angelica sinensis, Astragalus membranaceus, and Codonopsis pilosula was 93.33%, 86.67%, and 73.33%, respectively. Furthermore, the strain SF1 significantly increased the growth parameters and biochemical indicators of adversity in G. uralensis seedlings under drought and/or salt conditions, including radicle length and diameter, hypocotyl length and diameter, dry weight, seedling vigor index, antioxidant enzyme activity, and non-enzymatic antioxidant content. In conclusion, the strain SF1 can be used to develop environmental protection biological control agents, improve the anti-disease activity of plants, and promote plant growth in salinity soil within arid and semi-arid regions.

Mycobiota of Mexican Maize Landraces with Auxin-Producing Yeasts That Improve Plant Growth and Root Development

Compared to agrochemicals, bioinoculants based on plant microbiomes are a sustainable option for increasing crop yields and soil fertility. From the Mexican maize landrace "Raza cónico" (red and blue varieties), we identified yeasts and evaluated in vitro their ability to promote plant growth. Auxin production was detected from yeast isolates and confirmed using Arabidopsis thaliana plants. Inoculation tests were performed on maize, and morphological parameters were measured. Eighty-seven yeast strains were obtained (50 from blue corn and 37 from red corn). These were associated with three families of Ascomycota (Dothideaceae, Debaryomycetaceae, and Metschnikowiaceae) and five families of Basidiomycota (Sporidiobolaceae, Filobasidiaceae, Piskurozymaceae, Tremellaceae, and Rhynchogastremataceae), and, in turn, distributed in 10 genera (Clavispora, Rhodotorula, Papiliotrema, Candida, Suhomyces, Soliccocozyma, Saitozyma Holtermaniella, Naganishia, and Aeurobasidium). We identified strains that solubilized phosphate and produced siderophores, proteases, pectinases, and cellulases but did not produce amylases. Solicoccozyma sp. RY31, C. lusitaniae Y11, R. glutinis Y23, and Naganishia sp. Y52 produced auxins from L-Trp (11.9-52 µg/mL) and root exudates (1.3-22.5 µg/mL). Furthermore, they stimulated the root development of A. thaliana. Inoculation of auxin-producing yeasts caused a 1.5-fold increase in maize plant height, fresh weight, and root length compared to uninoculated controls. Overall, maize landraces harbor plant growth-promoting yeasts and have the potential for use as agricultural biofertilizers.

Holistic understanding of the response of grapevines to foliar application of seaweed extracts

Viticulture is highly dependent on phytochemicals to maintain good vineyard health. However, to reduce their accumulation in the environment, green regulations are driving the development of eco-friendly strategies. In this respect, seaweeds have proven to be one of the marine resources with the highest potential as plant protective agents, representing an environmentally-friendly alternative approach for sustainable wine production. The current work follows an interdisciplinary framework to evaluate the capacity of Ulva ohnoi and Rugulopteryx okamurae seaweeds to induce defense mechanisms in grapevine plants. To our knowledge, this is the first study to evaluate Rugulopteryx okamurae as a biostimulator . This macroalgae is relevant since it is an invasive species on the Atlantic and Mediterranean coast causing incalculable economic and environmental burdens. Four extracts (UL1, UL2, RU1 and RU2 developed from Ulva and Rugulopteryx, respectively) were foliar applied to Tempranillo plants cultivated under greenhouse conditions. UL1 and RU2 stood out for their capacity to induce defense genes, such as a PR10, PAL, STS48 and GST1, mainly 24 hours after the first application. The increased expression level of these genes agreed with i) an increase in trans-piceid and trans-resveratrol content, mainly in the RU2 treated leaves, and, ii) an increase in jasmonic acid and decrease in salicylic acid. Moreover, an induction of the activity of the antioxidant enzymes was observed at the end of the experiment, with an increase in superoxide dismutase and catalase in the RU2-treated leaves in particular. Interestingly, while foliar fungal diversity was not influenced by the treatments, alga extract amendment modified fungal composition, RU2 application enriching the content of various groups known for their biocontrol activity. Overall, the results evidenced the capacity of Rugulopteryx okamurae for grapevine biostimulation, inducing the activation of several secondary metabolite pathways and promoting the abundance of beneficial microbiota involved in grapevine protection. While further studies are needed to unravel the bioactive compound(s) involved, including conducting field experiments etc., the current findings are the first steps towards the inclusion of Rugulopteryx okamurae in a circular scheme that would reduce its accumulation on the coast and benefit the viticulture sector at the same time.

Phosphate solubilization and indole acetic acid production by rhizosphere yeast Torulaspora globosa: improvement of culture conditions for better performance in vitro

The rhizosphere yeast Torulaspora globosa is known to produce indole acetic acid (IAA) and to solubilize minerals. Due to the prospective use of this yeast as a biostimulant for agricultural applications, this work aimed to optimize the cultural conditions for both IAA production and phosphate solubilization. For phosphate solubilization, the temperature (20, 25 and 30 °C), initial medium pH (3.0, 5.0, and 7.0), and shaker speed (without mixing, 100 rpm, 150 rpm, and 200 rpm) were considered using the one-factor-at-a-time (OFAT) design. Temperature of 25 °C, initial medium pH 7.0, and static cultures were the conditions of greatest phosphate solubilization, with 40% of the total phosphorus content solubilized from calcium phosphate (419.86 mg L-1) after 48 h. By using the response surface methodology, the maximum IAA production (217.73 µg mL-1) was obtained with the highest initial pH 7.0, the lowest nitrogen, and glucose concentrations (5 g L-1 and 10 g L-1, respectively) and the lowest agitator speed (100 rpm). Further tests indicated that nitrogen affected significantly IAA production and the absence of nitrogen in the medium promoted higher IAA production (457 µg mL-1). The results obtained here may contribute to the scaling up for industrial and agricultural applications of a yeast-based product with T. globosa.

Biostimulation of Plectranthus amboinicus (Lour.) Spreng. with Different Yeast Strains: Morphological Performance, Productivity, Phenotypic Plasticity, and Antioxidant Activity

Due to the growing knowledge about the microorganism–plant relationship, medicinal plants have gained great attention in their bio fertilization programs using biostimulants based on microorganisms. Plectranthus amboinicus (Lour.) Spreng. is a perennial herb belonging to the family Lamiaceae and has therapeutic and nutritional properties attributed to its natural phytochemical compounds, which are highly valued in the pharmaceutical industry. A pot experiment was conducted to evaluate the efficiency of Rhodotorula muciligenese (Y1), Candida sake (Y2), Candida apicola (Y3), and Candida kunwiensis (Y4) yeast strains in concentrations of 0 (C1), 1 × 104 (C2), 1 × 107 (C3), and 1 × 109 (C4) CFU mL−1 on the growth performance, productivity, and antioxidant activity of P. amboinicus plants. Yeast applications promoted growth attributes, nutritional value, and antioxidant activity in P. amboinicus leaves. Candida apicola exhibited the greatest root growth, herb weight, and essential oil production; it also stimulated carbohydrates, protein, and mineral content, as well as DPPH and FRAP activities. Whereas Rhodotorula muciligenese recorded the lowest values in this respect, among the concentrations used, the 1 × 107 CFU mL−1 concentration showed the highest values in this respect. These new findings showed that the foliar application of Candida apicola not only maximized the growth and productivity but also maximized the nutritional value and antioxidant activity of P. amboinicus.

Diversity of Endophytic Yeasts from Agricultural Fruits Positive for Phytohormone IAA Production

This study reports the diversity of cultivable endophytic yeasts from agricultural fruits that respond positively to the plant-promoting property of indole-3-acetic acid (IAA) production. The IAA synthesis by the strains was quantified with an Agilent 1100 series liquid chromatography system. IAA was present in the culture liquid of 72% of all 97 strains examined after three days of cultivation. The most active endophytic yeast strains in this study belonged to the species Aureobasidium pullulans, Candida zeylanoides, Hanseniaspora uvarum, Metschnikowia pulcherrima, Meyerozyma caribbica, Rhodotorula mucilaginosa, and Yarrowia galli. The highest IAA production was observed in the endophytic strain of A. pullulans (9109.19 ± 146.02 μg/g). No significant differences were found between IAA production in strains from agricultural products of different countries. However, the level of IAA production was strictly strain-specific. Our results suggest that the internal tissues of fruits may be a promising source for the isolation of plant-beneficial yeasts that can be used to promote plant growth.

Exploring biotechnological and functional characteristics of probiotic yeasts: A review

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In this review, the probiotic attributes of yeasts other than Saccharomyces boulardii and the various applications of probiotic yeast in biotechnology have been explored.

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This review comprises of the probiotic attributes, antagonistic activity against pathogens, plant growth promoting attributes, industrial application and their biotherapeutic potentials.

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Advanced and additional studies on non-Saccharomyces yeasts are necessary prior to administer these yeasts as potential probiotics for health and wellbeing.

Probiotics are vital and beneficial organisms which offers the health benefits to the host organisms. The fungal probiotic field is one of the developing fields nowadays. Yeast has an enormous and diverse group of microorganisms that is attracting and expanding the attention from researchers and industries. Saccharomyces boulardii, the only patented strain belonging to yeast genera for the human use, has been broadly evaluated for its probiotic effect. Yeasts belonging to the genera Debaryomyces, Pichia, Yarrowia, Meyerozyma, Kluyveromyces etc.., have attained more interest because of their beneficial and probable probiotic features. These yeast probiotics produce VOCs (Volatile organic compounds), mycocins and antimicrobials which shows the antagonistic effect against pathogenic fungi and bacteria. Additionally, those yeasts have been recorded as good plant growth promoting microorganisms. Yeast has an important role in environmental applications such as bioremediation and removal of metals like chromium, mercury, lead etc., from waste water. Probiotic yeasts with their promising antimicrobial, antioxidant, anticancer properties, cholesterol assimilation and immunomodulatory effects can also be utilized as biotherapeutics. In this review article we have made an attempt to address important yeast probiotic attributes.

Culturable Yeast Diversity of Grape Berries from Vitis vinifera ssp. sylvestris (Gmelin) Hegi

Vitis vinifera L. ssp. sylvestris (Gmelin) Hegi is recognized as the dioecious parental generation of today’s cultivars. Climatic change and the arrival of pathogens and pests in Europe led it to be included on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species in 1997. The present work focused on the study of culturable yeast occurrence and diversity of grape berries collected from wild vines. Sampling was performed in 29 locations of Azerbaijan, Georgia, Italy, Romania, and Spain. In total, 3431 yeast colonies were isolated and identified as belonging to 49 species, including Saccharomyces cerevisiae, by 26S rDNA D1/D2 domains and ITS region sequencing. Isolates of S. cerevisiae were also analyzed by SSR–PCR obtaining 185 different genotypes. Classical ecology indices were used to obtain the richness (S), the biodiversity (H’), and the dominance (D) of the species studied. This study highlights the biodiversity potential of natural environments that still represent a fascinating source of solutions to common problems in winemaking.

Seed-Borne Probiotic Yeasts Foster Plant Growth and Elicit Health Protection in Black Gram (Vigna mungo L.)

Black gram is one of the most indispensable components of the world food basket and the growth and health of the crop get influenced by biotic and abiotic factors. Beneficial phyto-microbes are one among them that influence the crop growth, more particularly the seed borne microbes are comparatively beneficial, that they pass from generation to generation and are associated with the plants from establishment to development. In the present study, twenty seed-borne yeasts were characterized and tested for growth promotion of black gram and their antagonism against black gram phytopathogens. Two yeasts, Pichia kudriavzevii POY5 and Issatchenkia terricola GRY4, produced indole acetic acid (IAA), siderophore, 1-amino cyclopropane-1-carboxylic acid deaminase (ACCD), and plant defense enzymes. They solubilized phosphate and zinc and fixed atmospheric nitrogen. Inoculation of these two yeast isolates and Rhizobium BMBS1 improved the seed germination, physiological parameters and yield of black gram. Inoculation of Rhizoctonia solani-challenged plants with plant growth-promoting yeasts, resulted in the synthesis of defense-related enzymes such as peroxidases (POD), chitinases, catalase (CAT), and polyphenol oxidases (PPO). Thus, the seed-borne yeasts, Pichia kudriavzevii POY5 and Issatchenkia terricola GRY4, could be used as plant probiotics for black gram.

Microbial and chemical dynamics of brewers' spent grain during a low-input pre-vermicomposting treatment

The eco-sustainability of industrial processes relies on the proper exploitation of by-products and wastes. Recently, brewers' spent grain (BSG), the main by-product of brewing, was successfully recycled through vermicomposting to produce an organic soil conditioner. However, the pre-processing step there applied (oven-drying) resulted in high costs and the suppression of microbial species beneficial for soil fertility. To overcome these limitations, a low-input pre-processing step was here applied to better exploit BSG microbiota and to make BSG suitable for vermicomposting. During 51 days of pre-treatment, the bacterial and fungal communities of BSG were monitored by denaturing gradient gel electrophoresis (DGGE). Chemical (carbon, nitrogen, ammonium, nitrate content, dissolved organic carbon) and biochemical (dehydrogenase activity) parameters were also evaluated. Mature vermicompost obtained from pre-processed BSG was characterized considering its legal requirements (e.g., absence of pathogens and mycotoxins, lack of phytotoxicity on seeds), microbiota composition, and chemical properties. Results obtained showed that throughout the pre-process, the BSG microbiota was enriched in bacterial and fungal species of significant biotechnological and agronomic potential, including lactic acid bacteria (Weissella, Pediococcus), plant growth-promoting bacteria (Bacillus, Pseudomonas, Pseudoxhantomonas), and biostimulant yeasts (Pichia fermentans, Trichoderma reesei, Beauveria bassiana). Pre-processing increased the suitability of BSG for earthworms' activity to produce high-quality mature vermicompost.

An Updated Global Species Diversity and Phylogeny in the Genus Wickerhamomyces with Addition of Two New Species from Thailand

Ascomycetous yeast species in the genus Wickerhamomyces (Saccharomycetales, Wickerhamomycetaceae) are isolated from various habitats and distributed throughout the world. Prior to this study, 35 species had been validly published and accepted into this genus. Beneficially, Wickerhamomyces species have been used in a number of biotechnologically applications of environment, food, beverage industries, biofuel, medicine and agriculture. However, in some studies, Wickerhamomyces species have been identified as an opportunistic human pathogen. Through an overview of diversity, taxonomy and recently published literature, we have updated a brief review of Wickerhamomyces. Moreover, two new Wickerhamomyces species were isolated from the soil samples of Assam tea (Camellia sinensis var. assamica) that were collected from plantations in northern Thailand. Herein, we have identified these species as W. lannaensis and W. nanensis. The identification of these species was based on phenotypic (morphological, biochemical and physiological characteristics) and molecular analyses. Phylogenetic analyses of a combination of the internal transcribed spacer (ITS) region and the D1/D2 domains of the large subunit (LSU) of ribosomal DNA genes support that W. lannaensis and W. nanensis are distinct from other species within the genus Wickerhamomyces. A full description, illustrations and a phylogenetic tree showing the position of both new species have been provided. Accordingly, a new combination species, W. myanmarensis has been proposed based on the phylogenetic results. A new key for species identification is provided.

Culturable Yeasts as Biofertilizers and Biopesticides for a Sustainable Agriculture: A Comprehensive Review

The extensive use of synthetic fertilizers and pesticides has negative consequences in terms of soil microbial biodiversity and environmental contamination. Faced with this growing concern, a proposed alternative agricultural method is the use of microorganisms as biofertilizers. Many works have been focused on bacteria, but the limited literature on yeasts and their potential ability to safely promote plant growth is gaining particular attention in recent years. Thus, the objective of this review is to highlight the application of yeasts as biological agents in different sectors of sustainable agricultural practices through direct or indirect mechanisms of action. Direct mechanisms include the ability of yeasts to provide soluble nutrients to plants, produce organic acids and phytohormones (indole-3-acetic acid). Indirect mechanisms involve the ability for yeasts to act as biocontrol agents through their high antifungal activity and lower insecticidal and herbicidal activity, and as soil bioremediating agents. They also act as protective agents against extreme environmental factors by activating defense mechanisms. It is evident that all the aspects that yeasts offer could be useful in the creation of quality biofertilizers and biopesticides. Hence, extensive research on yeasts could be promising and potentially provide an environmentally friendly solution to the increased crop production that will be required with a growing population.

Exploring the Potential of Meyerozyma guilliermondii on Physiological Performances and Defense Response against Fusarium Crown Rot on Durum Wheat

Coating seeds with bio-control agents is a potentially effective approach to reduce the usage of pesticides and fertilizers applied and protect the natural environment. This study evaluated the effect of seed coating with Meyerozyma guilliermondii, strain INAT (MT731365), on seed germination, plant growth and photosynthesis, and plant resistance against Fusarium culmorum, in durum wheat under controlled conditions. Compared to control plants, seed coating with M. guilliermondii promoted the wheat growth (shoot and roots length and biomass), and photosynthesis and transpiration traits (chlorophyll, ɸPSII, rates of photosynthesis and transpiration, etc.) together with higher nitrogen balance index (NBI) and lower flavonols and anthocyanins. At 21 days post infection with Fusarium, M. guilliermondii was found to reduce the disease incidence and the severity, with reduction rates reaching up to 31.2% and 30.4%, respectively, as well as to alleviate the disease damaging impact on photosynthesis and plant growth. This was associated with lower ABA, flavonols and anthocyanins, compared to infected control. A pivotal function of M. guilliermondii as an antagonist of F. culmorum and a growth promoter is discussed.

Evaluation of Multifarious Plant Growth Promoting Trials of Yeast Isolated from the Soil of Assam Tea (Camellia sinensis var. assamica) Plantations in Northern Thailand

Some soil microorganisms, especially bacteria and mycorrhizal fungi, play a role in the promotion of plant growth. However, plant growth promotion involving yeasts in soil has not yet been extensively investigated. This study aimed to isolate and identify yeast strains obtained from soils of the Assam tea plant (Camellia sinensis var. assamica) in northern Thailand and to investigate their plant growth promoting capabilities. A total of 42 yeast strains were obtained and identified by analysis of the D1/D2 domain of the large subunit ribosomal RNA gene. We identified 35 strains of six species belonging to the phylum Ascomycota, namely Aureobasidium melanogenum, Kazachstania aquatica, Saturnispora diversa, Saturnispora sekii, Schwanniomyces pseudopolymorphus and Wickerhamomyces anomalus, and six species were determined to belong to the phylum Basidiomycota, namely Apiotrichum scarabaeorum, Curvibasidium pallidicorallinum, Papiliotrema laurentii, Rhodosporidiobolus ruineniae, Trichosporon asahii and Trichosporon coremiiforme. Seven strains were representative of potential new species and belonged to the genera Galactomyces and Wickerhamomyces. A total of 28 strains were found to produce indole-3-acetic acid (IAA) in a range of 2.12 to 37.32 mg/L, with the highest amount of IAA produced by R. ruineniae SDBR-CMU-S1-03. All yeast strains were positive in terms of ammonia production, and only eight strains were positive for siderophore production. Two yeast species, P. laurentii and W. anomalus, were able to solubilize the insoluble form of calcium and zinc. The ability to produce amylase, endogulcanase, lipase, pectinase, protease and xylanase was dependent upon the yeast species and strain involved.

The effect of Saccharomyces cerevisiae on antioxidant system of grape leaves infected by downy mildew

In this article, results of the comparative analysis and assessment of resistance of two grape cultivars Vostorg and Muscat blanc against downy mildew disease (Plasmopara viticola) with or without the symbiote Saccharomyces cerevisiae (vine yeast) were shown. The highly resistant cultivar Vostorg with yeast pre-treatment demonstrated a high defensive capability to the pathogen due to the fast immune response. On the first day after inoculation with downy downy mildew the rapid increase in the hydrogen peroxide, which is involved the first step of the grape’s defense system induction, was observed. At the same time, the upregulation of the relative expression of the PR2 protein (β-1,3-gluconase), a key gene involved in the plant’s resistance to pathogens. The oxidative burst was not detected in the susceptible cultivar Muscat blanc for the couple of hours after inoculation with downy mildew pathogen. The significant increase of the total phenols content and expression of stilbene synthase, which is an enzyme involved in the synthesis of phytoalexins, was observed in leaves of Muscat blanc. It was shown that pre-treatment of grape leaves with natural symbiote S. cerevisiae enhanced the immune response of the resistant cultivar Vostorg and inducted phytoalexins synthesis in the susceptible cultivar Muscat blanc.