Synthesis of Indoleacetic Acid, Gibberellic Acid and ACC-Deaminase by Mortierella Strains Promote Winter Wheat Seedlings Growth under Different Conditions

The endogenous pool of phytoregulators in plant tissues supplied with microbial secondary metabolites may be crucial for the development of winter wheat seedlings during cool springs. The phytohormones may be synthesized by psychrotrophic microorganisms in lower temperatures occurring in a temperate climate. Two fungal isolates from the Spitzbergen soils after the microscopic observations and “the internal transcribed spacer” (ITS) region molecular characterization were identified as Mortierella antarctica (MA DEM7) and Mortierella verticillata (MV DEM32). In order to study the synthesis of indoleacetic acid (IAA) and gibberellic acid (GA), Mortierella strains were grown on media supplemented with precursor of phytohormones tryptophan at 9, 15 °C, and 20 °C for nine days. The highest amount of IAA synthesis was identified in MV DEM32 nine-day-culture at 15 °C with 1.5 mM of tryptophan. At the same temperature (15 °C), the significant promoting effect (about 40% root and shoot fresh weight) of this strain on seedlings was observed. However, only MA DEM-7 had the ACC (1-aminocyclopropane-1-carboxylate) deaminase activity with the highest efficiency at 9 °C and synthesized IAA without tryptophan. Moreover, at the same conditions, the strain was confirmed to possess the strong promoting effect (about 40% root and 24% shoot fresh weight) on seedlings. Both strains synthesized GA in all tested terms and temperatures. The studied Mortierella strains had some important traits that led them to be considered as microbial biofertilizers components, improving plant growth in difficult temperate climates

Mortierella Species as the Plant Growth-Promoting Fungi Present in the Agricultural Soils

In the most recent scientific reports based on the DNA or RNA-analyses a widespread presence of the filamentous fungi, Mortierella in various environments has been shown. Some strains of this genus belong to the plant growth-promoting fungi (PGPF) and are found in the bulk soil, rhizosphere and plants tissues. These microorganisms are also often found in the extremely hostile environments, responsible for improving access to the bioavailable forms of P and Fe in the soils, the synthesis of phytohormones and 1-aminocyclopropane-1-carboxylate (ACC) deaminase, and last but not least the protection of agricultural plants from pathogens. Furthermore, earlier reports classified Mortierella spp. as the saprotrophic microorganisms isolated from the forest litter, and nowadays their status as a very valuable decomposers in the agricultural soils was confirmed. The key features like the ability to survive under very unfavorable environmental conditions and the utilization of carbon sources contained in polymers like cellulose, hemicellulose, chitin make these fungi efficient as the agricultural inoculants. The growing interest in the application of Mortierella spp. is mainly due to the potential use of this genus in the increase of the nutrient uptake efficiency, positive effect in crop protection against adverse conditions, and reduction of chemical fertilizers and pesticides applied. Moreover, activities of Mortierella species selected from the wild or cultivated plants influence the soil microbiota and support the performance of the beneficial microorganisms enhancing significantly crop yield

<i>Trichoderma</i>: The Current Status of Its Application in Agriculture for the Biocontrol of Fungal Phytopathogens and Stimulation of Plant Growth

Rhizosphere filamentous fungi of the genus Trichoderma, a dominant component of various soil ecosystem mycobiomes, are characterized by the ability to colonize plant roots. Detailed knowledge of the properties of Trichoderma, including metabolic activity and the type of interaction with plants and other microorganisms, can ensure its effective use in agriculture. The growing interest in the application of Trichoderma results from their direct and indirect biocontrol potential against a wide range of soil phytopathogens. They act through various complex mechanisms, such as mycoparasitism, the degradation of pathogen cell walls, competition for nutrients and space, and induction of plant resistance. With the constant exposure of plants to a variety of pathogens, especially filamentous fungi, and the increased resistance of pathogens to chemical pesticides, the main challenge is to develop biological protection alternatives. Among non-pathogenic microorganisms, Trichoderma seems to be the best candidate for use in green technologies due to its wide biofertilization and biostimulatory potential. Most of the species from the genus Trichoderma belong to the plant growth-promoting fungi that produce phytohormones and the 1-aminocyclopropane-1-carboxylate (ACC) deaminase enzyme. In the present review, the current status of Trichoderma is gathered, which is especially relevant in plant growth stimulation and the biocontrol of fungal phytopathogens

Plant Tolerance to Drought Stress in the Presence of Supporting Bacteria and Fungi: An Efficient Strategy in Horticulture

Increasing temperature leads to intensive water evaporation, contributing to global warming and consequently leading to drought stress. These events are likely to trigger modifications in plant physiology and microbial functioning due to the altered availability of nutrients. Plants exposed to drought have developed different strategies to cope with stress by morphological, physiological, anatomical, and biochemical responses. First, visible changes influence plant biomass and consequently limit the yield of crops. The presented review was undertaken to discuss the impact of climate change with respect to drought stress and its impact on the performance of plants inoculated with plant growth-promoting microorganisms (PGPM). The main challenge for optimal performance of horticultural plants is the application of selected, beneficial microorganisms which actively support plants during drought stress. The most frequently described biochemical mechanisms for plant protection against drought by microorganisms are the production of phytohormones, antioxidants and xeroprotectants, and the induction of plant resistance. Rhizospheric or plant surface-colonizing (rhizoplane) and interior (endophytic) bacteria and fungi appear to be a suitable alternative for drought-stress management. Application of various biopreparations containing PGPM seems to provide hope for a relatively cheap, easy to apply and efficient way of alleviating drought stress in plants, with implications in productivity and food condition

Physiological Diversity of Spitsbergen Soil Microbial Communities Suggests Their Potential as Plant Growth-Promoting Bacteria

The objective of the study was to assess the physiological diversity and metabolic activity of the soil bacterial communities inhabiting Spitsbergen soils in search of bacterial abilities facilitating plant growth promotion. In the soil, the total number of culturable microorganisms, the number of their individual physiological groups (including Siderophore Synthesizing; SSB and Phosphate Solubilizing Bacteria; PSB), the dehydrogenase (DH) activity, and the ability to utilize sources of C, N, P (EcoPlate) were analysed. In bacterial isolates, siderophores production, ACC (1-aminocyclopropane-1-carboxylate) deaminase (ACCD) activity, IAA (indole-3-acetic acid) synthesis were examined. The isolates were applied to the seeds of Phaseolus coccineus regarding their germination and root length. The results showed differences between copio- and oligotrophic bacteria. A usually high number of SSB was accompanied by the raised number of PSB. A bigger number of SSB was connected with low values of Fe in the soil. High DH activity was assisted by greater number of copio- and oligotrophic bacteria, raised average well color development value, and N and C contents in the soil. Germination index was more alike relative seed germination than relative root growth. IAA concentration and ACCD activity were conversely related. Synthesis of siderophores was matched with ACCD activity and its high level was combined with elevated germination index. In spite of different localization of soil samples, some isolates proved similar traits of activity. Distinct affiliation of isolates and their various localizations were displayed. Among all isolates tested, some possessed one main trait of activity, but most of them had two or more significant features for potential plant growth stimulation. These isolates could be an important source of useful bacteria

Bacterial Isolate Inhabiting Spitsbergen Soil Modifies the Physiological Response of <i>Phaseolus coccineus</i> in Control Conditions and under Exogenous Application of Methyl Jasmonate and Copper Excess

The aim of the study was to demonstrate the potential of the promotion and regulation of plant physiology and growth under control and copper stress conditions, and the impact of the exogenous application of methyl jasmonate on this potential. Runner bean plants were treated with methyl jasmonate (1 or 10 &#181;M) (J; J1 or J10) and Cu (50 &#181;M), and inoculated with a bacterial isolate (S17) originating from Spitsbergen soil, and identified as Pseudomonas luteola using the analytical profile index (API) test. Above- and under-ground plant parts were analyzed. The growth parameters; the concentration of the photosynthetic pigments, elements, flavonoids (FLAVO), phenolics (TPC), allantoin (ALLA), and low molecular weight organic acids (LMWOAs); the activity of antioxidant enzymes and enzymes of resistance induction pathways (e.g., superoxide dismutase (SOD), catalase (CAT), ascorbate (APX) and guaiacol (GPX) peroxidase, glucanase (GLU), and phenylalanine (PAL) and tyrosine ammonia-lyase (TAL)), and the antioxidant capacity (AC) were studied. The leaves exhibited substantially higher ALLA and LMWOA concentrations as well as PAL and TAL activities, whereas the roots mostly had higher activities for a majority of the enzymes tested (i.e., SOD, CAT, APX, GPX, and GLU). The inoculation with S17 mitigated the effect of the Cu stress. Under the Cu stress and in the presence of J10, isolate S17 caused an elevation of the shoot fresh weight, K concentration, and TAL activity in the leaves, and APX and GPX (also at J1) activities in the roots. In the absence of Cu, isolate S17 increased the root length and the shoot-to-root ratio, but without statistical significance. In these conditions, S17 contributed to a 236% and 34% enhancement of P and Mn, respectively, in the roots, and a 19% rise of N in the leaves. Under the Cu stress, S17 caused a significant increase in FLAVO and TPC in the leaves. Similarly, the levels of FLAVO, TPC, and AC were enhanced after inoculation with Cu and J1. Regardless of the presence of J, inoculation at Cu excess caused a reduction of SOD and CAT activities, and an elevation of GPX. The effects of inoculation were associated with the application of Cu and J, which modified plant response mainly in a concentration-dependent manner (e.g., PAL, TAL, and LMWOA levels). The conducted studies demonstrated the potential for isolate S17 in the promotion of plant growth

Synthesis of Indoleacetic Acid, Gibberellic Acid and ACC-Deaminase by Mortierella Strains Promote Winter Wheat Seedlings Growth under Different Conditions

The endogenous pool of phytoregulators in plant tissues supplied with microbial secondary metabolites may be crucial for the development of winter wheat seedlings during cool springs. The phytohormones may be synthesized by psychrotrophic microorganisms in lower temperatures occurring in a temperate climate. Two fungal isolates from the Spitzbergen soils after the microscopic observations and &ldquo;the internal transcribed spacer&rdquo; (ITS) region molecular characterization were identified as Mortierella antarctica (MA DEM7) and Mortierella verticillata (MV DEM32). In order to study the synthesis of indoleacetic acid (IAA) and gibberellic acid (GA), Mortierella strains were grown on media supplemented with precursor of phytohormones tryptophan at 9, 15 &deg;C, and 20 &deg;C for nine days. The highest amount of IAA synthesis was identified in MV DEM32 nine-day-culture at 15 &deg;C with 1.5 mM of tryptophan. At the same temperature (15 &deg;C), the significant promoting effect (about 40% root and shoot fresh weight) of this strain on seedlings was observed. However, only MA DEM-7 had the ACC (1-aminocyclopropane-1-carboxylate) deaminase activity with the highest efficiency at 9 &deg;C and synthesized IAA without tryptophan. Moreover, at the same conditions, the strain was confirmed to possess the strong promoting effect (about 40% root and 24% shoot fresh weight) on seedlings. Both strains synthesized GA in all tested terms and temperatures. The studied Mortierella strains had some important traits that led them to be considered as microbial biofertilizers components, improving plant growth in difficult temperate climates

Phytohormones (Auxin, Gibberellin) and ACC Deaminase In Vitro Synthesized by the Mycoparasitic Trichoderma DEMTkZ3A0 Strain and Changes in the Level of Auxin and Plant Resistance Markers in Wheat Seedlings Inoculated with this Strain Conidia

Both hormonal balance and plant growth may be shaped by microorganisms synthesizing phytohormones, regulating its synthesis in the plant and inducing plant resistance by releasing elicitors from cell walls (CW) by degrading enzymes (CWDE). It was shown that the Trichoderma DEMTkZ3A0 strain, isolated from a healthy rye rhizosphere, colonized the rhizoplane of wheat seedlings and root border cells (RBC) and caused approximately 40% increase of stem weight. The strain inhibited (in over 90%) the growth of polyphagous Fusarium spp. (F. culmorum, F. oxysporum, F. graminearum) phytopathogens through a mechanism of mycoparasitism. Chitinolytic and glucanolytic activity, strongly stimulated by CW of F. culmorum in the DEMTkZ3A0 liquid culture, is most likely responsible for the lysis of hyphae and macroconidia of phytopathogenic Fusarium spp. as well as the release of plant resistance elicitors. In DEMTkZ3A0 inoculated plants, an increase in the activity of the six tested plant resistance markers and a decrease in the concentration of indoleacetic acid (IAA) auxin were noted. IAA and gibberellic acid (GA) but also the 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase (ACCD) enzyme regulating ethylene production by plant were synthesized by DEMTkZ3A0 in the liquid culture. IAA synthesis was dependent on tryptophan and negatively correlated with temperature, whereas GA synthesis was positively correlated with the biomass and temperature

Cholesterol affects spectrin-phospholipid interactions in a manner different from changes resulting from alterations in membrane fluidity due to fatty acyl chain composition

AbstractWe previously showed that erythrocyte and brain spectrins bind phospholipid vesicles and monolayers prepared from phosphatidylethanolamine and phosphatidylserine and their mixtures with phosphatidylcholine (Review: A.F. Sikorski, B. Hanus-Lorenz, A. Jezierski, A. R. Dluzewski, Interaction of membrane skeletal proteins with membrane lipid domain, Acta Biochim. Polon. 47 (2000) 565). Here, we show how changes in the fluidity of the phospholipid monolayer affect spectrin–phospholipid interaction. The presence of up to 10%–20% cholesterol in the PE/PC monolayer facilitates the penetration of the monolayer by both types of spectrin. For monolayers constructed from mixtures of PI/PC and cholesterol, the effect of spectrins was characterised by the presence of two maxima (at 5 and 30% cholesterol) of surface pressure for erythroid spectrin, and a single maximum (at 20% cholesterol) for brain spectrin. The binding assay results indicated a small but easily detectable decrease in the affinity of erythrocyte spectrin for FAT-liposomes prepared from a PE/PC mixture containing cholesterol, and a 2- to 5-fold increase in maximal binding capacity (Bmax) depending on the cholesterol content. On the other hand, the results from experiments with a monolayer constructed from homogenous synthetic phospholipids indicated an increase in Δπ change with the increase in the fatty acyl chain length of the phospholipids used to prepare the monolayer. This was confirmed by the results of a pelleting experiment. Adding spectrins into the subphase of raft-like monolayers constructed from DOPC, SM and cholesterol (1/1/1) induced an increase in surface pressure. The Δπ change values were, however, much smaller than those observed in the case of a natural PE/PC (6/4) monolayer. An increased binding capacity for spectrins of liposomes prepared from a “raft-like” mixture of lipids could also be concluded from the pelleting assay. In conclusion, we suggest that the effect of membrane lipid fluidity on spectrin–phospholipid interactions is not simple but depends on how it is regulated, i.e., by cholesterol content or by the chemical structure of the membrane lipids