Acidic soils rapidly retain applied phosphorus fertilizers and consequently present low availability of this nutrient to plants. The use of phosphate-solubilizing microorganisms to help plant phosphorus (P) absorption is a promising sustainable strategy for managing P deficiencies in agricultural soils. Trichoderma strains have been one of the most studied filamentous fungi for improving the production and development of several crop species mainly due to their capability for symbiotic associations and their ability to control soil-borne plant diseases. Thus, this work sought to bioprospect Trichoderma strains from the Amazon rainforest capable of solubilizing/mineralizing soil phosphate and promoting soybean growth. Soybean plants inoculated with selected Trichoderma strains were cultivated in soil under greenhouse conditions and under a gradient of rock phosphate and triple superphosphate. As a result, 19.5% of the isolated Trichoderma strains were able to solubilize phosphate. In addition, those strains produced different organic acids during the solubilization process. Trichoderma spp. strains showed positive responses in the promotion of soybean growth-from 2.1% to 41.1%-as well as in the efficiency of P uptake-up to 141%. These results reveal the potential of Trichoderma spp. from the Amazon biome as promising biofertilizer agents.

/pdf/phosphorus-solubilizing-trichoderma-spp-from-amazon-soils-32dbj5zbkt.pdf

Phosphorus-solubilizing Trichoderma spp. from Amazon soils improve soybean plant growth

Members of the fungal genus Trichoderma (Ascomycota, Hypocreales, Hypocreaceae) are ubiquitous and commonly encountered as soil inhabitants, plant symbionts, saprotrophs, and mycoparasites. Certain species have been used to control diverse plant diseases and mitigate negative growth conditions. The versatility of Trichoderma’s interactions mainly relies on their ability to engage in inter- and cross-kingdom interactions. Although Trichoderma is by far the most extensively studied fungal biocontrol agent (BCA), with a few species already having been commercialized as bio-pesticides or bio-fertilizers, their wide application has been hampered by an unpredictable efficacy under field conditions. Deciphering the dialogues within and across Trichoderma ecological interactions by identification of involved effectors and their underlying effect is of great value in order to be able to eventually harness Trichoderma’s full potential for plant growth promotion and protection. In this review, we focus on the nature of Trichoderma interactions with plants and pathogens. Better understanding how Trichoderma interacts with plants, other microorganisms, and the environment is essential for developing and deploying Trichoderma-based strategies that increase crop production and protection.

Deciphering Trichoderma-Plant-Pathogen Interactions for Better Development of Biocontrol Applications.

Phosphate solubilization by Trichoderma koningiopsis (NBRI-PR5) under abiotic stress conditions

Trichoderma bridges waste biomass and ultra-high specific surface area carbon to achieve a high-performance supercapacitor

Trichoderma species are known as excellent biocontrol agents against soil-borne pathogens that cause considerable crop losses. Eight strains of Trichoderma were isolated from five Egyptian regions. They identified based on translation elongation factor-1α (TEF1) sequencing as four different Trichoderma species: Trichoderma asperellum, Trichoderma harzianum, Trichoderma viride, and Trichoderma longibrachiatum. Optimal growth conditions (temperature and media), and the phosphate solubilization capability of Trichoderma strains were evaluated in vitro. Further, the ability of these strains to antagonize Fusarium solani, Macrophomina phaseolina, and Fusarium graminearum was also evaluated. The results revealed that Trichoderma harzianum (Th6) exhibited the highest antagonistic ability against F. solani, M. phaseolina and F. graminearum with inhibition rates of 71.42%, 72.97%, and 84.61%, respectively. Trichoderma viride (Tv8) exhibited the lowest antagonism against the same pathogens with inhibition rates of 50%, 64% and 69.23%, respectively. Simple-sequence repeats (SSRs) and random amplified polymorphic DNA (RAPD) markers were used to evaluate the genetic variability of the Trichoderma strains. The results revealed that of 45 RAPD amplified bands, 36 bands (80%) were polymorphic and of SSRs amplified 36 bands, 31 bands (86.11%) were polymorphic. The amplification of calmodulin and β-1,3-endoglucanase was noted at 500 bp and 230 bp, respectively. Data indicated that T. viride (Tv8) had the highest phosphate solubilization index (10.0 mm), while T. harzianum (Th6) had the lowest phosphate solubilization index (4.0 mm). In conclusion, T. harzianum (Th6) had the highest antagonistic activity in dual culture assay along with the growth rate; while T. viride (Tv8) had the highest phosphate solubilization activity. There are still gaps in obtaining new formulations, selecting potent Trichoderma strains to confirm disease control in planta. For improving Trichoderma recommendation in the organic agricultural system and sustaining the fertility of the soil, the field application of highly antagonistic biocontrol agents in different types of soil and plant species will be the first approach toward bio-pesticide treatments along with bio-fertilizer inoculation. Furthermore, secondary metabolites will be investigated for the most promising strains with the combination of different pathogens and application timing.

https://www.mdpi.com/2079-7737/9/8/189/pdf

Phylogenetic Diversity of Trichoderma Strains and Their Antagonistic Potential against Soil-Borne Pathogens under Stress Conditions

Interaction of plant growth promoting microorganisms (PGPMs) with plants involves interplay at physical, physiological and molecular levels. Proliferation and root colonization of PGPMs manipulate the rhizosphere to optimize plant functions. This benefits plant by nutrient enrichment and induction of plant vigor and defense system. The present work aims to decipher the rhizosphere modulations promoted under different fertilization regimes by an organic acid producing Trichoderma koningiopsis strain (NBRI-PR5). Chickpea was selected as the host plant for the study since it responds well to the application of in/organic fertilizers and PGPMs. Microbial communities associated with the rhizosphere were studied by determining culturable population of heterogeneous microflora, and rhizosphere functions were studied by determining the soil enzyme activities and HPLC profiles of organic acids in root exudates. Application of NBRI-PR5 induced changes in rhizosphere in consent with the amendments. The changes observed in microbial populations were found to be associated with the rhizosphere enzymes. The inhibitory effect of chemical fertilizers on rhizosphere microflora was evident from least bacterial CFU observed in the NPK treatments. No detection of alkaline phosphatase enzyme in all the treatments with NBRI-PR5, with organic or inorganic amendments evidently represents the acidified rhizosphere. Similarly, an opposite trend in DHA and protease enzyme activities in the rhizosphere of FYM and FYM+PR5 treated plants showed that NBRI-PR5 had reframed microbial activities to facilitate nutrient uptake in plants rather than fix in the microbes. It is concluded from the study that NBRI-PR5 fatefully modulates rhizosphere activities, specific to different fertilization regimes by varying the enzyme activities to maximize the utilization of available nutrients.

/pdf/effect-of-trichoderma-koningiopsis-on-chickpea-rhizosphere-5ecw907yoz.pdf

Effect of Trichoderma koningiopsis on Chickpea Rhizosphere Activities under Different Fertilization Regimes

Role of microorganism as new generation plant bio-stimulants: An assessment

Dengue Virus (DENV) is a mosquito-borne virus that is prevalent in the world's tropical and subtropical regions. Therefore, early detection and surveillance can help in the management of this disease. Current diagnostic methods rely primarily on ELISA, PCR, and RT-PCR, among others, which can only be performed in specialized laboratories and require sophisticated instruments and technical expertise. CRISPR-based technologies on the other hand have field-deployable viral diagnostics capabilities that could be used in the development of point-of-care molecular diagnostics. The first step in the field of CRISPR-based virus diagnosis is to design and screen gRNAs for high efficiency and specificity. In the present study, we employed a bioinformatics approach to design and screen DENV CRISPR/Cas13 gRNAs for conserved and serotype-specific variable genomic regions in the DENV genome. We identified one gRNA sequence specific for each of the lncRNA and NS5 regions and identified one gRNA against each of DENV1, DENV2, DENV3, and DENV4 to distinguish the four DENV serotypes. These CRISPR/Cas13 gRNA sequences will be useful in diagnosing the dengue virus and its serotypes for in vitro validation and diagnostics.

/pdf/towards-the-diagnosis-of-dengue-virus-and-its-serotypes-kr9aica0.pdf

Towards the diagnosis of dengue virus and its serotypes using designed CRISPR/Cas13 gRNAs

Land degradation has built up silently and progressively, leading to deterioration of soil health to a point unfit for crop cultivation. It manifests in various forms such as sodicity, acidity, soil erosion, and heavy metal and pesticide contamination. The diminishing soil health is aggravated by depletion of soil organic carbon and nutrients, which results in an unstable foundation upon which the pillars of food security cannot be laid down. Management strategies with emphasis on sustainable carbon and nutrient sequestration potential are thus needed to strengthen the nexus between soil and agricultural productivity. Microbes, being indispensable components of soil, play an important role in reinforcing soil fertility, structural organization, and biogeochemical cycling. The potential of microbial diversity has been exploited to develop strategies and technologies to improve the soil properties. Various facets of microbe-mediated soil health restoration strategies in sustainable management of degraded lands have been discussed in the chapter.

Ashmita Tandon

Papers

Phosphate solubilization by Trichoderma koningiopsis (NBRI-PR5) under abiotic stress conditions

Effect of Trichoderma koningiopsis on Chickpea Rhizosphere Activities under Different Fertilization Regimes

Role of microorganism as new generation plant bio-stimulants: An assessment

Towards the diagnosis of dengue virus and its serotypes using designed CRISPR/Cas13 gRNAs

Microbe-mediated management of degraded and marginal lands