Endophyte Piriformospora Indica Research Articles

An improvement in water stress tolerance in rice by altering morpho-physiological and biochemical mechanisms using root colonizing endophyte Piriformospora indica

An improvement in water stress tolerance in rice by altering morpho-physiological and biochemical mechanisms using root colonizing endophyte Piriformospora indica

Root endophyte Piriformospora indica significantly affects mechanisms involved in mitigating drought stress in rice (Oryza sativa)

An experiment was conducted during the summer season of 2020 at College of Agriculture, Kerala Agricultural University, Vellayani to study the potential of a beneficial root endophyte Piriformospora indica Sav. Verma, Aj. Varma, Rexer G. Kost & P. Franken in mitigating drought stress in rice (Oryza sativa L.). The field experiment was undertaken in the lowland paddy fields with sandy clay loam texture in randomized block design. Treatments were Piriformospora indica colonized and non-colonized rice seedlings under 3 irrigation intervals of 30 mm, 35 mm and 40 mm cumulative pan evaporation and 2 irrigation depths of 1.5 cm and 3 cm. Plants colonized with P. indica significantly enhanced the yield attributes and root parameters. This symbiotic association alleviated the negative effects of drought stress by maintaining higher proline content (71.8 μmole/g) and relative leaf water content (74%) irrespective of interval and depth of irrigation. Colonization boosted the uptake of phosphorus and maintained higher chlorophyll stability index (79.20%). Yield attributes of P. indica colonized plants subjected to severe stress, were observed to be equivalent to those of non-colonized plants under moderate stress and association with the endophyte resulted in saving of 30 mm water and could help rice to combat drought stress. Higher phosphorus uptake enhanced the root volume (29.1cm3 ) under severe water stress facilitated improved nutrient uptake (10.6 kg/ ha) from deeper layers of soil for colonized plants compared to the control plants and acted as a mitigating mechanism against drought stress.

Beneficial Fungal Root Endophyte Piriformospora indica Diminishes Yield Loss Without Compromising Quality of Banana Fruits Due to Banana bract mosaic virus Infection through Better Soil Nutrient Mobilization

Aims: Banana bract mosaic virus (BBrMV) is a significant viral disease that adversely impacts the yield and quality of banana (Musa acuminata) fruits. Endophytes have been recognized as a sustainable tool to enhance plant nutrient availability and uptake. Piriformospora indica is a beneficial fungal root endophyte that can improve nutrient utilization and confer tolerance to diverse abiotic and biotic stresses in banana plants. The effect of P. indica colonization on nutrient assimilation and fruit quality of BBrMV-infected banana plants still needs to be better understood, particularly in the humid tropical environments of southern laterites of Kerala. P. indica promotes both fruit size and quality, leading to an overall improvement of fruit attributes viz., fruit length, width, colour, TSS, acidity, moisture, and ash content etc., An experiment comprising four treatments with five replications revealed that P. indica colonization enhanced potassium concentration at the rhizosphere (603 Kg ha-1), whereas decreased in the diseased plants (318 Kg ha-1). The nutrient concentration in the rhizosphere recorded a substantial relation with disease severity. Compared to P. indica colonized plants, the uptake of N, P, K, Ca, Mg, S and B by BBrMV infected plants exhibited 36.5, 37.6, 57.5, 44.1, 23.3, 43.7 and 48.9 per cent reduction respectively. Hence, pre-colonization of P. indica improved the nutrient mobilization (in soil), uptake and accumulation (in fruit) in the BBrMV infected banana plants compared to the virus alone infected plant. Fruits from P. indica pre-colonized plants challenged with the virus exhibited an enhanced K (515.5 ± 6.25 mg 100g -1) and Fe (0.42 ± 0.04 mg 100 g-1) content along with high total soluble sugars (27.25oBrix), titrable acidity (0.48%) and ash content (1.14%) compared to healthy and virus infected plants. Hence, this can instigate the appropriate sustainable virus disease management strategies in banana plants, emphasizing its improved fruit quality through nutrient assimilation.

Unravelling the Role of Piriformospora indica in Combating Water Deficiency by Modulating Physiological Performance and Chlorophyll Metabolism-Related Genes in Cucumis sativus

Water stress is the most critical aspect restricting the development of agriculture in regions with scarce water resources, which requires enhancing irrigation water-saving strategies. The current work discusses the potential application of the plant-strengthening root endophyte Piriformospora indica against moderate (25% less irrigation water) and severe (50% less irrigation water) water stress in comparison to the optimum irrigation conditions of greenhouse cucumbers. P. indica improved growth, nutrient content, and photosynthesis apparatus under normal or water-stress conditions. On the other hand, moderate and severe water stress reduced yield up to 47% and 83%, respectively, in non-colonized cucumber plants, while up to 28 and 78%, respectively, in P. indica-colonized plants. In terms of water-use efficiency (WUE), P. indica improved the WUE of colonized cucumber plants grown under moderate (26 L/kg) or severe stress (73 L/kg) by supporting colonized plants in producing higher yield per unit volume of water consumed by the crop in comparison to non-colonized plants under the same level of moderate (43 L/kg) or severe (81 L/kg) water stress. Furthermore, P. indica increased the indole-3-acetic acid (IAA) content, activity levels of catalase (CAT) and peroxidase (POD) with an apparent clear reduction in the abscisic acid (ABA), ethylene, malondialdehyde (MDA), proline contents and stomatal closure compared to non-stressed plants under both water-stress levels. In addition, chlorophyll a, b, a + b contents were increased in the leaves of the colonized plants under water-stress conditions. This improvement in chlorophyll content could be correlated with a significant increment in the transcripts of chlorophyll biosynthesis genes (protochlorophyllide oxidoreductase [POR], chlorophyll a oxygenase [CAO]) and a reduction in the chlorophyll degradation genes (PPH, pheophorbide a oxygenase [PAO], and red chlorophyll catabolite reductase [RCCR]). In conclusion, P. indica has the potential to enhance the cucumber yield grown under moderate water stress rather than severe water stress by improving WUE and altering the activity levels of antioxidant enzymes and chlorophyll metabolism-related genes.

Endophytes: Colonization, Behaviour, and Their Role in Defense Mechanism

Biotic and abiotic factors cause an enormous amount of yield and economical loss. However, endophytes can play a significant role in enhancing the tolerance of plants. Endophytes systematically colonize different parts of the host, but plants use a variety of defense mechanisms towards microbial infection. However, they have to survive the oxidative environments, and endophytes like Enterobacter sp. encode superoxide dismutases, catalases, and hydroperoxide reductases to cope up the oxidative stress during colonization. On the contrary, others produce subtilomycin which binds with flagella to affect flg22-induced plant defense. The behavior of endophytes can be affected by different genes in hydrolase activity when they come into contact with the host plant. The lifestyle of endophytes is influenced by environmental factors, the host, and microbial genotypes, as well as an imbalance in nutrient exchange between the microbe and the host. For instance, induction of PiAMT1 in root endophyte Piriformospora indica indicates depletion of nitrogen which plays as a triggering factor for activation of the saprotrophic program. Microbes enhance disease resistance through induced systemic resistance (ISR), and Bacillus cereus triggers ISR against Botrytis cinerea through an accumulation of the PR1 protein and activates MAPK signaling and WRKY53 gene expression by the JA/ET signaling pathway. Similarly, Trichoderma arundinaceum produces trichodiene that affects Botrytis cinerea through induction of defense-related genes encoding salicylic acid (SA) and jasmonate (JA). Overall, endophytes can play a vital role in disease management.

Colonisation of Oncidium orchid roots by the endophyte Piriformospora indica restricts Erwinia chrysanthemi infection, stimulates accumulation of NBS-LRR resistance gene transcripts and represses their targeting micro-RNAs in leaves

BackgroundErwinia chrysanthemi (Ec) is a destructive pathogen which causes soft-rot diseases in diverse plant species including orchids. We investigated whether colonization of Oncidium roots by the endophytic fungus Piriformospora indica (Pi) restricts Ec-induced disease development in leaves, and whether this might be related to the regulation of nucleotide binding site-leucine rich repeat (NBS-LRR) Resistance (R) genes.ResultsRoot colonization of Oncidium stackings by Pi restricts progression of Ec-induced disease development in the leaves. Since Pi does not inhibit Ec growth on agar plates, we tested whether NBS-LRR R gene transcripts and the levels of their potential target miRNAs in Oncidium leaves might be regulated by Pi. Using bioinformatic tools, we first identified NBS-LRR R gene sequences from Oncidium, which are predicted to be targets of miRNAs. Among them, the expression of two R genes was repressed and the accumulation of several regulatory miRNA stimulated by Ec in the leaves of Oncidium plants. This correlated with the progression of disease development, jasmonic and salicylic acid accumulation, ethylene synthesis and H2O2 production after Ec infection of Oncidium leaves. Interestingly, root colonization by Pi restricted disease development in the leaves, and this was accompanied by higher expression levels of several defense-related R genes and lower expression level of their target miRNA.ConclusionBased on these data we propose that Pi controls the levels of NBS-LRR R mRNAs and their target miRNAs in leaves. This regulatory circuit correlates with the protection of Oncidium plants against Ec infection, and molecular and biochemical investigations will demonstrate in the future whether, and if so, to what extent these two observations are related to each other.

Growth promotion and disease resistance induced in Anthurium colonized by the beneficial root endophyte Piriformospora indica

BackgroundAnthurium andraeanum, an important ornamental flower, has to go through a growth-delaying period after transfer from tissue culture to soil, which requires time and extra costs. Furthermore, during this period, the plantlets are highly susceptible to bacterial infections, which results in impaired development and severe losses. Here, we aimed to address whether application of the endophytic fungus, Piriformospora indica protects the A. andraeanum root system during the critical propagation period, and whether P. indica reduce the mortality rate by stimulating the host’s resistance against diseases.ResultsWe demonstrate that P. indica shortens the recovery period of Anthurium, promotes growth and confers disease resistance. The beneficial effect of P. indica results in faster elongation of Anthurium roots early in the interaction. P. indica-colonized plants absorb more phosphorus and exhibit higher photosynthesis rates than uncolonized control plants. Moreover, higher activities of stress-related enzymes, of jasmonic acid levels and mRNA levels of jasmonic acid-responsive genes suggest that the fungus prepares the plant to respond more efficiently to potentially upcoming threats, including bacterial wilt.ConclusionThese results suggest that P. indica is a helpful symbiont for promoting Anthurium rooting and development. All our evidences are sufficient to support the disease resistance conferred by P. indica through the plant-fungal symbiosis. Furthermore, it implicates that P. indica has strong potential as bio-fertilizer for utilization in ornamental plant cultivation.

Root endophytic fungus Piriformospora indica improves drought stress adaptation in barley by metabolic and proteomic reprogramming

The root fungal endophyte Piriformospora indica promotes the growth and survival of plants belonging to a number of species when exposed to various abiotic stresses, including drought, a major constraint of crop productivity. The application of 'omics technologies has revealed much of the molecular basis of the plant drought stress response. Here, the proteomic and metabolomic response of the leaves of moisture-stressed barley plants inoculated with P. indica was characterized. The abundance of 145 proteins was altered by the imposition of moderate drought on plants inoculated by P. indica, as was that of 104 in non-inoculated plants, while an episode of more severe stress altered the content of, respectively, 144 and 462 proteins. Many of these responsive proteins were involved in the plant’s primary metabolism, in particular acting to mitigate the damage caused by oxidative stress. Colonization of the roots by P. indica enhanced the activity of both the photosystem and the electron transfer chain, and also promoted the accumulation of proteins protective of photorespiration, energy modulation, primary metabolism, transporters and autophagy. The beneficial effect of P. indica colonization on autophagy in plants exposed to stress may relate to alterations in the host’s amino acid metabolism.

Inoculation with the endophyte Piriformospora indica significantly affects mechanisms involved in osmotic stress in rice

BackgroundRice is a drought susceptible crop. A symbiotic association between rice and mycorrhizal fungi could effectively protect the plant against sudden or frequent episodes of drought. Due to its extensive network of hyphae, the endophyte is able to deeply explore the soil and transfer water and minerals to the plant, some of them playing an important role in mitigating the effects of drought stress. Moreover, the endophyte could modify the expression of drought responsive genes and regulate antioxidants.ResultsThree rice genotypes, WC-297 (drought tolerant), Caawa (moderately drought tolerant) and IR-64 (drought susceptible) were inoculated with Piriformospora indica (P. indica), a dynamic endophyte. After 20 days of co-cultivation with the fungus, rice seedlings were subjected to 15% polyethylene glycol-6000 induced osmotic stress. P. indica improved the growth of rice seedlings. It alleviated the destructive effects of the applied osmotic stress. This symbiotic association increased seedling biomass, the uptake of phosphorus and zinc, which are functional elements for rice growth under drought stress. It boosted the chlorophyll fluorescence, increased the production of proline and improved the total antioxidant capacity in leaves. The association with the endophyte also up regulated the activity of the Pyrroline-5-carboxylate synthase (P5CS), which is critical for the synthesis of proline.ConclusionA mycorrhizal association between P. indica and rice seedlings provided a multifaceted protection to rice plants under osmotic stress (− 0.295 MPa).

Proteomic approach to understand the molecular physiology of symbiotic interaction between Piriformospora indica and Brassica napus

Many studies have been now focused on the promising approach of fungal endophytes to protect the plant from nutrient deficiency and environmental stresses along with better development and productivity. Quantitative and qualitative protein characteristics are regulated at genomic, transcriptomic, and posttranscriptional levels. Here, we used integrated in-depth proteome analyses to characterize the relationship between endophyte Piriformospora indica and Brassica napus plant highlighting its potential involvement in symbiosis and overall growth and development of the plant. An LC-MS/MS based label-free quantitative technique was used to evaluate the differential proteomics under P. indica treatment vs. control plants. In this study, 8,123 proteins were assessed, of which 46 showed significant abundance (34 downregulated and 12 upregulated) under high confidence conditions (p-value ≤ 0.05, fold change ≥2, confidence level 95%). Mapping of identified differentially expressed proteins with bioinformatics tools such as GO and KEGG pathway analysis showed significant enrichment of gene sets involves in metabolic processes, symbiotic signaling, stress/defense responses, energy production, nutrient acquisition, biosynthesis of essential metabolites. These proteins are responsible for root’s architectural modification, cell remodeling, and cellular homeostasis during the symbiotic growth phase of plant’s life. We tried to enhance our knowledge that how the biological pathways modulate during symbiosis?

Combined effects of fungal inoculants and the cytokinin-like growth regulator thidiazuron on growth, phytohormone contents and endophytic root fungi in Miscanthus × giganteus

Aim of this study was to investigate main effects and interactions between symbiotic fungi and the cytokinin-like growth regulator thidiazuron (TDZ) in Miscanthus × giganteus. The arbuscular mycorrhiza fungus Rhizophagus intraradices (AMF) and the endophyte Piriformospora indica (PI) were chosen as model symbionts. The fungal inoculants and TDZ had no significant effect on plant growth but modulated phytohormone levels in the leaves. TDZ induced accumulation of salicylic acid in controls, but not in plants inoculated with fungi. Leaf concentrations of abscisic acid (ABA) derivatives, auxin (indole-3-acetic acid) precursors and catabolites and numerous cytokinins were increased by R. intraradices but lowered by P. indica. TDZ raised concentrations of ABA compounds, the non-indole auxin phenylacetic acid, jasmonate and some cytokinins, but decreased cis-zeatin and N6-(Δ2-isopentenyl)adenine levels. Inoculation with AMF reduced abundance of endogenous clampless endophytes. TDZ application strongly reduced formation of arbuscular mycorrhiza and increased occurrence of clamped mycelia (i.e. basidiomycetous endophytes). Our study provides a thorough outline of the phytohormone homeostasis under the combined influence of beneficial inoculants and a growth regulator, highlighting the necessity to study their interaction in the whole plant-microbial context.

Colonization by the endophyte Piriformospora indica leads to early flowering in Arabidopsis thaliana likely by triggering gibberellin biosynthesis

Piriformospora indica is an endophytic fungus colonizing roots of a wide variety of plants. Previous studies showed that P. indica promotes early flowering and plant growth in the medicinal plant Coleus forskohlii. To determine the impact of P. indica on flowering time in Arabidopsis, we co-cultivated the plants with P. indica under long day condition. P. indica inoculated Arabidopsis plants displayed significant early flowering phenotype. qRT-PCR analysis of colonized plants revealed an up-regulation of flowering regulatory (FLOWERING LOCUS T, LEAFY, and APETALA1) and gibberellin biosynthetic (Gibberellin 20-Oxidase2, Gibberellin 3-Oxidase1 and Gibberellin requiring1) genes, while the flowering-repressing gene FLOWERING LOCUS C was down regulated. Quantification of gibberellins content showed that the colonization with P. indica caused an increase in GA4 content. Compared to wild-type plants, inoculation of the Arabidopsis ga5 mutant affected in gibberellin biosynthetic gene led to less pronounced changes in the expression of genes regulating flowering and to a lower increase in GA4 content. Taken together, our data indicate that P. indica promotes early flowering in Arabidopsis likely by increasing gibberellin content.

PiHOG1, a stress regulator MAP kinase from the root endophyte fungus Piriformospora indica, confers salinity stress tolerance in rice plants.

In this study, yeast HOG1 homologue from the root endophyte Piriformospora indica (PiHOG1) was isolated and functionally characterized. Functional expression of PiHOG1 in S. cerevisiae ∆hog1 mutant restored osmotolerance under high osmotic stress. Knockdown (KD) transformants of PiHOG1 generated by RNA interference in P. indica showed that genes for the HOG pathway, osmoresponse and salinity tolerance were less stimulated in KD-PiHOG1 compared to the wild-type under salinity stress. Furthermore, KD lines are impaired in the colonization of rice roots under salinity stress of 200 mM NaCl, and the biomass of the host plants, their shoot and root lengths, root number, photosynthetic pigment and proline contents were reduced as compared to rice plants colonized by WT P. indica. Therefore, PiHOG1 is critical for root colonisation, salinity tolerance and the performance of the host plant under salinity stress. Moreover, downregulation of PiHOG1 resulted not only in reduced and delayed phosphorylation of the remaining PiHOG1 protein in colonized salinity-stressed rice roots, but also in the downregulation of the upstream MAP kinase genes PiPBS2 and PiSSK2 involved in salinity tolerance signalling in the fungus. Our data demonstrate that PiHOG1 is not only involved in the salinity response of P. indica, but also helping host plant to overcome salinity stress.

The fungal-specific β-glucan-binding lectin FGB1 alters cell-wall composition and suppresses glucan-triggered immunity in plants.

β-glucans are well-known modulators of the immune system in mammals but little is known about β-glucan triggered immunity in planta. Here we show by isothermal titration calorimetry, circular dichroism spectroscopy and nuclear magnetic resonance spectroscopy that the FGB1 gene from the root endophyte Piriformospora indica encodes for a secreted fungal-specific β-glucan-binding lectin with dual function. This lectin has the potential to both alter fungal cell wall composition and properties, and to efficiently suppress β-glucan-triggered immunity in different plant hosts, such as Arabidopsis, barley and Nicotiana benthamiana. Our results hint at the existence of fungal effectors that deregulate innate sensing of β-glucan in plants.

A fungal endophyte helps plants to tolerate root herbivory through changes in gibberellin and jasmonate signaling.

Summary Plant–microbe mutualisms can improve plant defense, but the impact of root endophytes on below‐ground herbivore interactions remains unknown. We investigated the effects of the root endophyte Piriformospora indica on interactions between rice (Oryza sativa) plants and its root herbivore rice water weevil (RWW; Lissorhoptrus oryzophilus), and how plant jasmonic acid (JA) and GA regulate this tripartite interaction.Glasshouse experiments with wild‐type rice and coi1‐18 and Eui1‐OX mutants combined with nutrient, jasmonate and gene expression analyses were used to test: whether RWW adult herbivory above ground influences subsequent damage caused by larval herbivory below ground; whether P. indica protects plants against RWW; and whether GA and JA signaling mediate these interactions.The endophyte induced plant tolerance to root herbivory. RWW adults and larvae acted synergistically via JA signaling to reduce root growth, while endophyte‐elicited GA biosynthesis suppressed the herbivore‐induced JA in roots and recovered plant growth.Our study shows for the first time the impact of a root endophyte on plant defense against below‐ground herbivores, adds to growing evidence that induced tolerance may be an important root defense, and implicates GA as a signal component of inducible plant tolerance against biotic stress.

Phosphate utilization by the fungal root endophyte Piriformospora indica

The root endophytic fungus Piriformospora indica increases plant resistance and tolerance to stress and promotes plant growth, but its ability to support plant nutrition is still controversially discussed. Irrespective of a potential nutrient transport towards the plant, the fungus might release P from sources unavailable for plant usage by transformation to available forms. To test this hypothesis, sterile solid and liquid in vitro cultures of P. indica supplied with different organic and inorganic P sources were established. Cultures were investigated for growth, solubilised P, enzyme activities, RNA accumulation of the four genes encoding phosphate transporters and the two genes for acid phosphatases and phytases respectively found in P. indica genome, and for pH values in the media. P. indica growth was higher in the presence of inorganic P than in organic P sources. Significant amounts of P were solubilised by P. indica from Ca3(PO4)2 and rock phosphate. However, no relevant intra- or extracellular enzymatic activity was detected despite RNA accumulation of related genes. In general, the genes were all repressed by higher amounts of inorganic P and were expressed the most when the fungus received phytate. We observed a decrease in medium pH in the presence of P. indica irrespective of the P source. P. indica is able to solubilise phosphate from inorganic, but not from organic P sources. This P solubilisation is not due to enzymatic activities but rather to the lowering of the medium pH.

Use of Piriformospora indica as Potential Biological Hardening Agent for Endangered Micropropagated Picrorhiza kurroa Royel ex Benth

The rich plant biodiversity of Himalayan region is vanishing at an alarming rate due to urbanization and indiscriminate collection of important plants at a large scale from the wild for trade. Overexploitation of Picrorhiza kurroa, an alpine Himalayan medicinal plant for extraction of its active compounds has led to the reduction of its natural population. In vitro regeneration offers a noteworthy solution for the propagation of endangered medicinal plants. Successful acclimatization of in vitro plants with fungal endophyte Piriformospora indica reduces the mortality rate of in vitro plantlets due to transplantation shock. Root colonization with P. indica renders growth promotion and better adaptation of a wide range of plants. Present study focuses on the use of P. indica as a biological hardening agent for increasing the percentage survival of in vitro shoots. Survival of fungus treated biohardened in vitro plants was increased by 1.3 folds. Root number in 4 weeks old P. indica treated biohardened in vitro plants enhanced by 1.25 fold and facilitated its establishment under greenhouse conditions.

High REDOX RESPONSIVE TRANSCRIPTION FACTOR1 Levels Result in Accumulation of Reactive Oxygen Species in Arabidopsis thaliana Shoots and Roots

Redox Responsive Transcription Factor1 (RRTF1) in Arabidopsis is rapidly and transiently upregulated by H2O2, as well as biotic- and abiotic-induced redox signals. RRTF1 is highly conserved in angiosperms, but its physiological role remains elusive. Here we show that inactivation of RRTF1 restricts and overexpression promotes reactive oxygen species (ROS) accumulation in response to stress. Transgenic lines overexpressing RRTF1 are impaired in root and shoot development, light sensitive, and susceptible to Alternaria brassicae infection. These symptoms are diminished by the beneficial root endophyte Piriformospora indica, which reduces ROS accumulation locally in roots and systemically in shoots, and by antioxidants and ROS inhibitors that scavenge ROS. More than 800 genes were detected in mature leaves and seedlings of transgenic lines overexpressing RRTF1; ∼40% of them have stress-, redox-, ROS-regulated-, ROS-scavenging-, defense-, cell death- and senescence-related functions. Bioinformatic analyses and in vitro DNA binding assays demonstrate that RRTF1 binds to GCC-box-like sequences in the promoter of RRTF1-responsive genes. Upregulation of RRTF1 by stress stimuli and H2O2 requires WRKY18/40/60. RRTF1 is co-regulated with the phylogenetically related RAP2.6, which contains a GCC-box-like sequence in its promoter, but transgenic lines overexpressing RAP2.6 do not accumulate higher ROS levels. RRTF1 also stimulates systemic ROS accumulation in distal non-stressed leaves. We conclude that the elevated levels of the highly conserved RRTF1 induce ROS accumulation in response to ROS and ROS-producing abiotic and biotic stress signals.

Development of carrier-based formulation of root endophyte Piriformospora indica and its evaluation on Phaseolus vulgaris L.

Endophytic fungi are plant beneficial rhizospheric microorganisms often applied as bioinoculants for enhanced and disease-free crop production. The objectives of the present work were to develop a carrier-based formulation of root endophyte Piriformospora indica as a bioinoculant. Powder formulation of four different carrier materials viz., talcum powder, clay, sawdust and bioboost (organic supplement) were evaluated and a talc-based formulation was optimized for a longer shelf life with respect to microbial concentration, storage temperature and biological activity. Finally the effect of optimized talc formulation on plant productivity was determined. The application dosages were optimized by studies on plant growth parameters of Phaseolus vulgaris L. plants under green house conditions. Five percent formulation (w/w) of talcum powder was observed to be the most stable at 30 °C with 10(8) CFU g(-1) and effective for a storage period of 6 months. The application of this optimized formulation resulted in increase of growth parameters of P. vulgaris L. and better adaptation of plants under green house conditions.

Yield increase induced by the fungal root endophyte Piriformospora indica in barley grown at low temperature is nutrient limited

The fungal root endophytes Chaetomium globosum, Epicoccum nigrum and Piriformospora indica have value as biocontrol and biofertilising organisms in barley, but have not been well tested at low temperatures. This study assessed the efficacy of the endophytes on barley varieties grown under low temperature stress with variable nutrient input. Seed from three cultivars of spring barley were inoculated with one of the three fungal root endophyte isolates – C. globosum, E. nigrum or P. indica - and grown in low temperature under higher and lower nutrient input regimes. Compared with the control, for P.indica-inoculated plants with the higher nutrient input, flowering was earlier and grain dry weight significantly greater for all barley varieties by a mean of 22 %. The nitrogen and carbon content of the grains did not differ significantly between treatments. Chaetomium globosum and Epicoccum nigrum conferred no significant benefits under either nutrient regime. Piriformospora indica is amenable to axenic culture, sporulates readily and can be multiplied rapidly, suggesting that it could be developed as an effective crop treatment in low temperature stressed barley and may have the potential to increase crop yield in colder growing conditions provided that adequate nutrients are supplied.