The goal of the present research was to ascertain the potential root endophytic fungi against Dematophora necatrix, Hartig, the causal pathogen of white root rot in apples; however, it has an expanded range of hosts across different fruit trees. Out of 36 endophytic fungi segregated from symptomless roots of apple, wheat, maize, marigold, cherry, and garlic plants, only 9 isolates showed inhibitory effect during preliminary screening and were further assayed under in vitro, pot, and field conditions against the white root rot pathogen/disease. Under in vitro conditions, maximum mycelial inhibition of 81.48% was obtained with the isolate Aspergillus aculeatus strain C2. Microscopic studies on interaction between fungal endophyte with hyphal tips of D. necatrix revealed various morphological abnormalities in the hyphae. In glasshouse conditions, seed treatment pursued by soil application with Crinipellis tabtim strain M8 isolate was highly effective and exhibited 93.55% disease control. Similarly, under field conditions, the overall maximum disease control was exhibited by Crinipellis tabtim strain M8 (84.95%). The most promising root endophytes that were identified rely on morphological and ITS sequence analysis. Root colonization assay was performed which revealed maximum endosphere and rhizosphere colonization with Crinipellis tabtim strain M8. Additionally, confocal microscopic illustrations of transverse sections of root cells tenanted by fungal endophytes as compared to untreated control suggested the persistence and establishment of endophytes in the endosphere of apple seedlings. These findings present the first report on colonization of apple roots by fungal root endophytes suggesting an alternative and sustainable approach for management of white root rot disease.
The endophytic study was undertaken during 2019–2020 at department of plant pathology, Dr, YS Parmar UHF, Nauni, Solan (HP), India against Xanthomonas axonopodis pv. punicae inciting bacterial blight of pomegranate. Endophytes which we used, either endophytic bacteria or fungi have been isolated from four different genotypes/cultivars (Wild pomegranate, Kandhari, G-137 and Sindhuri) of pomegranate to study the isolation procedure and characterization of the endophytic microbes that colonize pomegranate plants. The huge diversity among the endophytic microbes and the host plants hinders a uniform protocol for isolation of endophytes and the establishment of inciting agent of bacterial blight. The most common technique that is currently used involves a thorough surface sterilization followed by fragmentation of the plant tissue and dilutions, culture of the fragments onto agar plates for endophytic bacteria and fragmentation of leaf bits after thorough surface sterilization onto agar plate for endophytic fungi. Among 27 and 19 bacterial and fungal endophytes, three potential microbes of each were selected after in vitro assay against Xanthomonas axonopodis pv. punicae which causes bacterial blight disease, and were identified based on morphological, biochemical, and cultural characteristics, respectively. This is the first report of endophytic microbes from the leaves of Punica granatum genotypes/cultivars in Himachal Pradesh, India. Future studies will determine the potential application of these isolates in biological control, growth promotion, enzyme production and colonization in host for induction of defense mechanism against bacterial blight disease of pomegranate.
Papaya plant is severely affected by different viruses among them papaya ring spot virus is causing considerable yield loss leading to the complete failure of fruiting. Therefore, present investigation commenced with molecular diagnosis, current status and temporal incidence of disease. Various symptomatic plants gave positive amplification in one step RT-PCR with both Potyvirus and PRSV CP gene specific primers indicating an amplicon of ~330bp and 850bp bands, respectively. In leaf samples, 46 to 89 per cent RNA was found positive for PRSV infection. Whereas least infection of 13 per cent was found in seeds collected from infected fruits. The disease was observed at three different experimental plots which ranges from 49 to 75.3 per cent incidence. A rapid increase in the aphid population was noticed from middle of December to February. Further, maximum aphid population was noticed at experimental plot-1 (plant pathology) followed by plot-3 (IFS) with 5.48 and 5.14/plant. Periodic observation of the disease was assessed. The appearance of ringspot was noticed in first week of October with diverse symptom. It slowly increased upto middle of January and exponentially increased upto middle of May month with 65.3 per cent incidence. The peak aphid population was noticed in middle of February (20.5/plant) which was gradually declined upto 3.9/plant in May. The present information will helpful in understanding the epidemiology of ring spot disease and suitable management possibilities.
In the present context of agriculture, which depends on hazardous chemicals to meet the growing need of presently increasing population and as a result, the conditions of soil as well as the environment is diminishing day by day. The only alternative of these problems is to utilize the natural resources i.e. biocontrol agents to combat with various types of biotic as well as abiotic factors. In the present study, Trichoderma viride was used as a biocontrol agent against Sclerotium rolfsii in cowpea plant. The germination percentage, plant height, number of stem, number of leaves, phenol (OD) and fresh weight was found maximum in cowpea plants which were soil and seed treated with biocontrol agent. Disease Incidence was also found minimum in the plants treated with maximum amount of biocontrol agent. These biocontrol agents are proving a better substitute to harmful agrochemicals and should be used as well as explored in a large fashion for better production of crops in a sustainable manner, which alongside insurance against pests and diseases are reliable for small farmers.
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