Development of PCR-based molecular marker for screening of disease-suppressive composts against Fusarium wilt of tomato (Solanum lycopersicum L.).

The present study was carried out to develop a PCR-based molecular marker suitable for screening of disease-suppressive composts against Fusarium wilt of tomato. An effective uncultured bacterial community was screened from our previous study on investigation of microbial communities in composts for their potential for biocontrol of Fusarium wilt. Based on available sequence information (Accession no. HQ388491) of selective community, PCR-based molecular markers were designed and tested for their specificity in different compost sample. To confirm specificity of designed marker, real-time reverse transcription-PCR (qRT-PCR) analysis was performed. Selective marker efficacy was further tested for different set of composts and results were cross-verified by conducting bioassay of same composts against Fusarium wilt in tomato crop. Results showed that out of two designed set of primers (i.e., PAC1F/PAC1R and PAC4F/PAC4R), primer set PAC4F/PAC4R resulted in successful amplification of 199 bp in highly disease-suppressive compost (i.e., CPP); however, no/below detection level amplification was observed in non-suppressive compost (JC). qRT-PCR analysis confirmed the specificity of selective marker by representing single peak in melting curve. A clear difference was observed in relative population of selective community in different set of composts. It was observed maximum in the most effective compost, i.e., CPP followed by other disease-suppressive composts. Cross-examination of results with bioassay confirmed that composts with presence of selective bacterial community having no/very less disease incidence of Fusarium. It is clearly evident from the study that such kind of molecular markers can be developed and used in future research focusing on compost-based disease suppression.

Repellent activity of some essential oils against two stored product beetles Callosobruchus chinensis L. and C. maculatus F. (Coleoptera: Bruchidae) with reference to Chenopodium ambrosioides L. oil for the safety of pigeon pea seeds.

Essential oils from 35 aromatic and medicinal plant species of Gorakhpur Division (U. P., India) were evaluated for their repellent activity against pulse bruchids Callosobruchus chinensis L. and C. maculatus F. of stored pigeon pea seeds. The oil concentration was at 0.36 µl/ml. Out of 35 essential oils, Adhatoda vasica Ness and Chenopodium ambrosioides L. oils showed absolute (100 %) insect repellency. Chenopodium oil exhibited 100 % mortality for both the test insects at 10 µl concentration (LD50 = 2.8 µl for C. chinensis & 2.5 µl for C. maculatus) and more toxic than Adhatoda oil (LD50 = 6.8 µl for C. chinensis & 8.4 µl for C. maculatus). During in vivo evaluation, 0.29 and 0.58 µl/ml of Chenopodium oil significantly enhanced feeding deterrence in insects and reduced the seed damage as well as weight loss of fumigated pigeon pea seeds up to 6 months of storage as compared to control set. Thus, Chenopodium oil can be used as an effective option of commercial fumigants for the storage of pigeon pea seeds against pulse bruchids.

Compost: its role, mechanism and impact on reducing soil-borne plant diseases.

Soil-borne plant pathogens are responsible for causing many crop plant diseases, resulting in significant economic losses. Compost application to agricultural fields is an excellent natural approach, which can be taken to fight against plant pathogens. The application of organic waste products is also an environmentally friendly alternative to chemical use, which unfortunately is the most common approach in agriculture today. This review analyses pioneering and recent compost research, and also the mechanisms and mode of action of compost microbial communities for reducing the activity of plant pathogens in agricultural crops. In addition, an approach for improving the quality of composts through the microbial communities already present in the compost is presented. Future agricultural practices will almost definitely require integrated research strategies to help combat plant diseases.

Evaluation of Clausena pentaphylla (Roxb.) DC oil as a fungitoxicant against storage mycoflora of pigeon pea seeds.

BACKGROUND: The present study aimed to evaluate the antifungal activity of 30 essential oils against four dominant fungi Aspergillus flavus Link., A. niger van Tieghem, A. ochraceus Wilhelm and A. terreus Thom of stored pigeon pea seeds at a concentration of 0.36 µL mL(-1). Various fungitoxic properties, such as minimum inhibitory concentration, minimum fungicidal concentration and fungitoxic spectrum, of the most potent oil were determined. The efficacy of the most potent oil in preservation of pigeon pea seeds for 6 months was also carried out by storing 1 kg of seeds in the oil vapour. RESULTS: Clausena pentaphylla and Citrus limon oils were more effective against all the fungi tested, which exhibited 100% per cent mycelial inhibition. The minimum inhibitory concentration of C. pentaphylla oil was determined as 0.07 µL mL(-1) against all the test fungi and was found to be more toxic than Citrus limon oil. C. pentaphylla oil exhibited a broad range of fungitoxicity against 16 other storage fungi of pigeon pea seeds. C. pentaphylla oil significantly protected 1 kg seeds of pigeon pea from fungal deterioration and was superior to synthetic fumigants. The oil did not show any phytotoxicity and the protein content of the seeds was significantly retained for up to 6 months of storage. CONCLUSION: Thus, C. pentaphylla oil may be used as an effective fumigant in the ecofriendly management of storage fungi of pigeon pea seeds.

Microbiological studies of ethnic meat products of the Eastern Himalayas.

Native microorganisms from some ethnic meat products of the Eastern Himalayas such as lang kargyong, yak kargyong, faak kargyong, lang satchu, yak satchu and suka ko masu were isolated and characterized. The bacterial isolates included Lactobacillus sake, Lactobacillus curvatus, Lactobacillus divergens, Lactobacillus carnis, Lactobacillus sanfrancisco, Lactobacillus plantarum, Lactobacillus casei, Lactobacillus brevis, Enterococcus faecium, Leuconostoc mesenteroides, Pediococcus pentosaceous, Bacillus subtilis, Bacillus mycoides, Bacillus thuringiensis, Bacillus lentus and Bacillus licheniformis, Micrococcus and Staphylococcus. Yeast isolates included Debaryomyces hansenii, Debaryomyces polymorphus, Debaryomyces pseudopolymorphus, Pichia burtonii, Pichia anomala, Candida famata and the mould Rhizopus was also identified. Many of the LAB isolates demonstrated some antimicrobial activity, enzymatic activity and a few showed a high degree of hydrophobicity. None of the strains produced biogenic amines.