Sayaji Mehetre

Natural occurrence of Gibberella fujikuroi and its potential for control of the woolly aphid Ceratovacuna lanigera (Homoptera: Aphididae) in Indian sugarcane plantations

Abstract Studies were conducted to determine the natural occurrence of entomopathogenic fungi and their potential for utilisation in biological control of the woolly aphid (Ceratovacuna lanigera Zehntner) in Indian sugarcane plantations. A fungus Gibberella fujikuroi (Sawada) Wr. (Synonym: Fusarium verticillioides (Sacc.) Nirenberg, Synonym: Fusarium moniliforme (Sheld.) emend. Snyd. and Hans.) was found to be a promising biocontrol agent. It was further characterised and its field performance was studied. Reductions of aphid populations up to 60% were observed when the fungus was applied as two sprays at a week interval in the field.

Studies on the Behavior of 14C-chlorpyrifos in a Model Rice Ecosystem

Fate of 14C-chlorpyrifos was studied in a model rice ecosystem. The level of 14C-residues in floodwater showed initially a rapid decline in first 10 days. These residues were observed till 30 days. The insecticide residues in soil did not show any appreciable build-up, thereby indicating that the residue levels of this insecticide may not be significant. Extractable residues were formed up to 10–13% of the applied 14C-activity during the period of 136 days, while the bound fraction of 14C-residues reached a maximum of 2.9% after 92 days. Algae and rice plants showed 14C-residues to the extent of only 0.01% of the applied 14C-activity. Rice grains did not show any residues at all. These results indicate that chlorpyrifos undergoes considerable degradation in rice soils and does not leave residues, which may be of environmental concern.

Trichoderma Improves Nutrient Use Efficiency in Crop Plants

Trichoderma spp. are better known as suppressor of plant diseases. Trichoderma-based formulations thus dominate the biofungicide market. Intense researches however identified many traits in Trichoderma that extends the applications beyond plant protection. Various species of Trichoderma are capable of enhancing root growth and development, imparting tolerance to abiotic stresses, and improving uptake and use efficiency of micro- and macronutrients, culminating in enhancing crop productivity. Microbe-mediated improvement of nutrient use efficiency is gaining a lot of importance in the context of gradual loss of soil fertility/productivity that has resulted from intensive agriculture. Trichoderma spp. can enhance crop productivity by virtue of both enhanced decomposition of biomass and improving uptake of inorganic fertilizers, the topics of discussion in the current review.

Comparative efficacy of thermophilic bacterium, Bacillus licheniformis (NR1005) and antagonistic fungi, Trichoderma harzianum to control Pythium aphanidermatum-induced damping off in chilli (Capsicum annuum L.)

Damping off is a very serious disease in many field crops including chilli and its biological control has gained significance in recent times due to ill effects of chemicals. The effect of thermophilic bacterium, Bacillus licheniformis was evaluated to control Pythium aphanidermatum induced damping off in chilli (Capsicum annuum L.) under laboratory as well as pot culture conditions. B. licheniformis suppressed the growth of P. aphanidermatum equally as Trichoderma harzianum under laboratory conditions by dual culture technique. B. licheniformis treatment was at par with T. harzianum when studied in pot cultures. There was 81.18% and 83.16% inhibition of disease causing P. aphanidermatum with respect to infected control pots with B. licheniformis and T. harzianum, respectively. B. licheniformis used in present study is thermophilic in nature and hence the study has relevance in the context of failure of T. harzianum at higher temperature.

Genome-wide analysis of cytochrome P450s of Trichoderma spp.: annotation and evolutionary relationships

BackgroundCytochrome P450s form an important group of enzymes involved in xenobiotics degradation and metabolism, both primary and secondary. These enzymes are also useful in industry as biotechnological tools for bioconversion and a few are reported to be involved in pathogenicity. Trichoderma spp. are widely used in industry and agriculture and are known for their biosynthetic potential of a large number of secondary metabolites. For realising the full biosynthetic potential of an organism, it is important to do a genome-wide annotation and cataloguing of these enzymes.ResultsHere, we have studied the genomes of seven species (T. asperellum, T. atroviride, T. citrinoviride, T. longibrachiatum, T. reesei , T. harzianum and T. virens) and identified a total of 477 cytochrome P450s. We present here the classification, evolution and structure as well as predicted function of these proteins. This study would pave the way for functional characterization of these groups of enzymes and will also help in realization of their full economic potential.ConclusionOur CYPome annotation and evolutionary studies of the seven Trichoderma species now provides opportunities for exploration of research-driven strategies to select Trichoderma species for various applications especially in relation to secondary metabolism and degradation of environmental pollutants.