Twelve isolates of Trichoderma (six of T. harzianum, five of T. viride, one of T. virens), which reduced variably the incidence of collar rot disease caused in peanut by Aspergillus niger Van Tieghem, were evaluated for their potential to produce lytic enzymes during in vitro antagonism. T. viride 60 inhibited highest (86.2%) growth of test fungus followed by T. harzianum 2J (80.4%) at 6 days after inoculation (DAI) on PDA media. The specific activities of chitinase, β-1,3-glucanase and protease were 11, 3.46 and 9 folds higher in T6 antagonist (T. viride 60 and A. niger interactions) followed by 8.72, 2.85 and 9 folds in T8antagonist (T. harzianum 2J and A. niger interactions), respectively, compared to the activity produced by control petri plate T13 (A. niger alone) at 6 DAI. Activity of these lytic enzymes induced in antagonists’ plates comprises the growth of Trichoderma isolates. However, cellulase and poly galacturonase were found least amount in these antagonists treatment. A significant positive correlation (p=0.01) between percentage growth inhibition of test fungus and lytic enzymes – (chitinase, β-1,3-glucanase and protease) in the culture medium of antagonist treatment established a relationship to inhibit growth of fungal pathogen by increasing the levels of these enzymes. Among the Trichoderma isolates, T. viride 60 was found best strain to be used in biological control of plant pathogen A. niger.

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Protoplast fusions are important tools in strain improvement for bringing genetic recombination and developing hybrid strains in filamentous fungi. These are the powerful techniques for engineering of microbial strains with desirable different properties. The molecular characterization of two parent's strains (Trichoderma harzianum NBAII Th 1, Trichoderma viride NBAII Tv 23) and their corresponding fusants, produced by protoplast fusion, was investigated by random amplified polymorphic DNA (RAPD), ISSR (inter-simple sequence repeats) and internal transcribed spacer (ITS) markers. Specific results for fingerprinting were obtained by the 20 primers of each RAPD and ISSR, and four primers of ITS, respectively. These markers produced different fragment patterns with varied number of bands and yielded a total of 419 distinct bands. 13.3% were considered as polymorphic bands and 86.7% were considered as monomorphic bands. For RAPD marker, the OPC-04 primer has showed the highest polymorphism, 58.3%. While in ISSR marker, the UBC-835 primer has showed the highest polymorphism, 57.2%. The dendrogram based on RAPD marker results grouped the two parent's strains and 21 fusants into two different clusters with about 97% genetic similarity. While the dendrogram based on ISSR and ITS markers results grouped the two parent's strains and 21 fusants into two different clusters with about 88% genetic similarity. Moreover, the smallest genetic distance (0.01) was estimated between fusant-10 and fusant-12; moreover, fusant-8 and fusant-20 relatively have the highest genetic distance. Our results are consistent with the conclusion that understanding the genetic variation within parent Trichoderma strains and their corresponding fusants and molecular occurrence of protoplast fusion using RAPD, ISSR and ITS markers.

Silicon's role in mediating resistance against various stresses has been a matter of focus in the past decade. Poaeceae family plants are known as high accumulators of silicon. Wheat shows rapid absorption, the optimum accumulation of silicon occurring at around 20 days. Silicon plays a role as a mechanical and a physiological barrier. It also alters the levels of osmolytes and antioxidant enzymes which are a first line of defense in the water deficit stress; also reducing the levels of oxidative stress factors such as hydrogen peroxide. But the results vary with respect to the modes of stress application and its duration. Nowadays, foliar mode of silicon application is carried out compared to the traditional soil application yielding some promising results. Further studies are needed to confirm the mechanisms governing protection which can be done with the comparison of the transcriptome analysis of the stressed plants and also microscopic studies revealing the site of deposition.

Antagonistic effect of 12 isolates of 3 Trichoderma strains (T. virens, T. viride, T. harzianum) against the collar rot disease-causing fungus A. niger, was studied in vitro. It was observed that T. viride 60 inhibited maximum (86.2%) growth of test fungus, followed by T. harzianum 2J (80.4%). The five varieties of groundnut grown in normal (T 1 ), sick -A. niger infested soil (T 2 ) and sick + Trichoderma viride 60 (seed treatment) (T 3 ) in pot culture showed significant differences in the per cent of disease incidence of collar rot, up to 15 days after sowing (DAS). The per cent of collar rot disease incidence was higher in the GG-20 (67.4%) variety, followed by moderate in GAUG-10 and GG-13 (46%), and minimum in J-11 and GG-2 (30%) in A. niger infected pot culture, at 15 days after sowing (DAS).Based on collar rot disease incidence, groundnut varieties were screened as: susceptible, moderately susceptible and tolerant. Trichoderma seed treatment (T 3 ) reduced 51.6% of the disease incidence in susceptible varieties and 58.1% in tolerant varieties, at 15 DAS, under A. niger infection (T 2 ) in pot culture study.