Root-Knot Disease Suppression in Eggplant Based on Three Growth Ages of Ganoderma lucidum.

This investigation presents a novel finding showing the effect of culture filtrates (CFs) of macrofungi, Ganoderma lucidum, against Meloidogyne incognita evaluated in vitro and in planta. To determine the nematicidal activity, juveniles of M. incognita were exposed to Ganoderma CFs of three different ages (Two, four and eight weeks old) of pileus and stipe at different concentrations, i.e., 100%, 50%, 10% and 1% for different time intervals (12, 24, 48 and 72 h). Ganoderma species were examined morphologically based on external appearance and analytically using SEM. The ethanolic samples of basidiocarp were prepared and analyzed for in vitro nematicidal assay and different bioactive compounds. The in vitro experiment results revealed that among all three ages of pileus and stipe, two-week-old pileus and stipe exhibited great nematotoxic potency and caused 83.8% and 73.8% juveniles' mortality at 100% concentration after 72 h of exposure time, respectively. Similarly, the two-week-old pileus and stipe showed the highest egg hatching inhibition of 89.2% and 81.0% at the 100% concentration after five days. The eight-week-old pileus and stipe were not more effective than the two- and four-week-old pileus and stipe. The metabolites were characterized using GC-MS, including sugar alcohol, steroids, silanes, glucosides, pyrones, ester, oleic acid, phthalic acid, linoleic acid, palmitates and ketones. The in planta study conducted in the greenhouse demonstrated that the root dip treatment for 30 min with Ganoderma CFs curtailed the infection level of M. incognita and promoted the eggplant plant growth. The maximum percent increase in plant length, plant fresh weight, plant dry weight, total chlorophyll, carotenoids and yield/plant was obtained at 100% conc. of fungus CFs, whereas a reduction was observed in nematode infestation parameters. It was concluded from the study that Ganoderma CFs can be explored as an effective and eco-friendly antinemic biocontrol agent in fields infected with root-knot nematodes.

Fungal P450 monooxygenases - the diversity in catalysis and their promising roles in biocontrol activity.

The fungal P450s catalyze vital monooxygenation reactions in primary and secondary metabolism, which may lead to the production of diverse secondary metabolites. Many of these, such as from the family of trichothecenes, involve in biocontrol activities. The diversified nature of fungal P450 monooxygenases makes their host organisms adoptable to various ecological niches. The available genome data analysis provided an insight into the activity and mechanisms of the fungal P450s. However, still more structural and functional studies are needed to elucidate the details of its catalytic mechanism, and the advance studies are also required to decipher further about their dynamic role in various aspects of trichothecene oxygenations. This mini review will provide updated information on different fungal P450 monooxygenases, their genetic diversity, and their role in catalyzing various biochemical reactions leading to the production of plant growth promoting secondary metabolites.

Augmentation of cytochrome P450 monooxygenase catalysis on its interaction with NADPH-cytochrome P450 reductase FMN domain from Trichoderma brevicompactum.

Cytochrome P450s are involved in a variety of monooxygenation reactions that require electron transfer from one redox partner to the other. We have recently shown the catalytic mechanism of a cytochrome P450 monooxygenase like protein (encoded by tri11 gene) that catalyzes the hydroxylation of 12,13-epoxytrichothec-9-ene (EPT) to produce trichodermol in the trichothecene biosynthetic pathway of trichodermin and harzianum A in Trichoderma brevicompactum [J Biol Inorg Chem. 22(8):1197-1209. doi: https://doi.org/10.1007/s00775-017-1496-6]. In the present work we have analyzed the effects of interaction of CPR FMN domain, a redox partner of tri11 protein, on its catalysis. The analysis of protein-protein complex interface showed various important contacts between the two protein partners that may aid in the process of electron transfer. The redox partner binding with tri11 protein on proximal side elicited catalytically important changes on the oppositely situated distal side that may help in stabilizing the active site and may play positive roles during the catalysis.

Catalytic diversity and homotropic allostery of two Cytochrome P450 monooxygenase like proteins from Trichoderma brevicompactum.

Trichothecenes are the secondary metabolites produced by Trichoderma spp. Some of these molecules have been reported for their ability to stimulate plant growth by suppressing plant diseases and hence enabling Trichoderma spp. to be efficiently used as biocontrol agents in modern agriculture. Many of the proteins involved in the trichothecenes biosynthetic pathway in Trichoderma spp. are encoded by the genes present in the tri cluster. Tri4 protein catalyzes three consecutive oxygenation reaction steps during biosynthesis of isotrichodiol in the trichothecenes biosynthetic pathway, while tri11 protein catalyzes the C4 hydroxylation of 12, 13-epoxytrichothec-9-ene to produce trichodermol. In the present study, we have homology modelled the three-dimensional structures of tri4 and tri11 proteins. Furthermore, molecular dynamics simulations were carried out to elucidate the mechanism of their action. Both tri4 and tri11 encode for cytochrome P450 monooxygenase like proteins. These data also revealed effector-induced allosteric changes on substrate binding at an alternative binding site and showed potential homotropic negative cooperativity. These analyses also showed that their catalytic mechanism relies on protein-ligand and protein-heme interactions controlled by hydrophobic and hydrogen-bonding interactions which orient the complex in optimal conformation within the active sites.