Secondary metabolite induced tolerance to Fusarium oxysporum f.sp. cubense TR4 in banana cv. Grand Naine through in vitro bio-immunization: a prospective research translation from induction to field tolerance

An innovative tissue culture mediated incorporation of metabolite-based biomolecule (Bio-immune) at in vitro stage itself in banana cv. Grand Naine was developed and validated for the production of Fusarium oxysporum f.sp. cubense TR4 tolerant plantlets. The novel bio-immune formulation developed by us, exhibited a significant antifungal potency against Foc TR4 with a high percent inhibition (100%) at a 2.5% concentration of bio-immune on the 5th, 7th, and 9th DAI. Bio-immune integrated during in vitro shoot proliferation stage in banana cv. Grand Naine recorded significant enhancement in the growth of roots and shoots. Bio-immune (0.5%) fortified media produced 12.67 shoots per clump whereas control registered only 9.67 shoots per clump. Similarly, maximum root numbers (7.67) were observed in bio-immune plants which were significantly higher over control (5.0). The bio-immunized banana transplants recorded a higher survival rate (97.57%) during acclimatization as compared to the control (94.53%). Furthermore, evaluation of the bio-immunized plants in pot experiments revealed that unimmunized plants treated with FocTR4 (TF) exhibited mortality between 60 and 90 days. On the 90th day after planting, a high mean disease severity index (DSI) of 3.45 was observed with unimmunized plantlets while the bio-immunized plants (TFBI) and ICAR-FUSICONT treated plants (TFTR) showed substantially reduced DSI (0.20 and 1.00) compared to FocTR4 treated control (TF). Significant increases in polyphenol oxidase (PPO), peroxidase (POD), β-1,3-glucanase, phenylalanine ammonia-lyase (PAL), chitinase activities, and enhanced phenol contents were recorded in bio-immunized plants compared to unimmunized plants. Field experiments at two different locations in Bihar, India revealed that bunch weight, no. of hands/bunch, and no. of fingers/hand of bio-immune treated plants were significantly higher compared to the control

Structure-Based Engineering of Internal Cavities in Coiled-Coil Peptides

Cavities and clefts are frequently important sites of interaction between natural enzymes or receptors with their corresponding substrate or ligand molecules and exemplify the types of molecular surfaces that would facilitate engineering artificial catalysts and receptors. Even so, structural characterizations of designed cavities are rare. To address this issue, we performed a systematic study of the structural effects of single amino acid substitutions within the hydrophobic cores of tetrameric coiled-coil peptides. Peptides containing single glycine, serine, alanine, or threonine amino acid substitutions at the buried L9, L16, L23, and I26 hydrophobic core positions of a GCN4-based sequence were synthesized and studied by solution-phase and crystallographic techniques. All peptides adopt the expected tetrameric state and contain tunnels or internal cavities ranging in size from 80 Å(3) to 370 Å(3). Two closely-related sequences containing an L16G substitution, one of which adopts an antiparallel configuration and one of which adopts a parallel configuration, illustrate that cavities of different volumes and shapes can be engineered from identical core substitutions. Finally, we demonstrate that two of the peptides (L9G and L9A) bind the small molecule iodobenzene when present during crystallization, leaving the general peptide quaternary structure intact but altering the local peptide conformation and certain superhelical parameters. These high-resolution descriptions of varied molecular surfaces within solvent-occluded internal cavities illustrate the breadth of design space available in even closely-related peptides and offer valuable models for the engineering of de novo helical proteins