Cloning and characterization of a laccase gene from Ganoderma spp. causing basal stem rot disease in coconut

Basal stem rot disease in coconut is caused by the white-rot fungus Ganoderma lucidum, which is soilborne in nature. Its degree of virulence is governed by the activity of the laccase enzyme. Of twenty-five isolates belonging to the genus Ganoderma obtained from different host species, the isolate from Silent Valley (SV) showed the greatest laccase activity in vitro, followed by the isolate from Veppankulam (CRS-1). These two isolates also reacted positively in the laccase assay in vitro. The laccase-positive SV and CRS-1 isolates were further amplified by polymerase chain reaction (PCR) using degenerate primers for the partial sequence, which showed the fragment size of 200 bp. The highly virulent SV isolate was cloned in a plasmid vector and sequenced. It was confirmed as a partial-length laccase gene and submitted to the GenBank database. The nucleotide sequence of the DNA of this isolate showed high homology with those of the laccase genes of other basidiomycetes

Effcacy of different biological control agents against major postharvest pathogens of grapes under room temperature storage conditions

Grapes were treated post harvest with a variety of biological agents to determine their effcacy in reducing yield loss. The agents Pseudomonas, Bacillus, Trichoderma and yeast isolates were individually screened against a number of postharvest pathogens including Aspergillus carbonarius, Penicillum expansum, and Fusarium moniliforme. B. subtilis strains EPC-8 and EPCO-16 showed high mycelial growth suppression of A. carbonarius and P. expansum  in vitro. The fungal antagonist Trichoderma viride strain (Tv Tvm) was the most effective, inhibiting mycelial growth by 88.8 per cent. The biological control agents were tested in pre, post and combined inoculation studies against postharvest pathogens of grapes.  In the pre inoculation, B. subtilis (EPC-8) reduced the disease incidence of A. carbonarius causing rot, T. harzianum (Th Co) was effective against P. expansum, and T. viride (Tv Tvm) was effective against F. moniliforme. The same trend of effectiveness was also found in the post-inoculation and combined inoculation tests

Complete Genome Sequence Analysis of <i>Bacillus subtilis</i> Bbv57, a Promising Biocontrol Agent against Phytopathogens

Plant growth-promoting rhizobacteria (PGPR) are a group of root-associated beneficial bacteria emerging as one of the powerful agents in sustainable plant disease management. Among the PGPR, Bacillus sp. has become a popular biocontrol agent for controlling pests and the diseases of several crops of agricultural and horticultural importance. Understanding the molecular basis of the plant growth-promoting and biocontrol abilities of Bacillus spp. will allow us to develop multifunctional microbial consortia for sustainable agriculture. In our study, we attempted to unravel the genome complexity of the potential biocontrol agent Bacillus subtilis Bbv57 (isolated from the betelvine’s rhizosphere), available at TNAU, Coimbatore. A WGS analysis generated 26 million reads, and a de novo assembly resulted in the generation of 4,302,465 bp genome of Bacillus subtilis Bbv57 containing 4363 coding sequences (CDS), of which 4281 were functionally annotated. An analysis of 16S rRNA revealed its 100% identity to Bacillus subtilis IAM 12118. A detailed data analysis identified the presence of >100 CAZymes and nine gene clusters involved in the production of secondary metabolites that exhibited antimicrobial properties. Further, Bbv57 was found to harbor 282 unique genes in comparison with 19 other Bacillus strains, requiring further exploration