Bacterial wilt disease of tomato (Solanum lycopersicum L.), incited by Ralstonia solanacearum (Smith), is a serious agricultural problem in India. In this investigation, chemical mutagenic agents (NTG and HNO₂ treatment) and ultraviolet (UV) irradiation have been used to enhance the antagonistic property of Bacillus amyloliquefaciens DSBA-11 against R. solanacearum UTT-25 towards an effective management of tomato wilt disease. The investigation established the fact that maximum inhibition to R. solanacearum UTT-25 was exerted by the derivative strain MHNO₂-20 treated with nitrous acid (HNO₂) and then by the derivative strain MNTG-21 treated with NTG. The exertion was significantly higher than that of the parent B. amyloliquefaciens DSBA-11. These two potential derivatives viz. MNTG-21, MHNO₂-20 along with MUV-19, and a wild derivative strain of B. amyloliquefaciens i.e.,DSBA-11 were selected for GC/MS analysis. Through this analysis 18 major compounds were detected. Among the compounds thus detected, the compound 3-isobutyl hexahydropyrrolo (1,2), pyrazine-1,4-dione (4.67%) was at maximum proportion in the variant MHNO₂-20 at higher retention time (RT) of 43.19 s. Bio-efficacy assessment observed a record of minimum intensity (9.28%) in wilt disease and the highest bio-control (88.75%) in derivative strain MHNO₂-20-treated plants after 30 days of inoculation. The derivative strain MHNO₂-20, developed by treating B. amyloliquefaciens with nitrous acid (HNO₂), was therefore found to have a higher bio-efficacy to control bacterial wilt disease of tomato under glasshouse conditions than a wild-type strain.

Bacillus spp. has the potential to control bacterial and fungal diseases of crops. In vitro study, Bacillus amyloliquefaciens DSBA-11 showed best to inhibit the growth of Ralstonia pseudosolanacearum as compared to Bacillus cereus JHTBS-7, B. pumilus MTCC-7092, B. subtilis DTBS-5 and B. licheniformis DTBL-6.Three primers sets from nucleotide sequences of polyketide antibiotic synthase genes viz., macrolactin, difficidin and bacillaene of B. amyloliquefaciens FZB42 were designed and standardized protocol for simultaneous detection of polyketide antibiotics-producing strains of Bacillus spp. by multiplex—PCR with products size of 792 bp, 705 bp and 616 bp respectively. All the strains of B. amyloliquefaciens contained three polyketide antibiotic synthase genes, and B. subtilis possessed difficidin and macrolactin, whereas B. cereus JHTBS-7, B. pumilus MTCC-7092 and B. licheniformis DTBL-6 did not contain any polyketide antibiotic genes. By using this technique, polyketide-producing strains of Bacillus spp. were screened within a short period with high accuracy. These polyketide synthase genes were cloned by using a T&A vector to study the role of these genes in producing antibiotics that suppressed the growth of R. pseudosolanacearum under both in vitro and in vivo conditions. Bio-efficacy of cloned products of these genes macrolactin, bacillaene, and difficidin along with parent strain B. amyloliquefaciens DSBA-11 inhibited the growth of R. pseudosolanacearum and formed 1.9 cm², 1.9 cm², 1.7 cm² and 3.3 cm² inhibition area under in vitro conditions respectively. Minimum bacterial wilt disease intensity (29.3%) with the highest biocontrol efficacy (57.72%) was found in tomato cv. Pusa Ruby (susceptible to wilt disease) was treated with B. amyloliquefaciens DSBA-11 followed by cloned products of difficidin and macrolactin under glasshouse conditions. Hence, the developed multiplex protocol might be helpful for screening polyketide antibiotics producing potential strains of Bacillus spp. from soil which can apply for managing the wilt disease of tomatoes. The polyketide antibiotics produced by bacteria might have a significant role suppression of R. pseudosolanacearum due to the disintegration of cells.

Phytophthora is a long-established, well-known, and globally important genus of plant pathogens. Phylogenetic evidence has shown that the biologically distinct, obligate biotrophic downy mildews evolved from Phytophthora at least twice. Because, cladistically, this renders Phytophthora “paraphyletic,” it has been proposed that Phytophthora evolutionary clades be split into multiple genera ( Crous et al. 2021 ; Runge et al. 2011 ; Thines 2023 , 2024 ). In this letter, we review arguments for the retention of the generic name Phytophthora with a broad circumscription made by Brasier et al. (2022) and by many delegates at an open workshop organized by The American Phytopathological Society. We present our well-considered responses to the genus splitting proposals, both in general terms and in terms of the specific proposals for new genera, alongside new information regarding the biological properties and mode of origin of the Phytophthora clades. We consider that the proposals are mostly non-rigorous and not supported by the scientific evidence. Further, given (i) the apparent lack of any distinguishing biological characteristics (synapomorphies) between the Phytophthora clades; (ii) the fundamental monophyly of Phytophthora in the original Haeckelian sense ( Haeckel 1877 ); (iii) the fact that paraphyly is not a justification for taxonomic splitting; and (iv) the considerable likely damage to effective scientific communication and disease management from an unnecessary breakup of the genus, we report that workshop delegates voted unanimously in favor of preserving the current generic concept and for seeking endorsement of this view by a working group of the International Commission on the Taxonomy of Fungi. [ ] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .