Biotechnology Research Centre

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    Nano-enhanced defense: Titanium-enriched Alginate–Bentonite coating augments Bacillus amyloliquefaciens D203 efficacy against Magnaporthe oryzae in Kenyan rice cultivation.
    (Heliyon, 2024-08-09) Mirara, F.; Dzidzienyo, K.D.; Mwangi, M.
    Rice blast disease, caused by Magnaporthe oryzae, poses a significant threat to global rice production, necessitating the development of effective and sustainable management strategies. Biological control using beneficial microbes like Bacillus amyloliquefaciens has emerged as a promising approach due to its ability to enhance plant resistance and reduce disease incidence. Nano-encapsulation of bacteria, which involves embedding beneficial microbes within nanomaterials, offers a novel method to improve the stability, survival, and efficacy of these biocontrol agents. This study evaluated the capacity of encapsulated Bacillus amyloliquefaciens D203, embedded within an alginate-bentonite coating infused with titanium nanoparticles (TNs), to stimulate defense responses in rice seedlings challenged by the Magnaporthe oryzae, the causal agent of rice blast disease. Encapsulation was achieved using the extrusion technique, with some modifications. Using a completely randomized design, the experiment was conducted in a greenhouse, with four treatments replicated four times. The experiment used the popular Kenyan rice variety "BASMATI 370”. The study investigated the impact of strain D203 on the incidence, severity, and area under disease progress curves related to M. oryzae, as well as the expression of defense-related enzymes. The results demonstrated that rice plants derived from seeds coated with the D203 encapsulated B. amyloliquefaciens strain exhibited higher levels of defense-related enzyme expression, including peroxidase (POD), phenylalanine ammonia-lyase (PAL), superoxide dismutase (SOD) and catalase (CAT), compared to controls. In addition, the incidence and severity of the disease were markedly lower in plants treated with encapsulated B. amyloliquefaciens compared to controls, sometimes paralleling the efficacy of hexaconazole treatment. These findings suggest that the encapsulation of strain D203 has the potential to enhance resistance against rice blast disease by inducing systemic resistance through the production of antioxidant enzymes
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    Occurrence of cassava mosaic begomovirus associated satellites on cassava in Ghan
    (Taylor & Francis Group, 2021) Torkpo, S.K.; Amponsah, E.; Arhin, C.D.; Offei, S.K.
    Cassava mosaic disease (CMD), arguably the most important viral disease of cassava, an important food security crop has in recent times, been reported to be associated with satellites in some parts of sub-Saharan Africa. We investigated the status of Cassava mosaic begomovirus and associated satellites in CMD-affected cassava plants in Ghana using polymerase chain reaction. In all, 110 CMD-affected cassava leaf samples collected from cassava fields in Southern Ghana. Africa cassava mosaic virus (ACMV) was detected in 107 (97%) cassava leaf samples, out of which 76 (69%) was in mixed infections with East Africa cassava mosaic virus-Cameroon (EACMV-CM). EACMV (CM) alone was detected in three (3%) cassava leaf samples. Out of the 110 cassava leaf samples affected by cassava mosaic begomoviruses, satIII and satII were detected in 66 (60%) and 47 (43%), respectively. To the best of our knowledge, detection of CMB-associated satellites in Ghana is the first in the country and possibly in West Africa, and has serious epidemiological implications on the management of CMD, thereby requiring further studies and concerted efforts to safeguard cassava production.
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    Novel rhizobia exhibit superior nodulation and biological nitrogen fixation even under high nitrate concentrations
    (FEMS Microbiology Ecology, 2019-12-20) Obirih-Opareh, J.; Nguyen, H.P.; Miwa, H.; Suzaki, T.; Yasuda, M.; Okazaki, S.
    Legume–rhizobium symbiosis leads to the formation of nitrogen-fixing root nodules. However, externally applied chemical nitrogen fertilizers (nitrate and ammonia) strongly inhibit nodule formation and nitrogen fixation. Here, we isolated several rhizobial strains exhibiting a superior nodulation and nitrogen fixation with soybean at high nitrate concentrations. The nodulation of soybean symbiont Bradyrhizobium diazoefficiens USDA110 was significantly inhibited at 12.5 mM nitrate; however, three isolates (NKS4, NKM2 and NKTG2) were capable of forming nitrogen-fixing nodules, even at 20 mM nitrate. These isolates exhibited higher nodulation competitiveness and induced larger nodules with higher nitrogen-fixation activity than USDA110 at 5 mM nitrate. Furthermore, these isolates induced more nodules than USDA110 even in nitrate-free conditions. These isolates had a distant lineage within the Bradyrhizobium genus; though they were relatively phylogenetically close to Bradyrhizobium japonicum, their morphological and growth characteristics were significantly different. Notably, in the presence of nitrate, expression of the soybean symbiosis-related genes (GmENOD40 and GmNIN) was significantly higher and expression of GmNIC1 that is involved in nitrate-dependent nodulation inhibition was lower in the roots inoculated with these isolates in contrast with inoculation of USDA110. These novel rhizobia serve as promising inoculants for soybeans cultivated in diverse agroecosystems, particularly on nitrate-applied soils.
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    Allelic diversity of S-RNase alleles in diploid potato species
    (Theoretical and Applied Genetics, 2016-10) Dzidzienyo, D.K.; Bryan, G.J.; Wilde, G.; Robbins, T.P.
    Key message: The S-ribonuclease sequences of 16 S-alleles derived from diploid types of Solanum are presented. A phylogenetic analysis and partial phenotypic analysis support the conclusion that these are functional S-alleles. Abstract: S-Ribonucleases (S-RNases) control the pistil specificity of the self-incompatibility (SI) response in the genus Solanum and several other members of the Solanaceae. The nucleotide sequences of S-RNases corresponding to a large number of S-alleles or S-haplotypes have been characterised. However, surprisingly, few S-RNase sequences are available for potato species. The identification of new S-alleles in diploid potato species is desirable as these stocks are important sources of traits such as biotic and abiotic resistance. S-RNase sequences are reported here from three distinct diploid types of potato: cultivated Solanum tuberosum Group Phureja, S. tuberosum Group Stenotomum, and the wild species Solanum okadae. Partial S-RNase sequences were obtained from pistil RNA by RT-PCR or 3′RACE (Rapid Amplification of cDNA Ends) using a degenerate primer. Full-length sequences were obtained for two alleles by 5′RACE. Database searches with these sequences identified 16 S-RNases in total, all of which are novel. The sequence analysis revealed all the expected features of functional S-RNases. Phylogenetic analysis with selected published S-RNase and S-like-RNase sequences from the Solanaceae revealed extensive trans-generic evolution of the S-RNases and a clear distinction from S-like-RNases. Pollination tests were used to confirm the self-incompatibility status and cross-compatibility relationships of the S. okadae accessions. All the S. okadae accessions were found to be self-incompatible as expected with crosses amongst them exhibiting both cross-compatibility and semi-compatibility consistent with the S-genotypes determined from the S-RNase sequence data. The progeny analysis of four semi-compatible crosses examined by allele-specific PCR provided further confirmation that these are functional S-RNases. © 2016, The Author(s).