Aim: To understand the mechanism of necrosis incited by a host-selective phytotoxin designated as Rhizoctonia solani toxin (RST) identified to be a potential pathogenic factor of R. solani AG1 IA, causing sheath blight (ShB) of rice. Methods and Results:The metabolomic changes induced by the phytotoxic metabolite in a ShB susceptible rice cultivar were elucidated by gas chromatography-mass spectrometry analysis and compared with that of the pathogen to identify rice metabolites targeted by the phytotoxin. The profiles of about 29 metabolites with various physiological roles in rice plants have been identified worldwide. Unsupervised and supervised multivariate chemometrics (principal component analysis and partial least squares-discriminant analysis) and cluster (Heat maps) analyses were used to compare the metabolites obtained from chemical profiles of the treatments with sterile distilled water (SDW) control. The results indicated that the rice plant expressed more metabolites in response to the pathogen than the phytotoxin and was lowest in SDW control. The key metabolites expressed in rice in response to the treatments were investigated by the variable importance in projection (VIP) analysis using p < 0.05 VIP >15. The analysis identified 7 and 11 upregulating metabolites in the phytotoxin and the pathogen treatments, respectively, compared to the untreated control. Among the phytotoxin-treated and the pathogen inoculated samples, the phytotoxin-treated sample recorded upregulation of six metabolites, whereas nine metabolites were upregulated in the pathogen-inoculated samples. These upregulating metabolites are speculated for the necrotic symptoms characteristic to both the phytotoxin and pathogen. In this analysis, hexadecanoic acid and dotriacontane were highly expressed metabolites specific to the phytotoxin and pathogen-treated samples, respectively. Besides upregulation, the metabolites also have a VIP score of >1.5 and hence fulfilled the criteria of classifying them as reliable potential biomarkers. In the pathway analysis, hexadecanoic acid and dotriacontane were identified to be involved in several important biosynthetic pathways of rice, such as the biosynthesis of saturated fatty acid and unsaturated fatty acids cutin, suberin and wax. Conclusions:The study concludes that though certain metabolites induced by the phytotoxin in the susceptible variety during necrosis shares with that of the pathogen, the identification of metabolites specific to the phytotoxin in comparison to the

Cytochrome P450s (P450s) are a unique multifamily class of enzymes that possess the capability to exhibit catalytic versatility in several biochemical reactions which entails metabolite biosynthesis, primary and secondary metabolism. Fusarium spp. is an important microorganism with many members known to produce secondary metabolites that cause plant diseases and mycotoxicoses in animals and humans. In this present study, from the initially screened 4,579 proteins, we elucidated the nature of abundance, evolutionary relationships, classification and cellular location of 320 cytochrome P450 from 17 phytopathogenic members of Fusarium species. The total CYPs protein sequences were phylogenetically grouped into seventeen (17) clades. Eighty-six (86) CYPs families and forty-eight (48) clans were identified. Twenty-seven (27) families were each found in only one species. The CYPs were found to be majorly localized in the endoplasmic reticulum. The non-ribosomal peptide synthetase-like (NRPS-like) gene cluster was the predominant secondary metabolic-related gene cluster across all the seventeen selected Fusarium species except in F. cucurbiticola and F. solani, where PolyKetide Synthase (PKS) was the most prevalent. The presence of numerous families and clans as observed in in this study shows the expansions of the CYPs families across Fusarium species, this CYPs family and clan expansion is often associated with the evolvement of several fungal traits that include their pathogenicity adaptation to survive on an extensive range of toxic substrates. Identification of P450 proteins in these pathogenic fungi provides fundamental information for further basic and applied biological research into the physiological and toxigenic roles of P450s in Fusarium species.

No abstract

In the food sector, ensuring the safety of packaged food products reaching the consumers or end-users have over the years been a major concern in the industry. Several outbreaks have been reported over the years caused by foodborne pathogens or the consumption of expired products. The use of nanobiomaterials for food packaging which can monitor the freshness, toxicants and microbial contamination rate has today given the food sector a major boost in addressing not only food toxicity but also increasing the shelf-life, quality and acceptability of packaged foods. Food industries in recent times have been heavily investing in the utilization of packaging materials that are biodegradable and biocompatible with sensors to replace the initial non-degradable packaging materials such as polyethene- and polyvinylchloride-containing plastics which already have been established as having toxic effects. Biological nanoparticle-based sensors are now being used to detect fish and/or meat deterioration after packaging, heavy metals in food, nutrient level, toxins, alcohol presence and microorganisms present in food. This technology is cheap, very sensitive and provides a user-friendly on-site or online assessment of the safety of the respective packaged foods.