The FaFlbA mutant of Fusarium asiaticum is significantly increased in nivalenol production

Mycological and Genomic Characterization of Fusarium vorosii, a Potentially Pathogenic Fungus, Isolated from Field Crops and Weeds in Korea

Fusarium vorosii (Fv) is one of the least studied species of the Fusarium graminearum species complex, a major plant pathogen causing Fusarium head blight (FHB) in a variety of crops. In this study, we isolated 12 strains of Fv from cereal samples with FHB symptoms and gramineous weeds. Trichothecene genotyping of Fv strains showed that 10 strains were nivalenol (NIV) type and 2 strains were 15-acetyldeoxynivalenol (15ADON) type. Fv strains have similar mycological characteristics to Fusarium asiaticum, a major FHB pathogen of rice in Asia, however, asexual sporulation was at least 100 to 1,000 times higher in Fv. In comparison of pathogenicity, the Fv-15ADON type was more pathogenic than the NIV type in both rice and wheat, and had a similar level of pathogenicity as the F. asiaticum-NIV type. Among the 12 Fv strains, two representative ones, Fv-NIV type RN1 and Fv-15ADON type W15A1, were selected and their whole genomes were sequenced and analyzed. Complete genome sequences of two Fv strains, RN1 and W15A1, were assembled at the chromosome level with high quality compared to known Fv genomes. The genome data of the two Fv strains were compared with the reference strains already known. As a result of comparative genome analysis, it was found that they are phylogenetically related according to the trichothecene biosynthetic gene cluster, that is, toxin chemotype. Through this study, we provided important information about Fv species that can be potential pathogens in domestic crops about biological and genomic characteristics.

A nivalenol imprinted quartz crystal microbalance sensor based on sulphur-incorporating cobalt ferrite and its application to rice samples

Nivalenol as a mycotoxin pesticide is toxic to humans and animals and causes major health problems including hemorrhage, anemia, and vomiting. Thus, the need for fast and reliable analytical systems in terms of the management of health risks resulting from nivalenol exposure has increased in recent years. The aim of this study involved a novel molecularly imprinted quartz crystal microbalance sensor preparation based on sulphur-incorporating cobalt ferrite for nivalenol detection in rice samples. For this aim, cobalt ferrite and sulfur incorporated cobalt ferrite were successfully synthesized by sol-gel and calcination methods, respectively. Then, nivalenol imprinted quartz crystal microbalance chips based on cobalt ferrite and sulfur incorporated cobalt ferrite were prepared by an ultraviolet polymerization technique including N,N'-azobisisobutyronitrile as the initiator, ethylene glycol dimethacrylate as the cross-linker, methacryloylamidoglutamic acid as the monomer, and nivalenol as the analyte. After some spectroscopic, electrochemical and microscopic characterization studies, the developed sensor was applied to rice grain samples for the determination of nivalenol. The linearity of the prepared sensor was observed to be 1.0-10.0 ng L-1 and the limit of quantification and detection limit were found to be 1.0 and 0.33 ng L-1, respectively. Finally, the high selectivity, repeatability, and stability of the prepared sensor based on sulphur-incorporating cobalt ferrite and a molecularly imprinted polymer can ensure safe food consumption worldwide.

Insights into intracellular signaling network in Fusarium species

Fusarium is a large genus of filamentous fungi including numerous important plant pathogens. In addition to causing huge economic losses of crops, some Fusarium species produce a wide range of mycotoxins in cereal crops that affect human and animal health. The intracellular signaling in Fusarium plays an important role in growth, sexual and asexual developments, pathogenesis, and mycotoxin biosynthesis. In this review, we highlight the recent advances and provide insight into signal sensing and transduction in Fusarium species. G protein-coupled receptors and other conserved membrane receptors mediate recognition of environmental cues and activate complex intracellular signaling. Once activated, the cAMP-PKA and three well-conserved MAP kinase pathways activate downstream transcriptional regulatory networks. The functions of individual signaling pathways have been well characterized in a variety of Fusarium species, showing the conserved components with diverged functions. Furthermore, these signaling pathways crosstalk and coordinately regulate various fungal development and infection-related morphogenesis.

Enhancing astaxanthin yield in Phaffia rhodozyma: current trends and potential of phytohormones

Astaxanthin is an important ketocarotenoid with remarkable biological activities and high economic value. In recent times, natural astaxanthin production by microorganisms has attracted much attention particularly in pharmaceuticals, nutraceuticals, cosmetics, and food and feed industries. Though, currently, productivity is still low and has restricted scale-up application in the commercial market, microbial production of astaxanthin has enormous prospects as it is a greener alternative to the predominating chemical synthesis. Over the years, Phaffia rhodozyma has attracted immense interest particularly in the field of biovalorization and sustainable production of natural nutraceuticals as a promising source of natural astaxanthin since it is able to use agro-food waste as inexpensive nutrient source. Many research works have, thus, been devoted to improving the astaxanthin yield from this yeast. Considering that the yeast was first isolated from tree exudates, the use of phytohormones and plant growth stimulators as prospective stimulants of astaxanthin production in the yeast is promising. Besides, it has been shown in several studies that phytohormones could improve cell growth and astaxanthin production of algae. Nevertheless, this option is less explored for P. rhodozyma. The few studies that have examined the effect of phytohormones on the yeast and its astaxanthin productivity reported positive results, with phytohormones such as 6-benzylaminopurin and gibberellic acid resulting in increased expression of carotenogenesis genes. Although the evidence available is scanty, the results are promising. KEY POINTS: • Phaffia rhodozyma is a promising source of natural astaxanthin • For industrialization, astaxanthin productivity of P. rhodozyma still needs optimization • Phytohormones could potentially augment astaxanthin yield of P. rhodozyma.