Wheat grain discoloration, a worldwide disease that lowers grain quality and decreases grain yield, does not have a single etiology. It has been proposed that it is a consequence of an abiotic mechanism, a response to environmental conditions or enzymatic activity. It has also been suggest that it is a biotic mechanism, a fungal infection principally by Alternaria spp. and Bipolaris sorokiniana. The present work was carried out to analyze the possible etiology of this disease in nine durum wheat genotypes from two localities of southern Buenos Aires province (Argentina) on two sowing dates. Incidence (percentage of grain discoloration) was recorded and mycobiota associated with this pathology was registered following ISTA rules. Peroxidase activity in an extract obtained from grains belonging to genotypes of the locality that showed the highest incidence was measured.
The incidence among genotypes, localities and sowing dates varied, although the genotypes with the higher and lower values of incidence were the same for all the variables tested. The fungus Alternaria spp. was isolated the most frequently followed by Fusarium spp., while Bipolaris sorokiniana was found the least frequently. Peroxidase activity showed that all the treatments had similar levels of enzymatic activity, but there was no clear differentiation between controls either between genotypes with the lowest or the highest incidence values. This suggests that peroxidase activity did not have a clear relationship with grain discoloration. In this research, it is presumed that fungal infection is the main cause of this disease.
The development of in vitro embryo production (IVEP) techniques in Felis catus is a fitting model with potential application to the conservation of endangered felid species. To improve the quality of IVEP techniques an appropriate balance of pro- and antioxidants should be provided. Under in vitro conditions, high levels of superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) mRNA provide a defence mechanism against oxidative stress for embryos. In order to improve the development of cat oocytes, the effects of SOD and CAT supplemented to in vitro maturation (IVM) medium and of GPx supplemented to in vitro fertilization (IVF) medium on development and embryo production in vitro were evaluated. Data showed an increase of 70 and 77 % of cleaved embryo and blastocyst formation, respectively, in the experiment with SOD and CAT addition to IVM medium; in the experiment with GPx addition to IVF medium the number of cleaved embryos doubled and the number of embryos increased by 96 %. Therefore, our results were positive and encourage us to continue studies on cat oocytes evaluating the effects of various dosages and combination of antioxidants.
Phylloplane microbes have been studied as strategic tools in management against plant pathogens. Non-pathogenic bacteria and fungi have been applied as crop protectants against various plant diseases. The present study aimed at evaluating the potentiality of Aspergillus niger spores in altering the activity of four key enzymes related to defense in tomato. The experiment was designed such that two groups of 50 tomato plants were considered: group 1 – sprayed with autoclaved distilled water (control) and group 2 – sprayed with A. niger spores. Spraying was carried out under aseptic conditions. The experimental parameters included analysis of the activity of peroxidase (POX), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL) and tyrosine ammonia lyase (TAL) as well as expression of POX and PPO isoforms. The results demonstrated an inductive effect of A. niger on the activity of POX, PPO, PAL and TAL. Enhanced expression of POX and PPO isoforms was also observed. The results indicated that A. niger can be considered probiotic for the management of tomato against its phytopathogens.
A representative group of hydrophilic fungi from the genus Trichoderma isolated from lignocellulose composts with varying degrees of maturity was analyzed for their ability to biodegrade a harmful anthraquinone dye, i.e. Remazol Brilliant Blue R (RBBR). In RBBR-containing post-culture liquids, there were determined the degree of RBBR decolorization, horseradish peroxidase-like, superoxide dismutase-like, and xylanase activities, and the concentrations of low-molecular phenolic compounds. The study results demonstrated that Trichoderma asperellum, T. harzianum, and T. lixii strains isolated from compost containing larger amounts of easily available lignocellulose fractions, i.e. grasses, exhibit higher RBBR decolorization effi ciency ranging from 0.3 to 62% than T. citrinoviride strains isolated from compost II, which contained greater quantities of hardly degradable lignocellulose. The decolorization of remazol blue R by the investigated Trichoderma strains intensified signifi cantly with the increase in peroxidase activity and it was correlated with a decline in the content of low-molecular phenolic compounds. The dynamics of changes in the horseradish peroxidase-like, superoxide dismutase, and xylanase activities in the aqueous post-culture liquids of the investigated fungal strains depended largely on the duration of the culture. Given their ability to adapt to water environments, e.g. wastewater, and to decolorize and detoxify the RBBR anthraquinone dye, Trichoderma fungi can be used for bioremediation of such environments.