In the initial phase of the project, we prepared a series of phytophthora extracts to evaluate their bioactivity and stress-protective effects. Three Phytophthora species that represent habitats from both temperate and tropical regions were used in a Soxhlet extraction to prepare different fractions. Subsequently, their impact on viral infection (Tobacco Necrotic Virus A) in Nicotiana tabacum and heat stress alleviating effect on Arabidopsis were explored. Interestingly, all of them showed similar effects and one representative extract was prioritized for further experiments. We observed a decreased viral infection on tobacco plants primed with phytophthora extracts. Arabidopsis plants leaf treated with phytophthora extract did not display any morphological changes under control conditions. Similarly, no differences were observed when the pretreated plants were exposed to heat stress. In contrast, when the phytophthora extracts were applied to the soil, this led to more pronounced heat stress-induced morphological changes. To evaluate the impact of phytophthora extracts on stress signalling pathways, we subjected prom:LUC lines carrying stress-responsive promoter sequence implicated in redox signalling and observed induction of their activation.
To assess the bioactivity of rosemary extracts, we obtained three different extractions by CO2, Soxhlet, and steam distillation. We tested their effect on Arabidopsis plants exposed to heat stress and observed a more pronounced effect of heat stress on pretreated plants.
As an alternative way to enhance plant resistance to pathogens, we explored the activity of extracts of seaweed against various pathosystems (TNVA-Nicotiana tabacum, soybean-TNVA and citrus-Xanthomonas citri). We have observed a protective effect against both viral and bacterial pathogens which is in contrast to the commercially available laminarin which protects only against bacterial pathogens.
To understand the molecular mechanisms behind the action of the commercially available product SuperFifty, we are currently exploring the activation of prom:LUC lines carrying stress-responsive promoter sequences and optimizing a method to quantify changes in histone post-translational modifications that are likely to underlie its priming effect.
