Role of a maize flavonol synthase in the protection against UV-B radiation

JULIA EMILIANI; ERICH GROTEWOLD; PAULA CASATI; DRINCOVICH, MARIA FABIANA

Congreso; XXIX REUNIÓN ARGENTINA DE FISIOLOGÍA VEGETAL; 2012

Flavonoids are secondary metabolites widely distributed in higher plants, that unlike primary metabolites, are not essential for the survival of plants, but have important vital functions such as to absorb UV light, regulate the transport of the plant hormone auxin, modulate the levels of reactive oxygen species (ROS) and give color to flowers to attract pollinators. A group of them, the flavonols (quercetin and kaempferol), are synthesized from dihydroflavonols by the action of the enzyme flavonol synthase (FLS). With the aim of studying the role of these compounds in protecting against UV-B radiation, Arabidopsis thaliana plants (ecotype Col-0) were transformed with the p35S::ZmFLS1 construction, and homozygous transgenic lines over-expressing ZmFLS1 were selected. In addition, polyclonal antibodies generated against the enzyme ZmFLS1 were purified and tested by western blot analysis, demonstrating the expression of the ZmFLS1 protein in the transgenic plants. Transgenic plants show increased levels of flavonols quantified by HPLC. UV-B treatments were performed in wild type and transgenic plants, and we evaluated DNA damage accumulation by dot blot assays, showing decreased levels of pyrimidine dimers in the transgenic plants. On other hand, physiological parameters were assessed immediately finalized the UV-B treatment, such as the maximum efficiency of photosystem II and electrolyte leakage to evaluate the protection of flavonols against UV-B.