Flavonoids are systemically induced by UV-B in Zea mays.

TOSSI, V; LAMATTINA, L.; CASSIA, R.

San Miguel de Tucumán, Tucumán, Argentina

Congreso; XLV Reunion de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB); 2009

Argentina de Investigación Bioquímica y Biología Molecular (SAIB)

Flavonoid concentration is increased by UV-B irradiation, but is unknown if this is a local or systemic response. The biosynthesis of this metabolites is regulated by P1 (transcription factor) and the enzyme activity of chalcone synthase (CHS) and chalcone isomerase (CHI). Nitric oxide (NO) is involved in the UV-B response and it regulates the expression of CHS. The aim of this work was to determine if maize flavonoids are local or systemically induced by UV-B, and which is the participation of NO in this response. We have used maize seedlings where the second leaf was sprayed with H2O or cPTIO (a NO scavenger), and then completely covered (C), partially covered (P) or uncovered (U) before to be UV-B irradiated. The results show a 60% increase in the NO concentration of U, 42% in P and 35% in C respectively.Flavonoid concentration increased 90% in C, 70% in P and 40% in U. Flavonoid concentration was reduced when leaves were pretreated with cPTIO. RT-PCR shows that CHS, CHI and P1 were up-regulated by UV-B in U, P and C, but downregulated with cPTIO.We have analyzed the subcellular localization of flavonoid and NO in UV-B irradiated plants. Flavonoid localization was coincident with the NO presence in the irradiated surface of the leaves and flavonoids were detected in vesicles.These results indicate that flavonoids are systemically induced by UV-B in a NO-related mechanism.