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Effects of both urea and light on the ability of accumulation and secretion of proteins and phenolics by Cladonia verticillaris

Talitha L.Vasconcelos, Roberto deArmas, Eug�?ªnia C.Pereira, Roc�?­o Santiago, Nica�?§io H.Da Silva, CarlosVicente,Mar�?­a-Estrella Legaz

The lichen Cladonia verticillaris lives on quartzarenic neosols of Pernambuco (Brazil) in which sugar cane cultures are often established and fertilized by urea. The thalli of the above mentioned lichen are experimentally maintained on different concentrations of urea in light or in darkness, conditions that simulate agricultural uses. The capture of the external urea by the thalli was higher in light than in the dark depending on the urea concentration. Urea inside the thallus is hydrolyzed by induced urease to produce both carbon dioxide and ammonia. This implies an increase of the protein production, a part of which is secreted to the media whereas another part is retained by the thallus. Both secretion and retention of proteins are increased by light. Production of lichen phenolics, protocetraric and fumarprotocetraric acids, increases in light and fumarprotocetraric acid mainly migrates to the cortex. Both production and migration are slightly effected by urea.