Resumo

GONZALEZ-SANTOS, Rosalinda; DELGADO-ALVARADO, Adriana; ZAVALETA-MANCERA, H. Araceli  e  HERRERA-CABRERA, B. Edgar. Cytokinin BAP promotes the accumulation of hexoses and increases the activity of phosphoenolpyruvate carboxylase and phosphoenolpyruvate carboxykinase during the delay of leaf senescence in wheat. Agrociencia [online]. 2009, vol.43, n.4, pp.379-391. ISSN 2521-9766.

Cytokinins reduce their concentration during leaf senescence; but spraying of the cytokinin bencylaminopurine (BAP) delays this process; this may have applications in the control of the senescence pasture, ornamental foliage and green vegetables. The objective of the present study was to investigate the effect of BAP application on primary metabolism during the leaf senescence of Triticum aestivum L. cv. Temporalera studying the photosynthetic pigments content, soluble proteins, Rubisco, carbohydrates, enzyme activity of phosphoenolpyruvate carboxylase (PEPC) and phosphoenolpyruvate carboxykinase (PEPCK), major components of plant primary metabolism. Seedlings 21 d after sowing (DAS) were sprayed with 0.1 mM BAP or water (control). After 41 DAS the leaves treated with BAP delayed their senescence; they retained 60 % of chlorophyll and 44 % of their initial total soluble proteins, especially Rubisco. In contrast, control leaves, senesced, loosing 92 % of chlorophyll and more than 90% of proteins in the same period. The BAP promoted the accumulation of hexoses. Results indicated that BAP can increase the activity of PEPC and PEPCK enzymes during senescence. It is discussed the function of these enzymes in the regulation of pH and the translocation of nitrogen compounds during the delay of leaf senescence.

Palavras-chave : Triticum aestivum L.; cytokinins; hexoses; phosphoenolpyruvate carboxykinase; PEPCK; phosphoenolpyruvate carboxylase; PEPC.

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