A physiological and molecular study of the effects of nickel deficiency and phenylphosphorodiamidate (PPD) application on urea metabolism in oilseed rape (Brassica napus L.)

Autores: Arkoun, M.; Jannin, L.; Laîné, P.; Etienne, P.; Masclaux-Daubresse, C.; Citerne, S.; Garnica Ochoa, María; García-Mina Freire, José María; Yvin, J. C.; Ourry, A. (Autor de correspondencia)
Título de la revista: PLANT AND SOIL
ISSN: 0032-079X
Volumen: 362
Número: 1 - 2
Páginas: 79 - 92
Fecha de publicación: 2013
Background and aims: Urea is the major nitrogen (N) form supplied as fertilizer in agriculture. However, urease, a nickel-dependent enzyme, allows plants to use external or internally generated urea as a nitrogen source. Since a urease inhibitor is frequently applied in conjunction with urea fertilizer, the N-metabolism of plants may be affected. The aim of this study was to determine physiological and molecular effects of nickel deficiency and a urease inhibitor on urea uptake and assimilation in oilseed rape. Methods: Plants were grown on hydroponic solution with urea as the sole N source under three treatments: plants treated with nickel (+Ni) as a control, without nickel (¿Ni) and with nickel and phenylphosphorodiamidate (+Ni+PPD). Urea transport and assimilation were investigated. Results: The results show that Ni-deficiency or PPD supply led to reduced growth and reduced 15N-uptake from urea. This effect was more pronounced in PPD-treated plants, which accumulated high amounts of urea and ammonium. Thus, Ni-deficiency or addition of PPD, limit the availability of N and decreased shoot and root amino acid content. The up-regulation of BnDUR3 in roots indicated that this gene is a component of the stress response to nitrogen-deficiency. A general decline of glutamine synthetase (GS) activity and activation of glutamate dehydrogenase (GDH) and increases in its expression level were observed in control plants.