Data/hora: 12/06/2024 01:31:59

Provedor de dados: | 61
País: | Brazil
Título: | Differential capacity of nitrogen assimilation between apical and basal leaf portions of a tank epiphytic bromeliad
Autores: | Takahashi,Cassia A.; Ceccantini,Gregório C.T.; Mercier,Helenice.
Data: | 2007-06-01
Ano: | 2007
Palavras-chave: | Bromeliaceae; Glutamate dehydrogenase; Glutamine synthetase; Stomata; Trichome; Urea.
Resumo: | The leaf is the main organ of the vegetative body of tank epiphytic bromeliads, which may be subdivided into apical and basal parts. Little is known about the existence of morphological, anatomical or physiological differences between these two leaf portions. The objective of this study was to verify the existence of a differential capacity to assimilate nitrogen from urea between basal and apical leaf portions of Vriesea gigantea, a tank epiphytic bromeliad. Plants were cultivated in vitro in the presence of 5 mM urea for 15 days. During this period, the activities of the enzymes glutamine synthetase (GS, EC 6.3.1.2) and NADH-dependent glutamate dehydrogenase (NADH-GDH, EC 1.4.1.2) were quantified, as well as the densities of trichomes and stomata found at the leaf surface of both regions. The highest activities of GS and NADH-GDH were always detected at the top portion, and on the 3rd day of in vitro cultivation an increase in these activities was detected. An inverse correlation between number of trichomes and stomata in these two leaf portions was verified: the top region presented 30% less trichomes and twice as many stomata as the basal region. This suggests that the upper region of the leaf may be preferentially involved with the assimilation of nitrogen from urea via GS and NADH-GDH, whereas the basal region may be involved with its absorption. This is the first study to report that ammonium assimilation may take place preferentially in a specific portion of tank-forming bromeliad leaves.
Tipo: | Info:eu-repo/semantics/article
Idioma: | Inglês
Identificador: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1677-04202007000200004
Editor: | Brazilian Journal of Plant Physiology
Relação: | 10.1590/S1677-04202007000200004
Formato: | text/html
Fonte: | Brazilian Journal of Plant Physiology  v.19 n.2 2007
Fonte: | info:eu-repo/semantics/openAccess