Amine oxidases in the oxidative pathway of polyamines in Medicago truncatula grown under different nitrogen sources
Fecha
2018Autor
Versión
Acceso abierto / Sarbide irekia
Tipo
Trabajo Fin de Grado/Gradu Amaierako Lana
Impacto
|
nodoi-noplumx
|
Resumen
Crop productivity relies heavily on fertilization. However, the augmented use of
fertilizers by industrial farming results in an over-accumulation of nutrients in the soil,
which induces nutritional stresses. The utilization of nitrate, ammonium, and urea as
nitrogen sources leads to an elevated intracellular accumulation of ammonium, which
makes indispensable to understand and elucidate the ...
[++]
Crop productivity relies heavily on fertilization. However, the augmented use of
fertilizers by industrial farming results in an over-accumulation of nutrients in the soil,
which induces nutritional stresses. The utilization of nitrate, ammonium, and urea as
nitrogen sources leads to an elevated intracellular accumulation of ammonium, which
makes indispensable to understand and elucidate the mechanism by which plants face
ammonium toxicity. Early studies on plant metabolism of polyamines pointed to their
involvement in responses to different environmental stresses. However, the precise
mechanisms by which polyamines control plant responses to stress stimuli have not been
elucidated yet. Previous results of our laboratory suggested the importance of the “urea
cycle” on the tolerance of Medicago truncatula seedlings to ammonium, in which
polyamine catabolism might play a key role in such tolerance, but there are still important
gaps to fulfill. The excess of ammonium originated either from ammonium nutrition or
from polyamine metabolism may be suggested to act as a feedback inhibitor of amine
oxidases since polyamines, mainly putrescine, were accumulated while the content of γaminobutyric
acid decreased. In the present study, an intra- and interspecific phylogenetic
analyses of amine oxidases are performed in order to characterize them. Moreover, the
differential effect of distinct nitrogen nutrition and doses on diamine oxidases and
polyamine oxidases activities involved in the catabolic processes of polyamines in
connection to the “urea cycle” was assayed. In general terms, the results obtained in this
study showed higher diamine oxidase activities in Medicago truncatula plant shoots than
that observed in roots. In addition, plants supplied with low dose of ammonium exhibited
significantly higher diamine oxidase activity in shoots in comparison with nitrate- and
urea-fed plants, whereas diamine oxidase activity was significantly higher in roots of
ammonium-fed plants at high dose. Since diamine oxidase activity has been shown to be
increased under ammonium conditions in Medicago truncatula tissues, this might suggest
the importance of polyamine catabolism in the tolerance against high ammonium
conditions. Although alternative mechanisms underlying ammonium stress/tolerance
response are proposed in this report, future research should be performed to elucidate the
mechanisms underlying plant ammonium tolerance responses. [--]
Materias
Medicago truncatula,
Amine oxidases,
Polyamines,
Diamine oxidase,
Nitrogen,
Ammonium
Titulación
Graduado o Graduada en Ingeniería Agroalimentaria y del Medio Rural por la Universidad Pública de Navarra /
Nekazaritzako Elikagaien eta Landa Ingurunearen Ingeniaritzan graduatua Nafarroako Unibertsitate Publikoan