Disruption of a putative "urea cycle" and its connection to polyamine metabolismn in plants under ammonium nutrition
Consultable a partir de
2025-03-01
Fecha
2020Autor
Versión
Acceso embargado 5 años / 5 urteko bahitura
Tipo
Trabajo Fin de Máster/Master Amaierako Lana
Impacto
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nodoi-noplumx
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Resumen
Environmental stresses are the major cause of crop loss worldwide. The augmented use
of fertilizers by industrial farming results in an over accumulation of nutrients in the soil,
which originates lixiviation and eutrophication. Ammonium nutrition represents a valid
alternative which binds tighter to the soil particles and then reduces the lixiviation.
However, ammonium as sole source of nitr ...
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Environmental stresses are the major cause of crop loss worldwide. The augmented use
of fertilizers by industrial farming results in an over accumulation of nutrients in the soil,
which originates lixiviation and eutrophication. Ammonium nutrition represents a valid
alternative which binds tighter to the soil particles and then reduces the lixiviation.
However, ammonium as sole source of nitrogen induces higher intracellular ammonium
content leading to physiological and morphological disorders, impairing the optimal growth
and development of the plants. In the present study, the disruption of the ‘urea cycle’ and
polyamine (PA) metabolism by high contents of ammonium is proposed as a key
mechanism underlying the tolerance response of Medicago truncatula to ammonium
stress. In order to elucidate the involvement of M.truncatula amine oxidases in ammonium
tolerance response, the effect of different nitrogen sources and doses on these enzymes
were studied at phylogenetic, transcriptional and enzymatic level. In addition, hydrogen
peroxide content was analysed to clarify whether it could be involved in ammonium
tolerance of M.truncatula plants. In general terms, transcript levels of genes encoding
diamine oxidases decreased in ammonium-fed seedlings in comparison to nitrate-fed
plants, as well as the enzymatic activity did. In contrast, the expression of polyamine
oxidases encoding genes did not show acute significant differences between treatments.
However, the enzymatic activity of polyamine oxidases increased in shoot tissue of high
ammonium-fed seedlings, and showed an increase tend in roots. Finally, the content of
hydrogen peroxide was higher in M.truncatula plants grown under high nitrogen nutrition,
especially in root tissue of high ammonium-fed seedlings. These results suggest the
importance of the ‘urea cycle’ and PA metabolism in the tolerance against the abiotic
stress induced by ammonium nutrition, as source of GABA and hydrogen peroxide, which
are involved in abiotic stress responses. Finally, the accumulation of polyamine-derived
hydrogen peroxide is suggested to be related to lignin deposition in plant cell walls of M.
truncatula plants grown under high nitrogen nutrition. Anyway, future research should be
performed to fully elucidate the mechanisms underlying plant ammonium tolerance
responses. [--]
Materias
Urea cycle,
Polyamine (PA),
Ammonium nutrition
Titulación
Máster Universitario en Ingeniería Agronómica por la Universidad Pública de Navarra /
Nekazaritza Ingeniaritzako Unibertsitate Masterra Nafarroako Unibertsitate Publikoan