INVESTIGADORES
DESIMONE Marcelo
congresos y reuniones científicas
Título:
Ureide synthesis, accumulation and transport in Arabidopsis plants under salt and osmotic stress
Autor/es:
LESCANO, CARLOS IGNACIO; MARTINI, CAROLINA; TESSI, TOMÁS MARÍA; GONZALEZ, CLAUDIO ALEJANDRO; DESIMONE MARCELO
Reunión:
Simposio; Second International Symposium on the Nitrogen Nutrition of Plants; 2013
Resumen:
The
ureides allantoin and allantoic acid play a central role in nitrogen
transport in nodulating tropical legumes. However, the complete enzyme
set for ureide synthesis and a family of ureide permeases are widely
distributed in the plant kingdom suggesting their participation in
physiological processes not properly characterized yet. In Arabidopsis,
microarrays studies showed an upregulation of ureides synthesis genes
(xanthine dehydrogenase, uricase) during abiotic stresses. On the
contrary, allantoinase gene expression is strongly reduced after stress
suggesting that allantoin may accumulate in the cells.
We
observed accumulation of allantoin in Arabidopsis plants under osmotic
and salt stresses. This effect was exacerbated in plants grown with
ammonium as nitrogen source and suppressed in the presence of sucrose as
carbon source. The analysis of two independent T-DNA insertion lines,
causing knockout of allantoinase (alla-1 and alla-2) showed
constitutively elevated concentrations of allantoin, but a noticeable
morphological phenotype remained elusive. To determine the
physiological relevance of allantoinase gene repression on resistance
to stress, transgenic lines were generated on the genotype alla-1,
in which the coding sequence of allantoinase was introduced under the
control of the stress inducible promoter RD29A. As expected, alla-1 pRD29A::Aln
plants were not able to accumulate allantoin under stress conditions.
The phenotype of KO and RD29A:ALN plants was analysed under salt and
osmotic stress conditions. In addition, the phenotype of a KO mutant of
AtUPS5 (ups5) was analysed. AtUPS5 transports allantoin, is
expressed in the root cortex and endodermis and its expression
increases during salt and osmotic stress, suggesting a rol in
long-distance transport of allantoin during stress.