INVESTIGADORES
GUIAMET Juan Jose
congresos y reuniones científicas
Título:
?Isoforms of glutamine synthetase during barley flag leaf senescence under field conditions?.
Autor/es:
NADIA ROLNY; LORENZA COSTA; ZSCHIESCHE W; KLAUS HUMBECK; JUAN JOSÉ GUIAMET
Lugar:
Potrero de lo Funes, San Luis
Reunión:
Congreso; SAIB, th 47 Annual Meeting Argentine Society for Biochemistry and Molecular Biology-XLVII Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2011
Institución organizadora:
SAIB
Resumen:
In senescing leaves, a large amount of ammonium is produced as a
result of protein hydrolysis. Most of the ammonium is reassimilated
into amino acids for export from the senescing leaf,
whereas a minor part is evaporated as ammonia from the leaf
canopy. Glutamine synthetase (GS) is a key enzyme involved in this
process. According to their subcellular localization cytosolic GS
(GS1) and chloroplastic GS (GS2) are distinguished. While GS2 is
encoded by one gene, GS1 is encoded by 3?5 genes depending on
the species. The roles of the different isoforms of GS1 are still
unresolved. During leaf senescence cytosolic GS1 fulfills a key
function in the assimilation and recycling of ammonia. This role is
particularly important during grain development and filling in
cereals, when nitrogen is remobilised. We analysed ammonium
acumulation in barley flag leaf senescence under two N fertilization
conditions. The total chlorophyll and protein content decreased,
while ammonium content increased during senescence. A
significant decrease of GS activity was observed. Symptoms of
senescence appeared latter in plants grown with high N. We have
also investigated the expression of senescence associated GS genes
by real-time PCR. We have identified at least three GS1 barley
genes; one of them increased during senescence and was downregulated
by N.
Supported by PIP 0599 and DAAD 0409.