Glutamine, arginine and the amino acid transporter Pt-CAT11 play important roles during senescence in poplar

• DOI: 10.1093/aob/mcq047
• Publication Date: 2010-03-18T00:56:37Z
• Authors: Jérémy Couturier; Joan Doidy; Frédéric Guinet; Daniel Wipf; Damien Blaudez; Michel Chalot
• Keywords: 0301 basic medicine; 570; STORAGE PROTEIN; ARGININE; POPULUS TRICHOCARPA; Amino Acid Transport Systems; Plant Stems; Reverse Transcriptase Polymerase Chain Reaction; Glutamine; CATIONIC AMINO ACID TRANSPORTERS; 15. Life on land; Arginine; GLUTAMINE; NITROGEN METABOLISM; Plant Leaves; 03 medical and health sciences; Populus; SENESCENCE; PLANTE LIGNEUSE; PEUPLIER; [SDV.BV]Life Sciences [q-bio]/Vegetal Biology; [SDV.BV] Life Sciences [q-bio]/Vegetal Biology; Cellular Senescence; Plant Proteins

Nitrogen (N) availability in the forest soil is extremely low and N economy has a special importance in woody plants that are able to cope with seasonal periods of growth and development over many years. Here we report on the analysis of amino acid pools and expression of key genes in the perennial species Populus trichocarpa during autumn senescence.Amino acid pools were measured throughout senescence. Expression analysis of arginine synthesis genes and cationic amino acid transporter (CAT) genes during senescence was performed. Heterologous expression in yeast mutants was performed to study Pt-CAT11 function in detail.Analysis of amino acid pools showed an increase of glutamine in leaves and an accumulation of arginine in stems during senescence. Expression of arginine biosynthesis genes suggests that arginine was preferentially synthesized from glutamine in perennial tissues. Pt-CAT11 expression increased in senescing leaves and functional characterization demonstrated that Pt-CAT11 transports glutamine.The present study established a relationship between glutamine synthesized in leaves and arginine synthesized in stems during senescence, arginine being accumulated as an N storage compound in perennial tissues such as stems. In this context, Pt-CAT11 may have a key role in N remobilization during senescence in poplar, by facilitating glutamine loading into phloem vessels.