Glutamine, arginine and the amino acid transporter Pt-CAT11 play important roles during senescence in poplar
Glutamine, arginine and the amino acid transporter Pt-CAT11 play important roles during senescence in poplar
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DOI：
10.1093/aob/mcq047
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发表时间：
2010-06-01
期刊：
影响因子：
4.2
通讯作者：
Chalot, Michel
中科院分区：
文献类型：
--
作者：
Couturier, Jeremy;Doidy, Joan;Chalot, Michel
森林土壤中的氮（N）有效性极低，并且N经济对于能够科普多年的季节性生长和发育的木本植物具有特别重要的意义。本文报道了多年生植物大果杨秋季衰老过程中氨基酸库的分析和关键基因的表达。精氨酸合成基因和阳离子氨基酸转运蛋白（CAT）基因在衰老过程中的表达分析。通过在酵母突变体中进行异源表达来详细研究Pt-CAT 11的功能。氨基酸库分析表明，在衰老过程中，叶片中谷氨酰胺的增加和茎中精氨酸的积累。精氨酸生物合成基因的表达表明，精氨酸优先合成谷氨酰胺在多年生植物组织。Pt-CAT 11在衰老叶片中表达增加，功能特性表明Pt-CAT 11转运谷氨酰胺，本研究建立了衰老过程中叶片合成的谷氨酰胺与茎合成的精氨酸之间的关系，精氨酸作为氮储存化合物在多年生组织如茎中积累。在这种情况下，Pt-CAT 11可能有一个关键的作用，在白杨衰老过程中的N再动员，通过促进谷氨酰胺加载到韧皮部血管。
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.