Up-regulation and localization of asparagine synthetase in tomato leaves infected by the bacterial pathogen Pseudomonas syringae
Up-regulation and localization of asparagine synthetase in tomato leaves infected by the bacterial pathogen Pseudomonas syringae
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DOI：
10.1093/pcp/pch092
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发表时间：
2004-06-01
影响因子：
4.9
通讯作者：
de Vicente, A
中科院分区：
文献类型：
--
作者：
Olea, F;Pérez-García, A;de Vicente, A
氮代谢是基础代谢的一个方面，在植物与病原体相互作用领域尚不清楚。在我们实验室进行的先前研究中获得的证据强烈表明，在微生物发病过程中，患病组织中发生了重要的氮动员过程。本文研究了丁香假单胞菌感染番茄叶片中天冬酰胺合成酶（AS; EC 6.3.5.4）的表达规律。番茄。利用RT-PCR从侵染叶片中分离到的同源AS cDNA探针，我们观察到侵染过程中AS的高水平表达。同时，单个AS多肽也在对细菌感染的反应中积累。此外，免疫组化分析显示，侵染叶片的主要维管束韧皮部细胞和叶片次生脉中有较强的免疫染色。这些数据与先前报道的谷氨酰胺合成酶（GS1）胞质异构体的表达也在感染过程中诱导相关。综上所述，我们的研究结果表明，GS1/AS途径的存在代表了将蛋白质分解代谢释放的铵转化为天冬酰胺的代谢途径，天冬酰胺是一种氨基酸，可能在病变组织的氮动员中起主要作用。
Nitrogen metabolism is one aspect of basic metabolism, which is still quite unknown in the field of plant-pathogen interactions. Evidence derived from previous studies conducted in our laboratory strongly suggests that during microbial pathogenesis an important nitrogen mobilization process takes place in diseased tissues. Here we describe the expression pattern of asparagine synthetase (AS; EC 6.3.5.4) in tomato leaves infected by the bacterial pathogen Pseudomonas syringae pv. tomato. Using an homologous AS cDNA probe isolated by RT-PCR from infected leaves, we have observed a high level induction of AS expression during the course of infection. Concomitantly, a single AS polypeptide also accumulated in response to bacterial infection. Furthermore, immunohistochemical analysis of AS in infected leaves revealed a strong immunostaining in phloem cells of the main vascular bundles and in secondary veins of the leaf blade. These data correlate with those previously reported for expression of a cytosolic isoform of glutamine synthetase (GS1) also induced during development of the infectious process. Taken together, our results suggest the existence of a GS1/AS pathway representing a metabolic route for transferring ammonium released from protein catabolism into asparagine, an amino acid that may have a major role in nitrogen mobilization from diseased tissues.