Nitrate Addition Alleviates Ammonium Toxicity Without Lessening Ammonium Accumulation, Organic Acid Depletion and Inorganic Cation Depletion in Arabidopsis thaliana Shoots
Nitrate Addition Alleviates Ammonium Toxicity Without Lessening Ammonium Accumulation, Organic Acid Depletion and Inorganic Cation Depletion in Arabidopsis thaliana Shoots
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DOI：
10.1093/pcp/pcs012
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发表时间：
2012-03-01
影响因子：
4.9
通讯作者：
Noguchi, Ko
中科院分区：
文献类型：
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作者：
Hachiya, Takushi;Watanabe, Chihiro K.;Noguchi, Ko
当铵是唯一的氮（N）源时，与硝酸盐是N源的情况相比，植物生长受到抑制。这通常被称为铵毒性。众所周知，硝酸盐和铵的组合作为N源可减轻这种铵毒性（铵毒性的硝酸盐依赖性减轻），但其潜在机制仍不完全清楚。在植物中，铵毒性通常伴随着有机酸和无机阳离子的消耗以及铵的积累。所有这些因素都被认为是铵毒性的可能原因。因此，我们假设硝酸盐可以通过减轻这些症状来减轻铵毒性。我们分析了生长，无机氮和阳离子含量和各种初级代谢产物的拟南芥幼苗生长在培养基上含有不同浓度的硝酸盐和/或铵。硝酸盐依赖缓解铵毒性并不伴随着有机酸和无机阳离子的减少，并没有减少铵积累。另一方面，新梢生长与新梢中硝酸盐浓度显著相关。这表明，硝酸盐依赖性缓解铵毒性与生理过程密切相关的硝酸盐信号，吸收和还原。基于转录本分析的各种基因相关的硝酸盐信号，吸收和还原，可能的潜在机制的硝酸盐依赖缓解进行了讨论。
When ammonium is the sole nitrogen (N) source, plant growth is suppressed compared with the situation where nitrate is the N source. This is commonly referred to as ammonium toxicity. It is widely known that a combination of nitrate and ammonium as N source alleviates this ammonium toxicity (nitrate-dependent alleviation of ammonium toxicity), but the underlying mechanisms are still not completely understood. In plants, ammonium toxicity is often accompanied by a depletion of organic acids and inorganic cations, and by an accumulation of ammonium. All these factors have been considered as possible causes for ammonium toxicity. Thus, we hypothesized that nitrate could alleviate ammonium toxicity by lessening these symptoms. We analyzed growth, inorganic N and cation content and various primary metabolites in shoots of Arabidopsis thaliana seedlings grown on media containing various concentrations of nitrate and/or ammonium. Nitrate-dependent alleviation of ammonium toxicity was not accompanied by less depletion of organic acids and inorganic cations, and showed no reduction in ammonium accumulation. On the other hand, shoot growth was significantly correlated with the nitrate concentration in the shoots. This suggests that nitrate-dependent alleviation of ammonium toxicity is related to physiological processes that are closely linked to nitrate signaling, uptake and reduction. Based on transcript analyses of various genes related to nitrate signaling, uptake and reduction, possible underlying mechanisms for the nitrate-dependent alleviation are discussed.