Regulation of sulfate assimilation by nitrogen and sulfur nutrition in poplar trees
Regulation of sulfate assimilation by nitrogen and sulfur nutrition in poplar trees
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DOI：
10.1007/s00468-003-0309-4
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发表时间：
2004-05-01
影响因子：
2.3
通讯作者：
Rennenberg, H
中科院分区：
文献类型：
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作者：
Kopriva, S;Hartmann, T;Rennenberg, H
植物通过吸收无机硫酸盐，将其还原为硫化物，并将其结合到氨基酸半胱氨酸中，来满足它们对硫的需求。在草本植物中，硫酸盐同化还原的途径受到营养物质硫酸盐和硝酸盐有效性的高度调控。为研究落叶乔木硫酸盐同化规律，以杨树杂交种黑杨×白杨为模型。除了亚硫酸盐还原酶和γ-谷氨酰半胱氨酸合成酶外，该途径的酶以几种异构体存在；因此，该途径的基因组组织类似于草本植物。该途径的关键酶APS还原酶的mRNA水平在根中受缺硫3d诱导，在根中受缺氮影响降低，而在叶中仅受氮素撤除的影响。当缺乏这两种营养物质时，mRNA水平与对照植物没有什么不同。四周的缺硫对杨树植株的生长没有影响，但与对照相比，含量最高的低分子硫醇谷胱甘肽的含量降低了。硫限制导致ATP硫化酶、APS还原酶和亚硫酸盐还原酶的mRNA水平升高，这可能是一种提高硫酸盐同化途径效率的适应机制。总之，尽管发现了明显的差异，例如，硫酸盐缺乏对杨树叶片的APR没有影响，但在杨树中观察到的养分有效性对硫酸盐同化的调节与草本植物的调节相似。
Plants cover their need for sulfur by taking up inorganic sulfate, reducing it to sulfide, and incorporating it into the amino acid cysteine. In herbaceous plants the pathway of assimilatory sulfate reduction is highly regulated by the availability of the nutrients sulfate and nitrate. To investigate the regulation of sulfate assimilation in deciduous trees we used the poplar hybrid Populus tremula x P. alba as a model. The enzymes of the pathway are present in several isoforms, except for sulfite reductase and gamma-glutamylcysteine synthetase; the genomic organization of the pathway is thus similar to herbaceous plants. The mRNA level of APS reductase, the key enzyme of the pathway, was induced by 3 days of sulfur deficiency and reduced by nitrogen deficiency in the roots, whereas in the leaves it was affected only by the withdrawal of nitrogen. When both nutrients were absent, the mRNA levels did not differ from those in control plants. Four weeks of sulfur deficiency did not affect growth of the poplar plants, but the content of glutathione, the most abundant low molecular thiol, was reduced compared to control plants. Sulfur limitation resulted in an increase in mRNA levels of ATP sulfurylase, APS reductase, and sulfite reductase, probably as an adaptation mechanism to increase the efficiency of the sulfate assimilation pathway. Altogether, although distinct differences were found, e.g. no effect of sulfate deficiency on APR in poplar leaves, the regulation of sulfate assimilation by nutrient availability observed in poplar was similar to the regulation described for herbaceous plants.