Ascorbate metabolism in rice genotypes differing in zinc efficiency
Ascorbate metabolism in rice genotypes differing in zinc efficiency
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DOI：
10.1007/s00425-013-1978-x
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发表时间：
2014-02-01
期刊：
影响因子：
4.3
通讯作者：
Frei, Michael
中科院分区：
文献类型：
--
作者：
Hoeller, Stefanie;Hajirezaei, Mohammad-Reza;Frei, Michael
以水稻（Oryza sativa L.）不同基因型为对象，研究了锌（Zn）缺乏对地上部代谢物的影响，尤其关注抗坏血酸（AsA）的生物合成、循环和分解代谢。将基因型IR74（敏感型）和RIL46（耐受型）进行-Zn处理和对照处理，持续3周，并在代表胁迫前阶段、可见胁迫出现以及严重可见胁迫的三个不同阶段取样。在敏感基因型中，可见症状的出现伴随着脂质过氧化作用的增强和AsA浓度的降低，而在耐受基因型中则没有这种情况。耐受型RIL46在低锌胁迫下，参与甘露糖/l -半乳糖途径合成AsA的几个基因的转录水平提高，并且一个参与假定的替代肌醇途径的基因显著上调。大多数AsA前体的水平受到锌缺乏的负面影响，但RIL46非磷酸化前体的水平一直较高。AsA分解代谢产物如草酸和苏糖酸在两种基因型中均未积累，这表明AsA降解对IR74中胁迫诱导的AsA库下降没有影响。可能有助于RIL46耐受性的其他因素包括在 -Zn胁迫下脯氨酸水平几乎提高了五倍以及海藻糖含量显著更高。因此，这些化合物在AsA代谢和锌效率中的作用值得进一步关注。
Effects of zinc (Zn) deficiency on shoot metabolites were investigated in contrasting rice (Oryza sativa L.) genotypes with special focus on ascorbic acid (AsA) biosynthesis, recycling, and catabolism. The genotypes IR74 (sensitive) and RIL46 (tolerant) were subjected to -Zn and control treatments for 3 weeks, and samples were taken at three different stages representing the pre-stress phase, emergence of visible stress, and severe visible stress. The emergence of visible symptoms was paralleled by an increase in lipid peroxidation and a decrease in AsA concentration in the sensitive, but not in the tolerant genotype. The tolerant RIL46 showed enhanced transcript levels of several genes involved in the mannose/l-galactose pathway to AsA biosynthesis, and significant up-regulation of a gene involved in the putative alternative myo-inositol pathway under low Zn stress. The level of most AsA precursors was negatively affected by Zn deficiency, but RIL46 had a constitutively higher level of non-phosphorylated precursors. Products of AsA catabolism such as oxalate and threonate did not accumulate in either genotype, suggesting that AsA degradation did not contribute to the stress-induced decline of the AsA pool in IR74. Further factors possibly contributing to tolerance in RIL46 included an almost fivefold higher proline level under -Zn stress and significantly higher trehalose content. The implications of these compounds in AsA metabolism and Zn efficiency thus deserve further attention.