Magnesium absorption, translocation, subcellular distribution and chemical forms in citrus seedlings
Magnesium absorption, translocation, subcellular distribution and chemical forms in citrus seedlings
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柑橘幼苗镁的吸收、转运、亚细胞分布和化学形态
DOI：
10.1093/treephys/tpab148
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发表时间：
2021
期刊：
影响因子：
4
通讯作者：
Guo Jiuxin
中科院分区：
文献类型：
--
作者：
Xu Hao;Luo Ziwei;Hu Wenlang;Jia Yamin;Wang Yuwen;Ye Xin;Li Yan;Chen Li-Song;Guo Jiuxin
镁（Mg）是植物生长发育所必需的大量营养元素，但柑橘缺镁对Mg转运、亚细胞分布和化学形态变化的适应机制尚不清楚。采用砂培试验，研究了0（缺镁）和2（镁充足）mmol l−1Mg2+处理对柑橘幼苗Mg适应性的影响，以及由此产生的生长和Mg转运特征。奥斯贝克'雪甘']。我们发现，镁缺乏显着降低生物量的39%，在整个植物和66%的分支器官相比，镁充足的条件下，这进一步导致随后的镁浓度和积累的变化，其在不同器官中的分布和根生长的减少。在镁充足的情况下，>50%的镁被螯合在可溶性部分中，而在镁缺乏的情况下，这减少了30%。此外，>70%的Mg以无机（42%）和水溶性（31%）形式存在，在处理和器官之间具有高流动性。缺镁胁迫下，叶片中水溶态镁比例降低，根中水溶态镁比例升高，而主茎叶中无机态镁比例升高，分支叶和根中无机态镁比例降低。而在缺镁条件下，叶和根中低迁移率的果胶酸镁和蛋白质镁、磷酸镁、重金属镁和残渣镁的比例增加，但根中果胶酸镁和蛋白质镁的比例下降。Mg转移因子表明缺镁促进了Mg从亲本向分支器官的转运，这种作用与Mg的亚细胞分布和化学形态有关。综合起来看，本研究建立了一个明确的过程来阐明Mg的吸收和转运机制，并揭示了有效提高Mg在柑橘体内流动性和有效性的可能策略。缺镁降低了柑橘对Mg的吸收，但促进了Mg从母体向分支器官的运输。Mg的50%以上被固存在可溶性部分，缺镁降低了30%。缺镁可使Mg从母体向分支器官的运输增加70%以上。缺镁可使Mg从母体向分支器官的运输减少7 Mg在叶和根中以无机态和水溶性形态存在，缺Mg时，水溶性Mg在叶中的分布减少，在根中的分布增加，Mg的迁移与其亚细胞分布和化学形态有关。
Magnesium (Mg) is an essential macronutrient for plant growth and development; however, the adaptive mechanisms of Mg deficiency to underlying changes in Mg translocation, subcellular distribution and chemical forms in citrus plants are unknown. In this study, we conducted a sand culture experiment with 0 (Mg-deficiency) or 2 (Mg-sufficiency) mmol l−1Mg2+treatments to investigate the responses underlying Mg adaptability, as well as the resulting growth and Mg transport features in citrus seedlings [Citrus sinensis(L.) Osbeckcv. ‘Xuegan’]. We found that Mg-deficiency significantly depressed biomass by 39% in the whole plant and by 66% in branch organs compared with Mg-sufficient conditions, which further resulted in a subsequent decrease in Mg concentration and accumulation with changes in its distribution in different organs and a reduction in root growth. Under Mg-sufficiency, >50% of Mg was sequestered in the soluble fraction and this was reduced by 30% under Mg-deficiency. Furthermore, >70% of Mg existed as inorganic (42%) and water-soluble (31%) forms with high mobility across treatments and organs. Under Mg-deficiency, the proportion of water-soluble Mg was reduced in leaf and increased in root, whereas the proportion of inorganic Mg increased in main stem leaves and decreased in branch leaves and root. However, under Mg-deficiency, the proportion of Mg forms with low mobility, including pectates and proteins, phosphates, oxalates and residues, was increased in leaf and root organs, with the exception of pectate and protein Mg, which was decreased in root. The Mg transfer factor showed that Mg-deficiency improved Mg transport from parent to branch organs, which was related to Mg subcellular distribution and chemical forms. Taken together, our study establishes a defined process to clarify the mechanisms of Mg absorption and translocation and reveals a possible strategy to effectively improve Mg mobility and availability in citrus plants.Mg-deficiency decreased citrus Mg uptake but improved its transport from the parent to branch organs.More than 50% of Mg was sequestrated in the soluble fraction and reduced by 30% under Mg-deficiency.More than 70% of Mg exists as inorganic and water-soluble forms in leaf and root organs.The distribution of water-soluble Mg was decreased in leaf and increased in root under Mg-deficiency.Mg mobility was related to its subcellular distribution and chemical form profiles.