Systemic Upregulation of MTP2-and HMA2-Mediated Zn Partitioning to the Shoot Supplements Local Zn Deficiency Responses
Systemic Upregulation of MTP2-and HMA2-Mediated Zn Partitioning to the Shoot Supplements Local Zn Deficiency Responses
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DOI：
10.1105/tpc.18.00207
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发表时间：
2018-10-01
期刊：
影响因子：
11.6
通讯作者：
Kraemer, Ute
中科院分区：
文献类型：
--
作者：
Sinclair, Scott A.;Senger, Taraif;Kraemer, Ute
微量营养素锌（Zn）的低生物可利用浓度限制了40%耕地的农业生产。在这里，我们表明，植物适应缺锌涉及系统调节。拟南芥（Arabidopsis thaliana）幼苗的生理性锌缺乏导致根的膜转运蛋白编码基因金属转运蛋白2（MTP 2）和重金属ATP酶2（HMA 2）的转录水平增加，这两个基因对根的局部锌状态没有反应。MTP 2和HMA 2在Zn从根向地上部的分配中起相加作用。MTP 2的嵌合GFP融合蛋白与MTP 2突变体互补，并定位于从侧根伸长到根毛区的外细胞层的内质网（ER）膜上。MTP 2在过敏性酵母突变体中恢复锌耐受性这些结果是一致的细胞对细胞的运动，锌对根血管内的ER管腔连续通过连丝的胞间连丝，锌缺乏。先前描述的锌缺乏反应包括靶基因的转录激活，包括锌调节转运蛋白铁调节转运蛋白基因ZIP 4和ZIP 9，通过F-组bZIP转录因子bZIP 19和bZIP 23。我们发现，ZIP 4和ZIP 9响应本地锌的根和芽的状态，在这里确定的系统性调节相反。我们的研究结果与作物管理和改善人类营养性锌缺乏症有关，锌缺乏症影响了世界30%至50%的人口。
Low bioavailable concentrations of the micronutrient zinc (Zn) limit agricultural production on 40% of cultivated land. Here, we demonstrate that plant acclimation to Zn deficiency involves systemic regulation. Physiological Zn deficiency of Arabidopsis thaliana shoots results in increased root transcript levels of the membrane transport protein-encoding genes METAL TRANSPORT PROTEIN2 (MTP2) and HEAVY METAL ATPASE2 (HMA2), which are unresponsive to the local Zn status of roots. MTP2 and HMA2 act additively in the partitioning of Zn from roots to shoots. Chimeric GFP fusion proteins of MTP2 complement an mtp2 mutant and localize in the endoplasmic reticulum (ER) membrane of the outer cell layers from elongation to root hair zone of lateral roots. MTP2 restores Zn tolerance in a hypersensitive yeast mutant. These results are consistent with cell-to-cell movement of Zn toward the root vasculature inside the ER-luminal continuum through the desmotubules of plasmodesmata, under Zn deficiency. The previously described Zn deficiency response comprises transcriptional activation of target genes, including ZINC-REGULATED TRANSPORTER IRON-REGULATED TRANSPORTER PROTEIN genes ZIP4 and ZIP9, by the F-group bZIP transcription factors bZIP19 and bZIP23. We show that ZIP4 and ZIP9 respond to the local Zn status in both roots and shoots, in contrast to the systemic regulation identified here. Our findings are relevant for crop management and improvement toward combating human nutritional Zn deficiency that affects 30 to 50% of the world's population.