Targeted expression of SbMATE in the root distal transition zone is responsible for sorghum aluminum resistance
Targeted expression of SbMATE in the root distal transition zone is responsible for sorghum aluminum resistance
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DOI：
10.1111/tpj.12290
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发表时间：
2013-10-01
期刊：
影响因子：
7.2
通讯作者：
Kochian, Leon V.
中科院分区：
文献类型：
--
作者：
Sivaguru, Mayandi;Liu, Jiping;Kochian, Leon V.
铝毒是酸性土壤上作物生产的主要限制因素之一。高粱对铝的抗性主要是通过铝激活的根尖柠檬酸分泌来实现的，而这种分泌是由SbMATE编码的质膜定位的柠檬酸外排转运蛋白介导的。在这里，我们精确地定位组织和细胞特异性铝毒性反应，以及SbMATE基因和蛋白质的表达在根尖的铝抗性近等基因系（NIL）。我们发现，铝诱导最大的细胞损伤和活性氧的产生，特别是在根尖后1- 3 mm的区域，从细胞分裂到细胞伸长的过渡发生在根尖远端过渡区（DTZ）。这些结果表明，根DTZ是根铝应力的主要区域。此外，铝诱导的SbMATE基因和蛋白质的表达，具体定位于表皮和外皮层细胞层的DTZ在铝抗性近等离子体，和铝诱导的SbMATE表达的时间过程和铝诱导的损伤的根的恢复的开始是完全一致的。这些结果表明，SbMATE基因和蛋白质的表达诱导时，根细胞经历最大的铝胁迫。因此，抗铝高粱植物已经发展出一种有效的策略，以精确定位根柠檬酸分泌物的最大铝诱导的根损伤的特定网站，最大限度地减少植物碳损失，同时最大限度地保护最容易受到铝损害的根细胞。
Aluminum (Al) toxicity is one of the major limiting factors for crop production on acid soils that comprise significant portions of the world's lands. Aluminum resistance in the cereal crop Sorghum bicolor is mainly achieved by Al-activated root apical citrate exudation, which is mediated by the plasma membrane localized citrate efflux transporter encoded by SbMATE. Here we precisely localize tissue- and cell-specific Al toxicity responses as well as SbMATE gene and protein expression in root tips of an Al-resistant near-isogenic line (NIL). We found that Al induced the greatest cell damage and generation of reactive oxygen species specifically in the root distal transition zone (DTZ), a region 1-3mm behind the root tip where transition from cell division to cell elongation occurs. These findings indicate that the root DTZ is the primary region of root Al stress. Furthermore, Al-induced SbMATE gene and protein expression were specifically localized to the epidermal and outer cortical cell layers of the DTZ in the Al-resistant NIL, and the process was precisely coincident with the time course of Al induction of SbMATE expression and the onset of the recovery of roots from Al-induced damage. These findings show that SbMATE gene and protein expression are induced when and where the root cells experience the greatest Al stress. Hence, Al-resistant sorghum plants have evolved an effective strategy to precisely localize root citrate exudation to the specific site of greatest Al-induced root damage, which minimizes plant carbon loss while maximizing protection of the root cells most susceptible to Al damage.