State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, No. 71 East Beijing Road, Nanjing, 210008, China.
University of the Chinese Academy of Sciences, No. 19(A) Yuquan Road, Shijingshan District, Beijing, 100049, China.
New Phytol. 2018 Jul;219(1):259-274. doi: 10.1111/nph.15157. Epub 2018 Apr 15.
The root tip zone is regarded as the principal action site for iron (Fe) toxicity and is more sensitive than other root zones, but the mechanism underpinning this remains largely unknown. We explored the mechanism underpinning the higher sensitivity at the Arabidopsis root tip and elucidated the role of nitric oxide (NO) using NO-related mutants and pharmacological methods. Higher Fe sensitivity of the root tip is associated with reduced potassium (K ) retention. NO in root tips is increased significantly above levels elsewhere in the root and is involved in the arrest of primary root tip zone growth under excess Fe, at least in part related to NO-induced K loss via SNO1 (sensitive to nitric oxide 1)/SOS4 (salt overly sensitive 4) and reduced root tip zone cell viability. Moreover, ethylene can antagonize excess Fe-inhibited root growth and K efflux, in part by the control of root tip NO levels. We conclude that excess Fe attenuates root growth by effecting an increase in root tip zone NO, and that this attenuation is related to NO-mediated alterations in K homeostasis, partly via SNO1/SOS4.
根尖区域被认为是铁（Fe）毒性的主要作用部位，比其他根区更为敏感，但这一机制在很大程度上仍不清楚。我们利用与一氧化氮（NO）相关的突变体和药理学方法，探究了根尖区更高敏感性的潜在机制，并阐明了 NO 的作用。根尖区对铁的敏感性较高与钾（K）保留减少有关。与根其他部位相比，根尖区的 NO 水平显著增加，在过量 Fe 下，NO 参与了主根尖区生长的停滞，至少部分与 SNO1（对一氧化氮敏感 1）/SOS4（盐过度敏感 4）诱导的 K 流失和根尖区细胞活力降低有关。此外，乙烯可以通过控制根尖区 NO 水平，拮抗过量 Fe 抑制根生长和 K 外排。我们得出结论，过量 Fe 通过增加根尖区的 NO 来抑制根生长，这种抑制作用与 NO 介导的 K 稳态改变有关，部分通过 SNO1/SOS4。
