《植物生理学报》 2013, 49(5): 463-468

不同浓度NH4⁺和K⁺处理对拟南芥突变体amos2侧根发育的影响

冯晓宇^1,2, 李光杰^1,2, 董刚强^1,2, 施卫明^1,*

1土壤与农业可持续发展国家重点实验室, 中国科学院南京土壤研究所, 南京210008; 2中国科学院大学, 北京100049

通信作者：施卫明；E-mail: wmshi@issas.ac.cn；Tel: 025-86881566

摘　要：

K+在缓解植物NH4+毒害过程中扮演着重要的角色。本文研究培养基中添加不同浓度(0.6、1.2和5.0 mmol·L-1)的K+时, 高NH4+ (30或40 mmol·L-1)对拟南芥野生型Col-0和NH4+超敏感突变体amos2侧根生长的影响。结果表明, 在较低外源K+浓度(0.6和1.2 mmol·L-1)下, 30 mmol·L-1 NH4+使amos2的侧根数量减少85%~90%, 超过对Col-0的2倍; 外源K+浓度提高到5.0mmol·L-1时更显著缓解高NH4+对amos2侧根数量的抑制作用。高NH4+对Col-0和amos2新生根区侧根数量的抑制比对成熟根区的大。时间动态的结果表明: 在低K+条件下, 高NH4+处理的初始阶段, amos2侧根的发育已开始受到比Col-0更显著的 抑制, 且amos2侧根的出现受到更明显的延时; 将外源K+浓度提高到5.0 mmol·L-1能缓解这种延时效应。可见, 在低K+条件下,AMOS2位点可能在拟南芥抵抗高NH4+对侧根的抑制过程中发挥作用, 降低NH4+/K+比可能是提高拟南芥高NH4+抗性的手段。 +毒害; 外源K+; 侧根

关键词：拟南芥; amos2突变体; NH4

收稿：2013-01-21   修定：2013-04-07

资助：国家自然科学基金青年科学基金项目(31200189)和中国科学院南京土壤研究所知识创新工程领域前沿项目 (ISSASIP1103)。

The Effects of Different Concentrations of NH₄⁺ and K⁺ Treatments on Lateral Root Development of Arabidopsis amos2 Mutant

FENG Xiao-Yu^1,2, LI Guang-Jie^1,2, DONG Gang-Qiang^1,2, SHI Wei-Ming^1,*

¹State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; ²University of Chinese Academy of Sciences, Beijing 100049, China

Corresponding author: SHI Wei-Ming; E-mail: wmshi@issas.ac.cn; Tel: 025-86881566

Abstract:

K⁺ plays an important role in the process of protecting plant species from NH₄⁺ toxicity. In this arti-cle, lateral root (LR) development of Arabidopsis wild type (Col-0) and amos2 mutant (which is overly sensi-tive to NH₄⁺ supply) was analyzed under excessive NH₄⁺ (30 or 40 mmol·L-1) with different concentrations of K⁺ (0.6, 1.2 and 5.0 mmol·L-1) added in agar medium. The results showed that high NH₄⁺ could inhibit the rela-tive number of LRs of amos2 by 85%–90% on the low external K⁺ (0.6 or 1.2 mmol·L-1), it was twice higher than that of Col-0. However, the LR development of Arabidopsis under NH₄⁺ stress could be recovered by high-er external K⁺ (5.0 mmol·L-1), especially to amos2. Furthermore, high NH₄⁺+ had more significant inhibition on the LR development of distal portion than that of proximal portion. The LRs of amos2 had been more signifi-cantly inhibited by high NH₄⁺ at the initial phase of treatment than that of Col-0, and there was also an obvious time delay on the LR development of amos2 under high NH₄⁺ and low external K⁺. Higher external K⁺ (5.0 mmol·L-1) could relieve the time delay of LR development under NH₄⁺ stress. All the results indicate that the AMOS2 locus plays an important role in the resistance to high NH₄⁺, particularly at low external K⁺, and the decrease in NH₄⁺/K⁺ ratio is a vital cause for plants to resist NH₄⁺ toxicity.

Key words: Arabidopsis thaliana; amos2 mutant; NH₄⁺ toxicity; external K⁺; lateral root