高铵胁迫对拟南芥根系向重性的影响及机制初探  

Effect and Mechanism of High Ammonium on Root Gravitropic Response in Arabidopsis

作　　者：邹娜[1,2] 李保海[1] 强晓敏[3] 施卫明[1] 

机构地区：[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 [3]西北农林科技大学资源环境学院,陕西杨凌712100

出　　处：《土壤》2013年第1期166-171,共6页Soils

基　　金：国家973项目(2007CB109303)资助

摘　　要：向重性是决定植物根系构型的主要因素之一，对根系锚定及水分养分吸收具有重要影响。铵显著影响拟南芥根构型，尽管高铵抑制主根伸长和侧根数，然而铵对主根生长方向的研究却少有报道。本文以拟南芥为材料，利用室内培养基模拟试验，研究了高铵胁迫对根系向重性生长的影响，发现高铵胁迫不仅抑制植物生长，还影响主根的生长方向。0-30h动态观测结果表明：10mmol／L（NH4）2S04对根系的向重性反应仅表现为延缓效应，而30mmol／L（NH4）2SO4则显著减弱主根的向重性弯曲。降低基本培养基养分浓度后，铵对主根向重性反应的抑制效应可发生在较低的NH4＋浓度。外源添加Ca^2＋可部分恢复铵对主根伸长的抑制效应，却不能缓解铵对主根向重性反应的影响。不同部位分开供铵，结果显示铵对拟南芥主根向重性的影响主要是根部铵效应。上述结果表明，铵对主根向重性的影响机制部分独立于其对主根伸长的影响，也不是由于Ca^2＋缺乏引起的，而有可能与根部高铵诱导的根尖其他生理活动过程改变有关。Gravitropism is an important factor in determining root architecture and directs roots to grow downward in soil and thus may have a great affect on the uptake of water and mineral ions required for plant growth and development. Ammonium profoundly affects root architecture ofArabidopsis thaliana. Despite the inhibitory effects of high ammonium on root length and the number of lateral roots, however, very little is known concerning the influence of ammonium on root growth direction. Experiments were performed with Arabidopsis thaliana using indoor agar media for a simulation to study the effects of high ammonium on root growth direction. It was found that NH4＋ stress not only inhibited plant growth, but also affected root growth direction. Kinetics results for a 30-h assay window showed that 10 mmol/L （NH4）2804 delayed root gravitropism, while 30 mmol/L （NH4）2SO4 significantly reduced root gravitropic curvature. Reduction the nutrients in basic medium, root agravitropic response induced by NH4＋ occurred at a lower concentration. Adding Ca（NO3）2 partially restored the inhibition of NH4＋ on root elongation, but had no effects on NH4＋ induced root gravitropic angle. When NH4＋ was supplied separately to different parts of the plants, the effect of NH4＋ on root gravitropism was mainly from the root-supplied NH4＋. These results preliminarily indicate that the influence of ammonium on root growth direction is partially independent of its effect on root elongation and is not due to the deficiency of cations such as Ca^2＋, but may be related with the alteration of root physiological processes when root exposed to high NH4＋.

关 键 词：高铵 胁迫 根 向重性 

分 类 号：Q945.7[生物学—植物学]