玉米根系对局部硝态氮供应的生长素运输响应。
Auxin transport in maize roots in response to localized nitrate supply.
机构信息
The Key Laboratory of Plant Nutrition, MOA, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
出版信息
Ann Bot. 2010 Dec;106(6):1019-26. doi: 10.1093/aob/mcq202. Epub 2010 Oct 7.
UNLABELLED
background and aims: Roots typically respond to localized nitrate by enhancing lateral-root growth. Polar auxin transport has important roles in lateral-root formation and growth; however, it is a matter of debate whether or how auxin plays a role in the localized response of lateral roots to nitrate.
METHODS
Treating maize (Zea mays) in a split-root system, auxin levels were quantified directly and polar transport was assayed by the movement of [(3)H]IAA. The effects of exogenous auxin and polar auxin transport inhibitors were also examined.
KEY RESULTS
Auxin levels in roots decreased more in the nitrate-fed compartment than in the nitrate-free compartment and nitrate treatment appeared to inhibit shoot-to-root auxin transport. However, exogenous application of IAA only partially reduced the stimulatory effect of localized nitrate, and auxin level in the roots was similarly reduced by local applications of ammonium that did not stimulate lateral-root growth.
CONCLUSIONS
It is concluded that local applications of nitrate reduced shoot-to-root auxin transport and decreased auxin concentration in roots to a level more suitable for lateral-root growth. However, alteration of root auxin level alone is not sufficient to stimulate lateral-root growth.
未加标签
背景与目的：根通常通过增强侧根生长来响应局部硝酸盐。极性生长素运输在侧根形成和生长中具有重要作用；然而，生长素在侧根对硝酸盐的局部响应中扮演何种角色，以及如何发挥作用，这仍然存在争议。
方法
采用分根系统处理玉米（Zea mays），直接定量生长素水平，并通过[3H]IAA 的运动来测定极性运输。还研究了外源生长素和极性生长素运输抑制剂的作用。
主要结果
与无硝酸盐处理的隔室相比，硝酸盐处理的隔室中根中的生长素水平下降更多，且硝酸盐处理似乎抑制了地上部到根部的生长素运输。然而，外源施加 IAA 仅部分降低了局部硝酸盐的刺激作用，并且局部施加的铵也会降低根中的生长素水平，但不会刺激侧根生长。
结论
由此得出结论，局部施加硝酸盐会降低地上部到根部的生长素运输，并将根中的生长素浓度降低到更适合侧根生长的水平。然而，单独改变根中的生长素水平不足以刺激侧根生长。
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