1. Low nitrogen induces root elongation via auxin-induced acid growth and auxin-regulated target of rapamycin (TOR) pathway in maize.
- Author
-
Sun X, Chen H, Wang P, Chen F, Yuan L, and Mi G
- Subjects
- Meristem metabolism, Plant Roots drug effects, Plant Roots metabolism, Real-Time Polymerase Chain Reaction, Zea mays drug effects, Zea mays metabolism, Indoleacetic Acids metabolism, Nitrogen deficiency, Plant Growth Regulators metabolism, Plant Roots growth & development, Signal Transduction physiology, TOR Serine-Threonine Kinases metabolism, Zea mays growth & development
- Abstract
Under low nitrogen (N) supply, an important adaption of the maize root system is to promote the root elongation so as to increase N uptake from a larger soil space. The underlying physiological mechanism is largely unknown. In the present study, two maize inbred lines (Ye478 and Wu312) were used to study the possible involvement of the auxin and target of rapamycin (TOR) pathway in low-N-induced root elongation. Compared to Wu312, primary root elongation of Ye478 was more sensitive to low nitrate supply. Correspondingly, more auxin was accumulated in the root tip, and more protons were secreted, increasing the acidity of the apoplast space. On the other hand, low-N-induced root elongation was greatly reduced when shoot-to-root auxin transport was inhibited by applying N-1-naphthylphthalamic acid (NPA) at the plant base or by pruning the top leaf where auxin is mostly synthesized. Furthermore, exogenous application of TOR inhibitor also eliminated the response of root elongation under low N. The content of TOR kinase and the expression of TOR pathway-related genes were significantly changed when shoot-to-root auxin transport was reduced by NPA treatment. Taken together, it is concluded that low-N stress increases shoot-to-root auxin transport which enhances root elongation via auxin-dependent acid growth and the auxin-regulated TOR pathway in maize., (Copyright © 2020 Elsevier GmbH. All rights reserved.)
- Published
- 2020
- Full Text
- View/download PDF