Nitrate: A Crucial Signal during Lateral Roots Development

Abstract

Root plasticity is an important trait for plants to forage nutrient and adapt to survival in a complicated environment. Lateral roots (LRs) are generally more sensitive than primary roots in response to changing environmental conditions. As the main source of nitrogen for most higher plants, nitrate acting as a signal has received great attention in the regulation of LR development. In general, there are dual effects including stimulatory and inhibitory of low nitrate on LR development; while high nitrate supply has an inhibitory effect on LR development; nitrate heterogeneity also has a stimulatory effect on LR development in [Formula: see text]- rich zone. Here, we focus on recent progresses in the role of a nitrate signal in the regulation of the LRs development.

Keywords: LR development; hormones; lateral roots; nitrate; primary roots.

FIGURE 1

Multiple signaling pathways regulating the LR response to the low ${\mathrm{NO}}_{\mathrm{3}}^{\mathrm{–}}$ or N deficiency in plants. Only those pathways discussed in the present review are depicted. The tip of lines with arrows and horizontal lines indicate the positive and negative signaling steps, respectively. NR, nitrate reductase. See text for further explanation.

FIGURE 2

Sensing of high nitrate signals through hormones-mediated LR development. The tip of lines with arrows and horizontal lines indicate the positive and negative signaling steps, respectively. NR, nitrate reductase; NiR, nitrite reductase. See text for further information.

FIGURE 3

Schematic drawing illustrating the current knowledge on how heterogeneous nitrate influences the LR development. The tip of lines with arrows and horizontal lines indicate the positive and negative signaling steps, respectively. See text for further information.