Molecular and Environmental Regulation of Root Development

Motte, H., Vanneste, S., & Beeckman, T. (2019). Molecular and Environmental Regulation of Root Development.
Annual Review of Plant Biology, 70(1). doi:10.1146/annurev-arplant-050718-100423

"4.1.3. Other nutrients. In addition to nitrogen and phosphate, other nutrients may also have a clear effect on the root system, but very little is known about the controlling mechanisms.

In Arabidopsis, sulfur, magnesium, and iron deficiencies lead to a reduction in lateral root density, whereas deficiencies in potassium, calcium, zinc, manganese, and boron result in an increased lateral root density (50, 67, 68).

With the exception of zinc-deficient roots, the increase in lateral root density is accompanied by an inhibition of primary root growth; therefore, it is not always clear to what extent lateral roots are effectively induced by the nutrient deficiency. Manganese excess is shown to have a negative effect on auxin biosynthesis and PIN4 and PIN7 expression, which is probably associated with the reduction in lateral root density (164). Similarly, an excess of iron represses PIN2 and negatively affects lateral root formation (73) while it induces AUX1 to trigger root elongation (45). Multiple other genes involved in root development might, however, be affected by iron deficiency as indicated by an in silico analysis showing iron-deficiency-specific differential expression profiles for PIN4, TIR1, LBD16, and LBD29 (45)"

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