4. Phytohormones orchestrate cereals’ root system architecture
Environmental factors and phytohormone shape cereals’ RSA. However, the hormonal interplay regulating RSA is very complex. Figure 1B offers a simplified overview. For further information, one can refer to recent reviews on the topic.
Auxin is the central regulator of the RSA. This is supported by the fact that most of the mutants reported being affected in their RSA are related to auxin synthesis, transport or signalling pathway. In rice, a recent reviewalso highlights auxin’s central role in root elongation and lateral and crown roots initiation and emergence. However, other hormones such as cytokinins (CKs), ethylene, abscisic acid (ABA), gibberellins, brassinosteroids and strigolactones should not stay aside.