Fine control of aerenchyma and lateral root development through Aux/IAA- and ARF-dependent auxin signaling ($) (PNAS)

Auxin plays a major role in plant development and can alter the developmental program following the stress response. In this paper, Yamauchi et al., have identified the auxin signaling cascade involved in the development of aerenchyma and regulators of this auxin signaling might also be involved in lateral root development. Aerenchyma is a gas-filled space in plant root tissue arising through programmed cell death which is formed constitutively in rice roots. The formation of aerenchyma is induced further under waterlogged/ oxygen-deficient condition and this process is dependent on auxin signaling. The auxin co-receptor Aux/IAA protein, IAA13 is shown to interact with the AUXIN RESPONSE FACTOR, ARF19. Increased auxin levels in cells cause degradation of IAA13 to release ARF19 repression and activation of LBD1-8 (lateral organ boundary domain (LBD) containing protein). Proper auxin levels and the subsequent LBD1-8 activation by ARF19 is crucial for aerenchyma formation as well as lateral root development in rice roots under optimal growth condition. Summary by Suresh Damodaran. PNAS, DOI: https://doi.org/10.1073/pnas.1907181116