Nitric oxide is downstream of auxin regulating root growth and developmental processes.

LANTERI, M. L.; CORREA-ARAGUNDE, M.; LOMBARDO, C; LAXALT, A.M.; LAMATTINA, L.

Rosario

Conferencia; SAFV; 2008

SAFV

Auxin modulates diverse aspects of root growth and development. The root system plays an essential role in the growth and survival of plants. We have demonstrated that nitric oxide (NO), a small reactive gas, is a second messenger in the auxin signaling cascades leading to adventitious root (AR), lateral root (LR) and root hair (RH) formation. NO increases the number and length of ARs, the number of LRs, and the density and length of RHs. We have deciphered some of the molecular mechanisms triggered by NO that leads to these physiological responses. During AR formation, the NO action is accomplished by both cGMPdependent and cGMP-independent pathways. The latter involves the activation of a mitogen-activated protein kinase signaling cascade. NO also induces Ca2+-mediated signaling pathways and the activation of Ca2+-dependent protein kinases. Recent data indicates that phospholipase D-derived phosphatidic acid formation is an early signaling event during auxin- and NO-induced AR formation. The induction of LRs is achieved through a NO-modulated expression of cell cycle regulatory genes involved in G1-to-S phase transition that leads to the activation of pericycle founder cells. Finally, NO is able to induce ectopic RHs by the differentiation of atrichoblasts into trichoblasts in the root epidermis of some plant species. These and other findings concerning NO-mediated pathways that control root architecture and physiology will be presented and discussed. Supported by CONICET, ANPCyT and UNMdP.