Nitric oxide is downstream auxin and is required for inducing adventitious root formation in herbaceous and woody plants

LANTERI MARÍA LUCIANA, PAGNUSSAT GABRIELA, LAXALT ANA MARÍA, LAMATTINA LORENZO

Adventitious root formation in forest trees and woody horticultural crops - from genes to applications

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Lugar: Kerala, India; Año: 2008;

Adventitious root (AR) formation is a very complex process under the control of both endogenous (mainly plant growth regulators) and exogenous (light, temperature, wounding, etc) factors. Among plant growth regulators, auxin plays a central role in integrating and synchronizing downstream signaling from endogenous and exogenous stimuli leading to AR formation. This chapter describes and compiles physiological, biochemical and molecular evidence supporting the requirement for nitric oxide (NO) in auxin-induced AR formation. NO is a recently characterized signal molecule in plants involved in many growth, developmental and stress physiology-related processes. Auxin induces NO synthesis in the base of cucumber (Cucumis sativus) hypocotyls, a process shown to be essential to switch on the program triggering AR formation. NO has been demonstrated to be necessary for increasing the number and length of ARs in cucumber explants and other plant species. An auxin-induced increase of NO concentration activates a signaling pathway involving cyclic GMP (cGMP), mitogen-activated protein kinases (MAPKs), Ca2+, Ca2+-dependent protein kinases (CDPKs), and phospholipases C and D, leading to an enhanced AR formation. In addition, the capability of NO to enhance the number of ARs has also been demonstrated in nurseries with the application of NO-donors under different protocols to stem cuttings of woody plants during propagation. As a result, treatments with NO donors positively influence the survival rate of cuttings, a central step in vegetative propagation. These results constitute the basis for the emergence of new rooting treatments.