Involvement of Phytohormones in Plant Responses to Ozone

Abstract

Among various contaminants, ozone (O 3 ) is considered the most ubiquitous and phytotoxic atmospheric pollutant in industrialized and developing countries. It causes extensive risks for plant life, in terms of survival and productivity of wild and cultivated species. Plant response to O 3 resembles the biotic defense reactions and includes two steps: the first is a biphasic oxidative burst with a massive, rapid, and transient increase in apoplastic reactive oxygen species (ROS) production; the second is the induction of the hypersensitive response (HR) and systemic acquired resistance (SAR). In particular, the acute O 3 exposure (high concentrations for a few hours) results in the activation of programmed cell death (PCD) response that interacts with the synthesis of several hormones and other signaling molecules. The cross talk among all these molecules and their complex and interconnected signaling pathways are more important to determine (1) the initiation, propagation, and containment of O 3 -induced cell death, (2) the degree of the sensitivity of plants to this contaminant, and (3) the regulatory potential that plants have to promptly respond to oxidative stress. The present chapter reviews the role of phytohormones (such as ethylene, abscisic acid, gibberellins, auxins, and cytokinins) and other signaling molecules (such as salicylic and jasmonic acids, proline, and brassinosteroids), as well as their synergistic and antagonistic effects, in the complex signaling pathway involved in plant responses to O 3 stress.

O3-Induced Leaf Senescence in Tomato Plants Is Ethylene Signaling-Dependent and Enhances the Population Abundance of Bemisia tabaci

“…Hormone-dependent signals can act both independently and interactively to modulate the plant response to climate change (elevated CO 2 or O 3 ) and insect infestation ( Baier et al, 2005 ; Tamaoki, 2008 ; Erb et al, 2012 ; Zavala et al, 2013 ; Pellegrini et al, 2016 ). The hormone-mediated changes in host plant phenotypes under climate change can further affect the performance of herbivorous insects ( Guo et al, 2014 , 2017 ).…”

O3-Induced Priming Defense Associated With the Abscisic Acid Signaling Pathway Enhances Plant Resistance to Bemisia tabaci

“…Greenhouse gases, such as elevated CO 2 or O 3 , can modulate phytohormone-dependent signals in plants (Tamaoki, 2008;Pellegrini et al, 2016), and such priming defenses have significant consequences for the performance of herbivorous insects (Robinson et al, 2012;Zavala et al, 2013). In this study, we reported that elevated O 3 induced callose deposition in tomato plants and therefore enhanced plant resistance to B. tabaci in terms of reducing feeding efficiency and population abundance.…”

Losing the Warning Signal: Drought Compromises the Cross-Talk of Signaling Molecules in Quercus ilex Exposed to Ozone

“…Signaling and cell death in O 3 -exposed plants have been reviewed by several authors (e.g., Rao et al, 2000; Rao and Davis, 2001; Kangasjärvi et al, 2005; Tamaoki, 2008; Vainonen and Kangasjärvi, 2015; Carmody et al, 2016; Pellegrini et al, 2016). Different plants use many hydraulic and chemical signals to tune their sensing of water deficit (Wilkinson and Davies, 2010).…”

“…This is a physiological process that selectively targets and eliminates unwanted cells in response to a variety of biotic and abiotic stimuli ( Apel and Hirt, 2004 ). PCD resembles the hypersensitive response (HR) observed in several plant-pathogen interactions, which often precedes the acquisition of a systemic resistance by plants ( Kangasjärvi et al, 1994 ; Rao et al, 2000 ; Pellegrini et al, 2013 ; Vainonen and Kangasjärvi, 2015 ; Pellegrini et al, 2016 ). O 3 entering the leaves first induces a biphasic oxidative burst with a massive, rapid and transient increase in apoplastic reactive oxygen species (ROS), which is the main event leading to PCD activation ( Langebartels et al, 2002 ) Similarly, an oxidative burst was usually observed in plants under drought ( Smirnoff, 1993 ; Miller et al, 2010 ; Noctor et al, 2014 ) and the drought-triggered ROS production can elicit acclimatory events ( Smirnoff, 1993 ).…”

“…The signaling pathways activated by O 3 are integrated into a complex regulatory system involving ROS, plant hormones [e.g., ethylene (ET) and abscisic acid (ABA)], signaling molecules [e.g., salicylic acid (SA) and jasmonic acid (JA)], and secondary messengers (e.g., Ca 2+ ). Signaling and cell death in O 3 -exposed plants have been reviewed by several authors (e.g., Rao et al, 2000 ; Rao and Davis, 2001 ; Kangasjärvi et al, 2005 ; Tamaoki, 2008 ; Vainonen and Kangasjärvi, 2015 ; Carmody et al, 2016 ; Pellegrini et al, 2016 ). Different plants use many hydraulic and chemical signals to tune their sensing of water deficit ( Wilkinson and Davies, 2010 ).…”