Ethylene: Inhibitor and Stimulator of Plant Growth

Abstract

Ethylene is a gaseous hormone which plays an essential role in a myriad of plant developmental processes. It promotes root hair formation, flowering in a number of species, fruit ripening and abscission and leaf and petal abscission. Ethylene can stimulate growth in hypocotyls of light-grown plants, and shoot growth in shaded conditions. On the other hand, it inhibits root growth, and hypocotyl elongation in the dark. In recent years, compelling molecular evidence has been gathered to support intricate connections between ethylene and other hormonal pathways that yield its well-known effects on plant growth. In this chapter, we will discuss the role of ethylene in both growth-stimulating and growth-inhibiting processes.

Comparison of Growth Responses to Auxin 1-Naphthaleneacetic Acid and the Ethylene Precursor 1-Aminocyclopropane-1-Carboxilic Acid in Maize Seedling Root

“…Very low concentrations of auxin applied externally may stimulate elongation (Evans et al, 1994), but the typical response of roots to exogenous auxin is inhibited elongation and enhanced swelling (Eliasson et al, 1989). Similar effects have been found with ethylene, which at very low concentrations may promote root elongation and at high concentrations has been shown to inhibit root elongation and increase root diameter (Jackson, 1991;Dolan, 1997;de Cnodder et al, 2005;Dugardeyn and van der Straeten, 2008;Alarcón et al, 2009a). Auxin has been suggested to play an important role in root growth and development, and its interactions with ethylene have been explained with two alternative hypotheses.…”

Analysis of the genetic basis of plant height-related traits in response to ethylene by QTL mapping in maize (Zea mays L.)

“…ET normally causes the inhibition of stem elongation [ 6 , 11 ]. However, ET treatment also causes a stunted and thick inflorescence stem, which is also observed in the untreated ctr1 mutant of Arabidopsis [ 12 ]. Rapid shoot growth in aquatic species is controlled by the levels of ET synthesis and action.…”

“…Rapid shoot growth in aquatic species is controlled by the levels of ET synthesis and action. Thus, the elongation response of deepwater rice, commonly known as ‘supergrowth’, is primarily dependent on the hypoxic induction of ACC synthase [ 12 – 14 ]. The resulting increase in ET modulates the balance between gibberellic acid (GA) and abscisic acid (ABA) and induces stem elongation [ 12 , 15 – 16 ].…”

“…Thus, the elongation response of deepwater rice, commonly known as ‘supergrowth’, is primarily dependent on the hypoxic induction of ACC synthase [ 12 – 14 ]. The resulting increase in ET modulates the balance between gibberellic acid (GA) and abscisic acid (ABA) and induces stem elongation [ 12 , 15 – 16 ]. Plant height has been shown to decrease with decreasing internode length upon ET application in maize, barley, oats, and wheat [ 17 – 22 ].…”