Contrasting effects of ethylene perception and biosynthesis inhibitors on germination and seedling growth of barley (Hordeum vulgare L.)

Abstract

The effects of the plant growth regulator ethylene, and of ethylene inhibitors, on barley (Hordeum vulgare L.) germination and seedling growth were investigated. Exogenous 1-aminocyclopropane-1-carboxylic acid (ACC) at 100 microM enhanced ethylene production by barley seedlings and stimulated shoot growth, whereas both germination and seedling growth were inhibited by antagonists of ethylene perception (75 microM silver ions, 100 microM 2,5-norbornadiene (NBD)). In contrast, germination was unaffected by, and root and shoot growth of seedlings was strongly stimulated by inhibitors of ethylene biosynthesis (10 microM cobalt chloride, 10 microM aminoethoxyvinylglycine (AVG)). Since the ethylene and polyamine biosynthetic pathways are linked through S:-adenosylmethionine, this prompted further explorations into the role of polyamines in germination and seedling growth. Exogenous polyamines (putrescine, spermidine and spermine) at 1 microM concentration stimulated barley seedling growth in a similar fashion to the ethylene biosynthetic inhibitors. Both polyamines and ethylene biosynthetic inhibitors reversed the inhibitory effects of ethylene perception inhibitors on germination and seedling growth. Blocking endogenous ethylene production with aminoethoxyvinylglycine enhanced the free putrescine and spermidine content of germinating barley grains. Thus endogenous polyamines may play a complementary, growth-promotive, role to ethylene in the normal course of barley germination. Further, experiments that have been carried out using inhibitors of ethylene biosynthesis may have to be re-evaluated to take the possible effect of polyamines into account.

Ethylene Enhances Water Transport in Hypoxic Aspen

“…The anionic complex of STS is rapidly transported through plant tissues (Veen, 1983) and can negate the effects of ethylene even after short treatment (Reid et al, 1980). STS inhibited the ethylene binding in carnations (Sisler et al, 1986) and reversed the effects of applied ethylene on root extension growth in lettuce (Lactuca sativa; Abeles and Wydoski, 1987) and on seedling growth of barley (Hordeum vulgare; Locke et al, 2000). In our study, the application of ethylene resulted in an increase in Q v (Fig.…”

Arabidopsis Mitogen-Activated Protein Kinase Kinases MKK1 and MKK2 Have Overlapping Functions in Defense Signaling Mediated by MEKK1, MPK4, and MKS1

“…ET was measured by gas chromatography as described by Locke et al (2000). SA and JA were measured by gas chromatography-mass spectrometry as described by Engelberth et al (2003) and Lee et al (2004), using propyl paraben and dihydrojasmonic acid as internal standards.…”

Use of silenced plants in allelopathy bioassays: a novel approach

“…Ethylene has been studied as a volatile phytohormone in experiments using exogenous applications (Lill et al 1979;Locke et al 2000; reviewed by Pierik et al 2006); here with experiments using WT and transgenic N. attenuata seedlings that lack the ability to produce ethylene, we establish that the natural release of ethylene inXuences the root growth of neighbors. This is the Wrst report demonstrating that the natural release of a volatile chemical inhibits the growth of neighboring siblings, a process called allelopathy.…”

“…N. attenuata is a Wre-chaser that germinates in the Wrst growing season after a Wre from long-lived seedbanks and therefore frequently initiates growth in dense seedling populations where intense intra-speciWc competition is the main determinant of Darwinian Wtness (Preston and Baldwin 2000). Because of the close proximity of competitors during seedling growth, the demographic importance of seedlings and their sensitivity to naturally released phytohormones, seedling growth is a commonly used parameter for evaluating growth-suppressing activities of phytohormones (Locke et al 2000). The positive correlation observed between root growth inhibition of WT receivers, the number of WT emitter seedlings that shared the common headspace, and the ethylene levels in the common headspace (Fig.…”