Interaction of ethylene with indole-3-acetic acid in regulation of rooting in pea cuttings

Abstract

Cuttings of pea (Pisum sativum L . cv Marma) were treated with 1-aminocyclopropane-l-carboxylic acid (ACC) . This treatment caused increased ethylene production and reduction of root formation . The effect of 0 .1 mM ACC on the level of endogenous indole-3-acetic acid (IAA) in the rooting zone and in the shoot apex was analyzed by gas chromatography-single ion monitoring mass spectrometry or by high pressure liquid chromatography with fluorimetric detection (HPLC) . Concentrations of indole-3-acetylaspartic acid (IAAsp) in the stem bases were also determined using HPLC . The ACC treatment had little effect on the IAA level in the base measured after 24 h, but caused a considerable decrease during the 3 following days . IAAsp increased in the base on days 1, 2 and 3 and then declined . The build up of IAAsp in the base was not affected by ACC during the first two days of the treatment, but later this conjugate decreased more rapidly than in controls . No effect of the ACC treatment was found on the level of IAA in the apex . IAA (1 EiM) applied to the cuttings during 24 h reduced the number of roots formed . The possibility that IAA-induced ethylene is involved in this response was investigated .Our results support earlier evidence that the inhibitory effect of ethylene on rooting in pea cuttings is due to decreased IAA levels in the rooting zone . The inhibitory effect of applied IAA is obtained if the internal IAA level is maintained high during the first 24 h, whereas stimulation of rooting occurs if the internal IAA level remains high during an extended period of time . Our results do not support the suggestion that ethylene mediates the inhibitory effect of applied IAA .

Ethylene inhibitors enhance in vitro root formation from apple shoot cultures

“…Ethylene appeared to inhibit adventitious root formation from pea cuttings (Nordstrom and Eliasson 1993), tomato leaf discs (Coleman et al 1980) and Prunus avium shoot cultures (Biondi et al 1990), whereas it was found to stimulate root formation from Norway spruce hypocotyl segments (Bollmark and Eliasson 1990) and hazelnut cotyledons (Gonzalez et al 1991). The promotive effect of ethylene on rooting is mediated by auxin in sunflower hypocotyls (Liu and Reid 1992) and mung bean cuttings (Riov and Yang 1989).…”