The effects of ethylene in the root environment upon the development of barley

Abstract

Following observations that ethylene can occur in anaerobic or partially anaerobic soils at concentrations which can affect plant growth, shoot and root growth of barley plants, maintained in solution culture, were examined after long-term exposure of the roots to ethylene in air; the subsequent growth on transfer to a similar but ethylene-free environment was also studied. Both root and shoot dry weights were reduced slightly by the ethylene t r e a t m e n t ; seminal root extension was inhibited greatly while lateral root growth was stimulated; absorption of ions and their transport from root to shoot within the plant was not affected. On transfer to an ethylene free environment the extension rate of the seminal axes increased markedly and was the greater the shorter the period of the preceding ethylene t r e a t m e n t ; the extension of laterals initiated during the ethylene t r e a t m e n t was stimulated greatly but the growth of those formed subsequently was inhibited.Split root experiments showed that on any plant only those roots actually exposed to ethylene became modified by the gas while those remaining in an ethylene free environment were typical of roots of untreated plants.

Localization of ethylene biosynthesis in roots of sunflower (Helianthus annuus) seedlings

“…Primary root elongation is ACC metabolism in different parts ofthe root, inhibited by ethyiene (Whalen and Feldman 1988), but Ethylene has been implicated in many aspects of root lateral elongation and root hair production can be ingrowth and development. Root growth is influenced by creased (Crossett and Campbell 1975), soil texture and ethylene seems to play a role in thigmo-Since the root is a heterogeneous organ and the differmorphogenesis (Sarquis et al, 1992) and penetration of ent parts of the root may respond differently to environthe substrate by the root tip (Zacarias and Reid 1992), mental stimuli, and because ethylene has beeti impli-cated in the reaction to such stimuli, levels of ethylene and ACC may vary within different portions of the root. Studies on the distribution of ethylene synthesis in shoots (Schierle et al, 1989) and ACC metabolism in flowers (Nichols et al, 1983) show that these processes are not the satne throughout all parts of these structures, ACC metabolism in roots may show a similar degree of variation, Ethylene metabolism is controlled through the regulation of ACC production, via ACC synthase (Kende andBoiler 1981, Konze andKwiatkowski 1981), conjugation ofthe ACC to N-malonyl-ACC (MACC) , Liu et al, 1985 and ACC conversion to ethylene by the regulation of ACC oxidase activity.…”

Hormonal Effects on Growth and Morphology of Normal and Hairy Roots of Hyoscyamus muticus

“…Primary root elongation is generally inhibited by ethylene, but LR elongation and root hair production can be increased (Crossett and Campbell 1975). In this study, the inhibition of endogenous ethylene production by AVG stimulated both PR and LR elongation, whereas the complete absence of root hairs in T roots of H. muticus treated with 100 M silver thiosulfate, an ethylene antagonist, was reported previously (Biondi et al 1995).…”

Structure and Function of Roots

“…Root swelling as a result of Al excess resembled ethylene effects on barley (Crosset and Campbell, 1971). Root swelling as a result of Al excess resembled ethylene effects on barley (Crosset and Campbell, 1971).…”