A convenient method was devised for the fractionation of aliphatic polyamines (PAs), 1-aminocyclopropane-1-carboxylic acid (ACC), and their conjugated forms using a cation exchange resin, and applied to the floral organs of Hibiscus syriacus L. 'Diana'. A batch-wise use of the cation exchange resin to the acid extracts of the Hibiscus flower effectively separated the ACC-conjugate from free ACC, free PAs, and PA-conjugates. Good recovery rates, showing over 90% for PAs and 76-97% for ACC, were obtained when known amounts of ACC and PAs were added to the tissue extract. The amounts of these cellular compounds were determined in the petal, sepal, ovary, and style with stigma (+ stamen) collected at two different stages (flower opening and flower senescence showing complete petal in-rolling). Both ACC and ACC-conjugate, which are generally associated with tissue senescence, were consistently detected in all organs even immediately after flower opening, but their concentrations, especially that of the ACC-conjugate in the ovary, greatly increased in the senescent flowers. As regards the free PA levels, a high concentration of spermidine was found in the ovary, and its level was maintained even when the petals wilted. PA-conjugates bound to small molecules decreased in the ovaries of senescent flowers, while the PA-conjugates bound to macromolecules remained very low in all organs at the two different flower stages. The present method seems applicable to a quantitative analysis of these physiologically important compounds in a variety of plant tissues, despite the fact that their extracts contain highly viscous materials that generally reduce the recovery rate of ACC.
Involvement of ethylene was investigated in the physiological mechanism of Clomeprop [2-(2, 4-dichloro-m-tolyloxy) propionanilide] -or its hydrolytic metabolite DMPA [2-(2, 4-dichloro-m-tolyloxy)propionic acid] -induced electrolyte leakage from radish roots. The treatment of DMPA to radish roots caused increase of electrolyte leakage from the roots, suppression of the root growth and stimulation of ethylene production. Although ethylene action inhibitors, 2, 5-norbornadiene (NBD) and cispropenylphosphonic acid (PPOH), did not suppress ethylene evolution from the DMPAtreated radish roots for the first 24 hrs, these compounds suppressed the electrolyte leakage and to some extent restored the growth of lateral roots. Evan's blue dye tests revealed that death of the root cells occurred 12 hr after the DMPA treatment. This indicated that the increase in electrolyte leakage preceded the death of the root cells. These results suggest that the ethylene induced by DMPA is attributable to the leakage of electrolyte from the radish roots.
Involvement of active oxygen in clomeprop [2-(2,4-dichloro-m-tolyloxy) propionanilide] hydrolytic metabolite DMPA [2-(2,4-dichloro-m-tolyloxy) propionic acid]-induced electrolyte leakage from radish roots was investigated. Treatment of DMPA to radish roots caused an increase of electrolyte leakage from the roots and suppression of lateral root growth. Some scavengers of active oxygen species reduced the DMPA-induced ion leakage; in particular, singlet oxygen scavengers, 1, 4-diazabicyclo-[2,2,2]octane (dabco) and L-histidine, significantly supressed the leakage and restored the growth of lateral roots. Root-applied free radical scavengers or singlet oxygen scavengers also suppressed the DMPA-enhanced peroxidation of lipids in radish roots to some extent. However, pre-treatment of free radical scavengers or singlet oxygen scavengers to roots had no effect on DMPA-induced ethylene production. These results suggest that active oxygen is directly involved in the DMPA-induced electrolyte leakage from radish roots and growth inhibition of lateral roots.
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