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Title:Examination of 2,4-D tolerance in perennial Glycine species and the involvement of cytochrome P-450 as a tolerance mechanism
Author(s):White, Randall H.
Doctoral Committee Chair(s):Liebl, Rex A.
Department / Program:Agronomy
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Agriculture, Agronomy
Biology, Plant Physiology
Abstract:High levels of tolerance to 2,4-D ((2,4-dichlorophenoxy)acetic acid) were expressed at the cell and whole plant level by several accessions of wild perennial Glycine species. Heterotrophic cell suspension cultures of soybean (Glycine max (L.) Merr.) and four perennial Glycine accessions were used to investigate ($\sp{14}$C) 2,4-D uptake and metabolism. Uptake of 2,4-D was similar between soybean and the perennials. However, soybean metabolized almost 60% less 2,4-D than the perennials at an equivalent 2,4-D concentration. The primary metabolite produced by the tolerant perennial accessions was the glycoside conjugate of 4-OH-2,5-D. Soybean and less tolerant perennials lines generated primarily amino acid conjugates of 2,4-D.
The P-450 inhibitor tetcyclasis significantly reduced 2,4-D tolerance of the perennial Glycine tabacina accession IL344 by inhibiting 2,4-D metabolism 60% and formation of the hydroxylated metabolites by 80%. Tetcyclasis had no effect on soybean tolerance or 2,4-D metabolism. IL344 had 3-times more cytochrome P-450 protein (60 pmol/mg microsomal protein) than soybean and expressed one constitutive 46 kD microsomal P-450 polypeptide that strongly cross-reacted to antisera raised to avocado P-450. Soybean had a single inducible (by 2,4-D treatment) P-450 polypeptide of similar molecular weight. Ultrastructural observations were made using transmission electron microscopy and revealed that IL344 had a large distribution of smooth endoplasmic reticulum as well as convoluted nuclear membrane. Both represent indirect ultrastructural evidence for the localization of cytochrome P-450, which was verified using immunocytochemistry (immunogold labelling). In contrast, rough endoplasmic reticulum predominated in soybean.
Issue Date:1990
Rights Information:Copyright 1990 White, Randall H.
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9114460
OCLC Identifier:(UMI)AAI9114460

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