15
Target Sites for Herbicide Action
Target Sites for Herbicide Action
TOPICS IN APPLIED CHEMISTRY Series Editors: Alan R. Katritzky, FRS
Kenan Professor of Chemistry University of Florida, Gainesville, Florida
Gebran J. Sabongi Laboratory Manager, Encapsulation Technology Center 3M, St. Paul, Minnesota
BIOCATALYSTS FOR INDUSTRY Edited by Jonathan S. Dordick
CHEMICAL TRIGGERING Reactions of Potential Utility in Industrial Processes Gebran J. Sabongi
THE CHEMISTRY AND APPLICATION OF DYES Edited by David R. Waring and Geoffrey Hallas
HIGH-TECHNOLOGY APPLICATIONS OF ORGANIC COLORANTS Peter Gregory
INFRARED ABSORBING DYES Edited by Masaru Matsuoka
STRUCTURAL ADHESIVES Edited by S. R. Hartshorn
TARGET SITES FOR HERBICIDE ACTION Edited by Ralph C. Kirkwood
A Continuation Order Plan is available for this series. A continuation order will bring delivery of each new volume immediately upon publication. Volumes are billed only upon actual shipment. For further information please contact the publisher.
Target Sites for Herbicide Action
Edited by
Ralph C. Kirkwood University of Strathclyde Glasgow, United Kingdom
Springer Science+ Business Media, LLC
Llbrary of Congress catalog1ng-ln-Publ1catlon Data
Target sttes for herbtetde act ton I edtted by Ralph C. Ktrkwood. p. CII. -- <Toptes In applted eheatstryl'
Ineludes btbltographteal referenees and Index. ISBN 978-1-4899-2435-3 ISBN 978-1-4899-2433-9 (eBook) DOI 10.1007/978-1-4899-2433-9
Effeet of herbtetdes ono 1. Weeds--Phystology. 2. Plants, 3. Herbtetdes. 4. Weeds--Control. II. Sertes.
1: Ktrkwood, R. C. (Ralph C.l
S861 1 • T36 1991 632' • 954--de20
ISBN 978-1-4899-2435-3
© 1991 Springer Science+Business Media New York Originally published by Plenum Press, New York in 1991 Softcover reprint of the hardcover 1 st edition 1991
Ali rights reserved
91-22530 CIP
No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise, without written permission from the Publisher
Contributors
Peter M. Bramley • Department of Biochemistry, Royal Holloway and Bedford New College, University of London, Egham, Surrey TW20 OEX, United Kingdom
Richard H. Bromilow • Department of Insecticides and Fungicides, AFRC Institute of Arable Crops Research, Rothamsted Experimental Station, Harpenden, Herts AL5 2JQ, United Kingdom
Keith Chamberlain • Department of Insecticides and Fungicides, AFRC Institute of Arable Crops Research, Rothamsted Experimental Station, Harpenden, Herts AL5 2JQ, United Kingdom
John R. Coggins • Department of Biochemistry, University of Glasgow, Glasgow G 12 8QQ, United Kingdom
Alan D. Dodge • School of Biological Sciences, University of Bath, Bath BA2 7 A Y, United Kingdom
John L. Harwood • Department of Biochemistry, University of Wales College of Cardiff, Cardiff CFl 1ST, United Kingdom
Kriton K. Hatzios • Department of Plant Pathology, Physiology and Weed Science, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061-0330
Ralph C. Kirkwood • Department of Bioscience and Biotechnology, University of Strathclyde, Glasgow G4 ONR, United Kingdom
v
vi Contributors
Christopher R. Leake • Environmental Sciences Department, Schering Agrochemicals Ltd., Chesterford Park Research Station, Saffron Walden, Essex CBlO lXL, United Kingdom; present address: NOR-AM Research Center, Pikeville, North Carolina 27863
David M. Mousdale • Department of Biochemistry, University of Glasgow, Glasgow G12 8QQ, United Kingdom
W. John Owen • DowElanco Ltd., Letcombe Laboratory, Letcombe Regis, Wantage, Oxon OX12 9JT, United Kingdom
Ken E. Pallett • Department of Plant Biochemistry, Rhone-Poulenc Agriculture, Ongar, Essex CMS OHW, United Kingdom
Preface
The development of chemicals to selectively control the growth of weeds has been a fascinating success story which has unfolded largely during the last four decades. The dramatic growth of herbicide research that followed the wartime discoveries of the auxin-type herbicides (phenoxyalkanoic acids) resulted in a whole range of compounds and mixtures which are used to eliminate broad- or narrow-leaved weeds from agricultural, horticultural, or forestry crops.
Today, the safe use of this armament of compounds requires our understanding of their mode of action, metabolism, and environmental persistence. The most recently developed herbicides are highly effective inhibitors of specific enzyme systems, and formulation may be an important factor determining their efficient delivery at specific target sites.
In this book, the major target sites of herbicide action are discussed in Chapters 1-5, with particular reference to photosynthesis; amino acid, lipid, and carotenoid synthesis; and other primary target sites. The effects of synergists or antagonists as modifiers of herbicide action are described in Chapter 6.
The importance of efficient target site delivery as a fundamental factor in herbicide activity and selectivity is generally recognized. Delivery of a potentially lethal dose of active ingredient may depend on a whole range of factors including the efficiency of application, retention, absorption, translocation, immobilization, and detoxification. These aspects are considered in the remaining chapters, with particular reference to the pathways and mechanisms involved in the uptake, translocation, and metabolism of soil- and foliage-applied herbicides.
vii
viii Preface
Most, if not all, of the compounds mentioned in this volume have arisen through the systematic screening of novel chemicals and the identification of active lead compounds. The subsequent development of more active analogues and suitable formulation/ delivery systems illustrates the ingenuity and expertise of the R & D chemists/biologists involved in the launch of a new herbicide. While this approach has been eminently successful, there is a view that, ideally, novel compounds should be tailored to fit specific enzyme receptor sites. This aim will be achieved only with improved understanding of the molecular architecture of the site(s) and the molecular requirements for transport into and within the plant. The approach taken in this book should serve to illuminate the problems and possible solutions.
It is hoped that this volume will be of interest and value to those concerned with scientific agriculture and horticulture, including growers, government advisors, representatives of the agrochemical industry, and researchers in herbicide activity, mode of action, or environmental fate. It should also be useful to those undergraduates and postgraduates concerned with plant biochemistry and physiology, since the study of herbicide action has led to a better understanding of the mechanisms these chemicals inhibit.
Ralph C. Kirkwood Glasgow, United Kingdom
Contents
1. Photosynthesis
Alan D. Dodge
1.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2. The General Structure of the Chloroplast and the Electron
Transport System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.3. The Organization of Photosystem II . . . . . . . . . . . . . . . . . . . . . . . 4.
1.3.1. Detailed Structure of the D1 Protein and the Herbicide Binding Site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3.2. The Consequences of Electron Transport Inhibition . . . 9 1.3.3. Modifying the D1 Protein and Engineering Herbicide
Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 1.4. The Organization of Photosystem I . . . . . . . . . . . . . . . . . . . . . . . 11
1.4.1. Herbicides Interacting with Photosystem I............ 12 1.4.2. Radical-Induced Damage . . . . . . . . . . . . . . . . . . . . . . . . . . 14 1.4.3. Tolerance to Photosystem I Herbicides. . . . . . . . . . . . . . . 15
1.5. Chloroplast Antioxidative Protective Systems............... 15 1.6. Photosynthetic Carbon Metabolism . . . . . . . . . . . . . . . . . . . . . . . 17
1.6.1. Inhibitors of the Photosynthetic Carbon Reduction (Calvin) Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
1.6.2. Inhibitors of Photorespiration . . . . . . . . . . . . . . . . . . . . . . 19 1.6.3. Inhibitors of C4 Metabolism . . . . . . . . . . . . . . . . . . . . . . . . 22
1. 7. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
ix
X Contents
2. Amino Acid Synthesis
David M. Mousdale and John R. Coggins
2.1. Amino Acid Biosynthesis in Plants . . . . . . . . . . . . . . . . . . . . . . . . 29 2.2. Glyphosate and the Shikimate Pathway . . . . . . . . . . . . . . . . . . . . 31
2.2.1. The Shikimate Pathway . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 2.2.2. 5-Enolpyruvylshikimate-3-Phosphate Synthase . . . . . . . . 34 2.2.3. Inhibition of EPSP Synthase by Glyphosate . . . . . . . . . . 34 2.2.4. EPSP Synthase and Herbicide Selectivity . . . . . . . . . . . . . 37
2.3. Inhibitors of Branched-Chain Amino Acid Biosynthesis. . . . . . 39 2.3.1. Enzymology...................................... 39 2.3.2. Herbicides as ALS Inhibitors . . . . . . . . . . . . . . . . . . . . . . . 41 2.3.3. ALS Inhibition and Herbicide Effects . . . . . . . . . . . . . . . . 42 2.3.4. Inhibition of Acetolactate Reductoisomerase. . . . . . . . . . 43
2.4. Histidine Biosynthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 2.5. Glutamine Synthetase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
2.5.1. Enzymology...................................... 45 2.5.2. Inhibitors of Glutamine Synthetase . . . . . . . . . . . . . . . . . . 45 2.5.3. Glutamine Synthetase and Phytotoxicity . . . . . . . . . . . . . 47 2.5.4. Herbicide Selectivity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
2.6. Overview: Can Inhibition of Amino Acid Biosynthesis Be Predicted? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 References............................................. 50
3. Lipid Synthesis
John L. Harwood
3.1. The Nature and Distribution of Plant Lipids . . . . . . . . . . . . . . . 57 3.2. Basic Pathways of Fatty Acid and Acyl Lipid Metabolism . . . 62 3.3. Substituted Pyridazinones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 3.4. Thiocarbamates and Their Safeners . . . . . . . . . . . . . . . . . . . . . . . 76 3.5. Aryloxyphenoxypropionates and Cyclohexanediones . . . . . . . . 80 3.6. Other Herbicides Which Affect Lipids . . . . . . . . . . . . . . . . . . . . . 89
3.6.1. Ethofumesate..................................... 89 3.6.2. Chloroacetamides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 3.6.3. Other Herbicides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
3.7. Future Prospects........................................ 91 References............................................. 91
Contents xi
4. Carotenoid Biosynthesis
Peter M. Bramley
4.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 4.2. Structure and Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 4.3. Occurrence and Functions in Plants . . . . . . . . . . . . . . . . . . . . . . . 97
4.3.1. Distribution and Subcellular Location . . . . . . . . . . . . . . . 97 4.3.2. Functions of Carotenoids in Higher Plants . . . . . . . . . . . 98
4.4. Biosynthesis............................................ 99 4.4.1. Pathways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 4.4.2. Enzymology...................................... 102 4.4.3. Regulation of Carotenoid Biosynthesis.. . . . . . . . . . . . . . 105
4.5. Experimental Approaches and Analytical Techniques in Studies on Bleaching Herbicides................................. 106 4.5.1. Carotenoid Analyses of Higher Plants, Algae, and
Cyanobacteria.................................... 106 4.5.2. Electron Microscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 4.5.3. Cell-Free Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 4.5.4. Quantitative Structure-Activity Relationships . . . . . . . . . 109
4.6. Target Sites: Theory versus Practice . . . . . . . . . . . . . . . . . . . . . . . 112 4.6.1. Enzymes......................................... 112 4.6.2. Other Target Sites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
4. 7. Future Prospects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
5. Other Primary Target Sites for Herbicides
Ken E. Pallett
5.1. Respiration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 5.2. Chlorophyll Biosynthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
5 .2.1. Inhibition of ALA Synthesis . . . . . . . . . . . . . . . . . . . . . . . . 131 5.2.2. Inhibition of ALA Dehydratase . . . . . . . . . . . . . . . . . . . . . 133 5.2.3. Inhibition of Protoporphyrinogen Oxidase. . . . . . . . . . . . 133 5.2.4. Photodynamic Herbicides . . . . . . . . . . . . . . . . . . . . . . . . . . 138
5.3. Isoprenoid Biosynthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 5.3.1. Inhibition of Isopentenyl Pyrophosphate Isomerase and
Prenyl Transferase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 5.3.2. Phytosterol Biosynthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 5.3.3. Gibberellin Biosynthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 5.3.4. Phytol Biosynthesis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
xii Contents
5.4. Microtubule Assembly and Function . . . . . . . . . . . . . . . . . . . . . . 144 5.4.1. Formation and Function of Microtubules . . . . . . . . . . . . 144 5.4.2. Herbicide Interference with Microtubule Structure and
Function......................................... 145 5.5. Cellulose Biosynthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 5.6. Protein and Nucleic Acid Biosynthesis . . . . . . . . . . . . . . . . . . . . 150 5.7. Folic Acid Biosynthesis.................................. 152 5.8. Auxin and Anti-Auxin Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
5.8.1. Auxin Herbicides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154 5.8.2. Auxin Inhibitor Herbicides . . . . . . . . . . . . . . . . . . . . . . . . . 159 5.8.3. Auxin Transport Inhibitors . . . . . . . . . . . . . . . . . . . . . . . . . 161
5.9. Concluding Remarks.................................... 161 References............................................. 161
6. Modifiers of Herbicide Action at Target Sites
Kriton K. Hatzios
6.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 6.2. Interactions of Herbicides and Modifiers: Fundamentals . . . . . 170
6.2.1. Definitions and Test Methods. . . . . . . . . . . . . . . . . . . . . . . 170 6.2.2. Mechanisms of Synergism and Antagonism . . . . . . . . . . . 172
6.3. Synergists of Herbicide Action at Target Sites . . . . . . . . . . . . . . 173 6.3.1. Synergists of Herbicides at Single Target Sites . . . . . . . . 173 6.3.2. Physiological Synergism. . . . . . . . . . . . . . . . . . . . . . . . . . . . 174 6.3.3. Other Synergists of Herbicidal Action. . . . . . . . . . . . . . . . 175
6.4. Antagonists of Herbicide Action at Target Sites. . . . . . . . . . . . . 176 6.4.1. Competition for Binding to the Same Target Site...... 176 6.4.2. Circumvention of the Target Site . . . . . . . . . . . . . . . . . . . . 180 6.4.3. Compensation of the Target Site . . . . . . . . . . . . . . . . . . . . 181
6.5. Concluding Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
7. Fate of Soil-Applied Herbicides: Factors Influencing Delivery of Active Ingredients to Target Sites
Christopher R. Leake
7 .1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189 7.2. Dissipation Mechanisms................................. 190
7.2.1. Volatilization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
Contents xiii
7.2.2. Adsorption....................................... 195 7.2.3. Transport in Solution.............................. 202
7.3. Degradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206 7 .3.1. Photochemical Degradation . . . . . . . . . . . . . . . . . . . . . . . . 206 7.3.2. Microbiological and Chemical Degradation........... 207
7.4. Conclusions............................................ 214 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
8. Pathways and Mechanisms of Uptake of Foliage-Applied Herbicides with Particular Reference to the Role of Surfactants
Ralph C. Kirkwood
8.1. The Cuticle as a Barrier to Herbicide Uptake. . . . . . . . . . . . . . . 220 8.1.1. The Structure of the Cuticle . . . . . . . . . . . . . . . . . . . . . . . . 220 8.1.2. Cuticle Wetting, Spreading, and Retention . . . . . . . . . . . 221 8.1.3. Spray Deposits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222 8.1.4. Cuticle Penetration by Herbicides . . . . . . . . . . . . . . . . . . . 223
8.2. Surfactants in Relation to Cuticle Retention and Penetration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229 8.2.1. The Role of Surfactants . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229 8.2.2. Cuticle Penetration of Surfactants . . . . . . . . . . . . . . . . . . . 231 8.2.3. The Mechanism of Surfactant Action . . . . . . . . . . . . . . . . 232
8.3. Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239 References............................................. 241
9. Pathways and Mechanisms of Transport of Herbicides in Plants
Richard H. Bromilow and Keith Chamberlain
9.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245 9.2. General Factors Defining and Controlling Systemic
~ehavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246 9.2.1. General Description of Transport Systems in Plants . . . 246 9.2.2. Sites of Action of Herbicides . . . . . . . . . . . . . . . . . . . . . . . 248 9.2.3. Physicochemical Properties and Their Role in Determin-
ing Herbicide Transport . . . . . . . . . . . . . . . . . . . . . . . . . . . 248 9.2.4. Effects of Phytotoxicity of Herbicides on Transport in
Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250 9.3. Uptake and Transport Processes for Herbicides............. 251
9.3.1. Experimental Techniques for Measuring Transport . . . . 251
xiv Contents
9.3.2. Uptake by Plants from Soil. . . . . . . . . . . . . . . . . . . . . . . . . 252 9.3.3. Uptake and Transport Following Foliar Application . . . 259
9.4. Mobilities of Herbicides by Class . . . . . . . . . . . . . . . . . . . . . . . . . 266 9.4.1. Nonionized Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . 266 9.4.2. Cations (Quatemized Amines) . . . . . . . . . . . . . . . . . . . . . . 274 9.4.3. Acids............................................ 275
9.5. Conclusions............................................ 280 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282
10. Herbicide Metabolism as a Basis for Selectivity
W. John Owen
10.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285 10.2. Evidence for the Role of Various Detoxification Mechanisms
in Herbicide Selectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286 10.2.1. Hydrolysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286 10.2.2. Reductive Deamination . . . . . . . . . . . . . . . . . . . . . . . . . . 291 10.2.3. Oxidative Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292 1 0.2.4. Glycosidation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306 10.2.5. Glutathione Conjugation......................... 307
10.3. Concluding Remarks................................... 310 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311
Chemical Names of Compounds Mentioned in the Text . . . . . . . . . . . 315
Index...................................................... 327
Target Sites for Herbicide Action
