Targets for Bleaching Herbicides

Carotenoid Biosynthesis and Phytotoxic Effects of Bleaching Herbicides 4.1.2.1 Targets for Bleaching Herbicides 

Bleaching may be a result of photooxidative events generated within the plant cell or chloroplast, leading to the destruction of the plant pigments or direct inhibition of pigment biosynthesis, whereby carotenoid and chlorophyll formation is prevented [5]. 

With carotenoid biosynthesis, plastoquinone is involved as an electron acceptor, which we encounter further in photosynthetic electron transport [2]. An important precursor in the synthesis of plastoquinone, which also serves as a cofactor for the PDS enzyme, is homogentisic acid, which is formed from 4-hydroxyphenyl-pyruvate by 4-hydroxyphenylpyruvate dioxygenase (HPPD) 

Modem Crop Protection Compounds. Edited by W. Kramer and U. Schirmer Copyright 2007 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 978-3-527-31496-6 

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Besides the bleaching cause by either carotene inhibition or peroxidation more targets for "bleaching herbicides" are conceivable, e.g., interference with chlorophyll formation itself. DTP, a substituted pyrazole, was reported to induce chlorosis by blocking... 

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