
%0 Journal Article
%A Mohanty, N 
%A Gilmore, AM 
%A Yamamoto, HY 
%T Mechanism of Non-Photochemical Chlorophyll Fluorescence Quenching. II. Resolution of Rapidly Reversible Absorbance Changes at 530 Nm and Fluorescence Quenching by the Effects of Antimycin, Dibucaine and Cation Exchanger, A23187
%J Functional Plant Biology
%D 1995/04/01
%V 22
%N 2
%P 239-247
%K ATP hydrolysis, excitation energy dissipation, light-scattering changes, lumenacidification, Stern-Volmer fluorescence quenching analysis, violaxanthin de-epoxidation, xanthophyll cycle, zeaxanthin
%R https://doi.org/10.1071/PP9950239
%U https://www.publish.csiro.au/paper/PP9950239 
%X The putative relationship between the light-induced absorbance increase at 530 nm (&#916;A530), the so-called light-scattering change, and non-photochemical chlorophyll fluorescence quenching (NPQ) was examined by the effect of inhibitors. Antimycin at a low concentration (350 nM) completely inhibited fluorescence quenching while only partially inhibiting A530. This effect was independent of the mode of thylakoid energisation and preinduction of violaxanthin de-epoxidation. Dibucaine at 20 FM abolished NPQ but had little effect on &#916;A530. Moreover, the light-induced &#916;A530 signal was present even in the absence of de-epoxidised xanthophylls. The cation exchanger A23187 blocked the development of NPQ as well as relaxed fluorescence quenching at steady state without involving a major portion of &#916;A530. Thus, the relationship between energy-dependent A530 changes and fluorescence quenching was non-linear under all conditions tested. The light-induced absorbance increase at 530 nm, therefore, is insufficient for NPQ. The differential effects of inhibitors are explained schematically, depicting three phases for NPQ: (a) formation of zeaxanthin and antheraxanthin by the xanthophyll cycle; (b) formation of a state reflected by A530 that is induced by the transthylakoid ApH, possibly involving aggregation of LHCII; and (c) fluorescence quenching by the combined effect of both steps and by the H+-cation exchange properties of thylakoid membranes. 
