AUTHOR=Ware Maxwell A. , Dall’Osto Luca , Ruban Alexander V. 

TITLE=An In Vivo Quantitative Comparison of Photoprotection in Arabidopsis Xanthophyll Mutants

JOURNAL=Frontiers in Plant Science

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2016.00841

DOI=10.3389/fpls.2016.00841

ISSN=1664-462X

ABSTRACT=<p>Contribution of different LHCII antenna carotenoids to protective NPQ (pNPQ) were tested using a range of xanthophyll biosynthesis mutants of <italic>Arabidopsis</italic>: plants were either devoid of lutein (<italic>lut2</italic>), violaxanthin (<italic>npq2</italic>), or synthesized a single xanthophyll species, namely violaxanthin (<italic>aba4npq1lut2</italic>), zeaxanthin (<italic>npq2lut2</italic>), or lutein (<italic>chy1chy2lut5</italic>). A novel pulse amplitude modulated (PAM) fluorescence analysis procedure, that used a gradually increasing actinic light intensity, allowed the efficiency of pNPQ to be tested using the photochemical quenching (qP) parameter measured in the dark (qP<sub>d</sub>). Furthermore, the yield of photosystem II (ΦPSII) was calculated, and the light intensity which induces photoinhibition in 50% of leaves for each mutant was ascertained. Photoprotective capacities of each xanthophyll were quantified, taking into account chlorophyll <italic>a/b</italic> ratios and excitation pressure. Here, light tolerance, pNPQ capacity, and ΦPSII were highest in wild type plants. Of the carotenoid mutants, <italic>lut2</italic> (lutein-deficient) plants had the highest light tolerance, and the joint the highest ΦPSII with violaxanthin only plants. We conclude that all studied mutants possess pNPQ and a more complete composition of xanthophylls in their natural binding sites is the most important factor governing photoprotection, rather than any one specific xanthophyll suggesting a strong structural effect of the molecules upon the LHCII antenna organization and discuss the results significance for future crop development.</p>