Plant photosynthetic pigments: Methods and tricks for correct quantification and identification

Abstract

Chloroplast of green photosynthetic tissues in the Viridiplantae (monophyletic group that includes green algae and terrestrial plants) is characterised by a relatively conserved composition of pigments (Esteban et al. 2015). Leaves of virtually all plant species invariably contain chlorophyll (Chl) a and Chl b, and six carotenoids. Five of them are xanthophylls (carotenoids that contain oxygen): neoxanthin (Neo), lutein (Lut), violaxanthin (Vio), antheraxanthin (Ant) and zeaxanthin (Zea). The remaining carotenoid is a carotene (no oxygen in the molecule): Β-carotene (Β-Car). Additionally, certain taxa contain a second carotene: a-Car, which partially substitutes Β-Car in some species under low light environment (Young and Britton 1989; Esteban and García-Plazaola 2016). Some species phylogenetically unrelated also include lutein epoxide (Lx), a xanthophyll likewise related to shade acclimation (Matsubara et al. 2005; Esteban et al. 2009b). Regarding pigment concentration, in agreement with the relatively conserved composition of pigments across green photosynthetic organisms, and because the maximum Chl concentration per leaf is limited by specific and physiological constrains (Niinemets 2007), photosynthetic pigments are restricted within specific ranges of concentrations. Highly reliable ranges of pigment content for non-stressed plants that were obtained from two data-bases comprising more than 800 species can be found in (Esteban et al. 2015; Fernández-Marín et al. 2017) (summarized as reference in Table 3.1).