Photosystem II organisation in chloroplasts of Arum italicum leaf depends on tissue location

Abstract

The growth of plants under stable light quality induces long-term acclimation responses of the photosynthetic apparatus. Light can even cause variations depending on the tissue location, as in Arum italicum leaf, where chloroplasts are developed in the lamina and in the entire thickness of the petiole. We addressed the question whether differences in plastids can be characterised in terms of protein-protein interactions in the thylakoid membranes. Thylakoid assembly was studied in the palisade and spongy tissue of the lamina and in the outer parenchyma and inner aerenchyma of the petiole of the mature winter leaf of Arum italicum. The chlorophyll-protein complexes were analysed by means of blue-native-PAGE and fluorescence emission spectra. The petiole chloroplasts differ from those in the lamina in thylakoid composition: (1) reaction centres are scarce, especially photosystem (PS) I in the inner aerenchyma; (2) light-harvesting complex (LHC) II is abundant, (3) the relative amount of LHCII trimers increases, but this is not accompanied by increased levels of PSII-LHCII supercomplexes. Nevertheless, the intrinsic PSII functionality is comparable in all tissues. In Arum italicum leaf, the gradient in thylakoid organisation, which occurs from the palisade tissue to the inner aerenchyma of the petiole, is typical for photosynthetic acclimation to low-light intensity with a high enrichment of far-red light. The results obtained demonstrate a high plasticity of chloroplasts even in an individual plant. The mutual interaction of thylakoid protein complexes is discussed in relation to the photosynthetic efficiency of the leaf parts and to the ecodevelopmental role of light.

Light‐dependent reversible phosphorylation of the minor photosystem II antenna Lhcb6 (CP24) occurs in lycophytes

“…J€ arvi et al, 2011). For instance, its shade acclimation is responsible for a low amount of LHCII-PSII super-complexes (Sc1), but abundant free LHCII trimers, in line with the results obtained in Arum italicum by Pantaleoni et al (2009) and in low light-adapted Arabidopsis by Kou ril et al (2013). More interesting is the presence of super-complexes Sc2 (PSI-LHCI-LHCII) and Sc3 (PSI-LHCI-LHCII-PSII).…”

“…Thylakoid membranes were isolated as described previously (Pantaleoni et al, 2009) in the presence of 10 mM NaF to inhibit thylakoid protein dephosphorylation (Rintam€ aki et al, 2000). Thylakoids were rapidly frozen in liquid nitrogen and stored at À80°C.…”

Frequently asked questions about chlorophyll fluorescence, the sequel

“…Conversely, release of LHCII trimers enhances F680. There are several lines of evidence linking F680 to free LHCII, among which LHCII release from grana cores induced by thylakoid unstacking (van der Weij-de Wit et al 2007), LHCII release from grana margins induced by digitonin treatment of isolated thylakoids (Grieco et al 2015), and also steady-state conditions in which LHCII trimers are overly abundant as compared to photosystem cores (Pantaleoni et al 2009; Ferroni et al 2013). Native LHCII trimers have a strong tendency to aggregate in vitro, leading to the appearance of a new long-wavelength band, F700, also accompanied by a quenching of fluorescence, which could support a role of LHCII aggregates in excess energy dissipation (Mullet et al 1980; Ruban and Horton 1992; Karapetyan 2004; Schaller et al 2011).…”

“…Different factors such as senescence (Wingler et al 2005), injury/wounding (Quilliam et al 2006), microbial infection (Scharte et al 2005; Bonfig et al 2006; Berger et al 2007), leaf water status (Meyer and Genty 1999; Nejad et al 2006), photosynthetic induction (Meyer and Genty 1999), spatial gradients in thylakoid differentiation (Pantaleoni et al 2009), chilling (Hogewoning and Harbinson 2007) and ozone exposure (Leipner et al 2001) can cause photosynthetic heterogeneity. This type of photosynthetic heterogeneity is difficult to capture with non-imaging fluorescence techniques.…”

Photosynthetic Acclimation to the Light Environment: Molecular Mechanisms to Understand Plant Consortia

“…This has proven to be a powerful approach for the analysis of diurnal and seasonal variations in photosynthetic parameters [22] and can as well be profitably applied to characterize vertical patterns, i.e. the expression of LTRs, including different species, different leaves of a single species, up to different portions of the same leaf [23][24][25][26][27]. Nevertheless, evaluations about the impact of light on a vertical pattern of plant species should also take into account that each pattern is also the result of a range of interactions of plants with their environment, thus not only light, but water, nutrients, temperature, biotic interactions.…”