Hierarchy amongst photosynthetic acclimation responses for plant fitness

Abstract

We have compared the seed production of Arabidopsis wild‐type and mutant plants impaired in the regulation of the photosynthetic light reactions grown under natural conditions in the field. Mutant plants (npq4) lacking feedback de‐excitation were, as previously demonstrated, severely affected in seed production. Seed sets of plants deficient in state transitions (stn7) were 19% smaller than those of wild‐type plants, whereas plants missing the STN8 kinase required for the phosphorylation of the core photosystem II reaction centre polypeptides (stn8) had a normal seed production. Plants lacking both STN7 and STN8 kinases were strongly affected, indicating that these mutations act synergistically. In contrast, npq4×stn7 double mutants had the same seed set as npq4 mutants.

ArabidopsisSTN7 Kinase Provides a Link between Short- and Long-Term Photosynthetic Acclimation

“…In flowering plants, however, the physiological significance of state transitions is less clear because their mobile LHCII pools are significantly smaller than those in green algae (Allen, 1992;Delosme et al, 1994). Moreover, plant development and fitness are only marginally affected in A. thaliana mutants impaired in state transitions (Lunde et al, 2000;Bonardi et al, 2005;Tikkanen et al, 2006), even under fluctuating light (Bellafiore et al, 2005) or field conditions (Frenkel et al, 2007) when the ability to adapt to illumination changes should become crucial. Therefore, it has been speculated that state transitions play a less prominent role in land plants than in green algae (Finazzi et al, 2002;Finazzi, 2005), becoming important only under low light conditions (Tikkanen et al, 2006).…”

Fluorescence as a Tool to Understand Changes in Photosynthetic Electron Flow Regulation

“…The interpretation of qE is possibly the most complex of the NPQ components, as it is linked to faster regulation of photosynthesis than qT and qI with most organisms, especially under naturally fluctuating environment (Lavaud 2007). Frenkel et al (2007) demonstrated that qE is critical for maintaining the fitness of plants under natural temperate-light conditions, rather than qT. Also, in cyanobacteria and green microalgae, qT has no significant physiological importance in photoprotection towards high-light stress, yet is more relevant in low light conditions (Mullineaux and Emlyn-Jones 2005;Ruban and Johnson 2009) and for acclimation to different light quality (Pfannschmidt 2005).…”

Phosphorylation of the Lhcb2 isoform of Light Harvesting Complex II is central to state transitions

“…Only a relatively small fraction of the LHCII antenna (,20%) is estimated to participate in state transitions in Arabidopsis (Arabidopsis thaliana; Allen, 1992). However, the process is conserved across the green eukaryotes and is relevant to plant fitness (Frenkel et al, 2007). Under high light, energy-dependent quenching of LHCII predominates, and furthermore, this antenna can uncouple from PSII (Wientjes et al, 2013b).…”