In the lycophyte Selaginella martensii is the “extra-qT” related to energy spillover? Insights into photoprotection in ancestral vascular plants

摘要: Abstract Lycophytes are early diverging vascular plants, representing a minor group as compared to the dominating euphyllophytes, mostly angiosperms. Having maximally developed in CO 2 -rich atmosphere, extant lycophytes characterized by low carbon fixing capacity, which is compensated marked ability induce non-photochemical quenching of chlorophyll fluorescence ( NPQ ). Different kinetic components contribute , particular fast relaxing high-energy qE, middle qT, and slowly qI. Unlike angiosperms, enhance qT component under high light, originating from an “extra-qT”. In this research, we analyze whether Selaginella martensii extra-qT can reflect photosystem (PS) I-based mechanism activated upon saturation qE capacity. From comparative analyses parameters, fixation, vivo low- room-temperature spectroscopy, thylakoid protein phosphorylation, it proposed that not mechanistically separate ordinary qT. The results suggest relationship between photoprotective energy spillover PSI, sensing excitation pressure inside PSII possibly facilitated phosphorylation Lhcb6, antenna PSII. Energy emphasizes 77 K emission PSI core (F714) becomes more relevant at irradiance levels corresponding -limited, potentially photoinhibiting phase photosynthesis. At highest irradiances, when Lhcb6 potential has been saturated, major LHCII increases turn its level, probably leading full exploitation safe sink. It suggested photosynthetic capacity could allow easier experimental access use quencher for PSII, debated, emerging issue about photoprotection