Abstract Detail



Physiology

COLPO, ANDREA [1], Pancaldi, Simonetta [1], Ferroni, Lorenzo [2].

Quantification of Photosystem II photoprotection in Selaginella martensii Spring (Lycopodiophyta) acclimated to different light regimes.

Lycophytes are a well-known group of early divergent vascular plants predominant in the Carboniferous geological period (ca. 425 million years ago). Since then, most Lycophyte species have progressively become extinct and nowadays the extant species represent approximately 1% of land plants1. Among the few extant Lycophytes, Selaginella martensii is studied as a model species to investigate light energy management in ancestral tracheophytes2. In fact, although it inhabits wet and shady environments of tropical rainforest, this plant is surprisingly efficient in acclimating to extreme light regimes, such as deep shade and full sunlight without impairing its photosynthetic apparatus. This feature, uncommon among most of the pteridophytes, is reasonably allowed by specific photoprotective mechanisms, which are still unclear.
The aim of our research is to unveil photoprotective strategies that can underlie the marked ability of S. martensii to acclimate to extreme light regimes. The onset of photosystem II (PSII) photoinhibition was compared in S. martensii plants acclimated to different natural light regimes, in the hypothesis of a gradient in photoprotection capacity: extreme shade or intermediate shade or high light regimes. To this aim we used a fast and non-invasive PAM-fluorimetry method developed in the last years, which is based on the calculation of the parameter of photochemical quenching measured in the dark (qPd) from light-response curves. The analysis of qPd trend throughout the light routine was used to quantify the photoprotective component of the non-photochemical quenching parameter (pNPQ). In fact, qPd is deemed sensitive to the onset of photoinhibition. Yet, at the same time, qPd is influenced also by PSII antenna uncoupling, a process conceivably involved in photoprotection in low light-acclimated plants. Our results indicate that high light-grown plants are expectedly photoinhibited at the highest irradiances, but they are characterized by an extensive antenna uncoupling too. We also observed that the three groups of treatment, once photoinhibition has started, behave differently in response to further increasing irradiance. High light-grown and intermediate shade-grown plants simply exacerbated their photoinhibition following the increasing light intensity (monotonous decay of qPd). Surprisingly, the extreme shade-grown plants tend to stabilize their photoinhibition level (stable qPd after an irradiance threshold), suggesting that further photoprotective mechanism could occur and contrast a more severe photoinhibition.
1Pryer et al. (2004) American Journal of Botany 91(10), 1582-159
2Ferroni et al. (2016) New Phytologist, 211(2), 554-568.
3Ruban et al. (2012) BBA-Bioenergetics, 1817(7), 977-98
4Ware et al. (2015) Photosynthesis research, 126(2-3), 261-274.


1 - University of Ferrara, Life Sciences and Biotechnology, Corso Ercole I d'Este 32, Ferrara, 44121, Italy
2 - University Of Ferrara, Life Sciences And Biotechnology, C.so Ercole I D'Este, 32, Ferrara, FE, 44121, Italy

Keywords:
lycophytes
Selaginella martensii
light regime
photosynthesis
photoprotection
photoinhibition.

Presentation Type: Poster
Session: P, Physiology Posters
Location: Virtual/Virtual
Date: Wednesday, July 29th, 2020
Time: 5:00 PM Time and date to be determined
Number: PPS001
Abstract ID:376
Candidate for Awards:Physiological Section Physiological Section Li-COR Prize


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