Journées de restitution 2017 PEPS Exo Mod

LEMNAMASS - Bases moléculaires de l’efficacité de la photosynthèse chez Lemnoideae, un nouveau modèle de biomasse

Pr Gilles Comte, Responsable du Centre d'Etude des Substances Naturelles, UMR 5557 CNRS-Université de Lyon, Ecologie Microbienne, Faculté de Sciences - Université de Lyon. Pr Thomas Pfannschmidt: Laboratoire de Physiologie Cellulaire et Végétale (LPCV) Team 7: Nucleo-plastidic Interaction – Chloroplast biogenesis and redox control Univ. Grenoble-Alpes / CNRS (UMR5168) / INRA (USC1359) / CEA GRENOBLE The problem

Historic development of world population

Zhu, Long, Ort 2010 Annu Rev Plant One possible solution : Improvement of photosynthesis

Zhu, Long, Ort 2010 Annu Rev Plant One possible solution : Improvement of photosynthesis

Zhu, Long, Ort 2010 Annu Rev Plant Science. 2016 Nov 18;354(6314):857-861. Improving photosynthesis and crop productivity by accelerating recovery from photoprotection. Kromdijk J1, Głowacka K2,3, Leonelli L4, Gabilly ST4, Iwai M4,5, Niyogi KK6,5, Long SP2,7. Author information Abstract Crop leaves in full sunlight dissipate damaging excess absorbed light energy as heat. When sunlit leaves are shaded by clouds or other leaves, this protective dissipation continues for many minutes and reduces photosynthesis. Calculations have shown that this could cost field crops up to 20% of their potential yield. Here, we describe the bioengineering of an accelerated response to natural shading events in Nicotiana (tobacco), resulting in increased leaf carbon dioxide uptake and plant dry matter productivity by about 15% in fluctuating light. Because the photoprotective mechanism that has been altered is common to all flowering plants and crops, the findings provide proof of concept for a route to obtaining a sustainable increase in productivity for food crops and a much-needed yield jump. The photosynthetic apparatus Structure and Function of Chloroplasts

Photosynthesis Reduction of sulfur and nitrogen Biosynthesis of -vitamins -aminoacids -lipids Highly complex -secondary thylakoid membrane metabolites system

2500 – 3000 proteins (50 plastid-encoded) Photosystem II structure

Allen and Forsberg (2001), Trends Plant Sci. PSII can be remodelled

Dekker and Boekema 2005 BBA

Dietzel et al. 2011 Plant Cell Redox control of photosystem II structure

Iwai et al. 2008 Plant Cell Redox control of photosystem II structure

Dietzel et al. 2011 Plant Cell Plant populations contain strong light gradients

PAR FR Spectrum

400000

300000 2.5 m; ~ 1000 µE 200000

100000

High light stress intensity Light 2.2 m; ~ 200 µE 0 298 344 386 425 464 501 538 575 612 648 685 721 756 792 Wavelength / nm

1.5 m; ~ 50 µE Spectrum

100000 Low light stress 80000 60000

40000

20000 Light intensity Light 0.2 m; ~ 20 µE 0 298 344 386 425 464 501 538 575 612 648 685 721 756 792 Wavelength / nm Light gradients in dense plant populations

Wagner et al. 2006, BioForum Ort et al. 2015 Re-building nature in the lab A light system that mimicks light quality gradients

PSII-Light PSI-Light Excitation imbalances between the photosystems induce redox signals

PSII-light PSI-light

PSII e- Cyt PSI PSII Cyt e- PSI PQH2 bf PQ bf Chlorophyll fluorescence as indicator for acclimation

PSI

Bonardi et al. (2005) Nature 437 PSII

Fs/Fm

Top

Middle

Bottom

0 0,02 0,04 0,06 0,08 0,1 0,12

Wagner et al. (2008) Planta 228 Steiner et al. (2009) Mol. Plant. 2 Light gradients: Adaptation vs. non-adaptation.

Strong 3D structure – Simple 2D structure – High leaf area index (LAI) Low leaf area index (LAI)

PSII must be LAI: 8-15 LAI: 1 adaptable to all positions in the PSII can be plant stand: optimized to

light harvesting optimisation to and photo- light harvesting protection at and photo- the same time protection is spatially separated A candidate for 2D photosynthesis - duckweeds

Natural conditions Phylogenetic tree Wolffia arrhiza

Spirodela polyrhiza Lemna minor

Advantages of duckweeds

Biology - The smallest flowering plants - Multiply by vegetative budding - Occur ubiquitiously in all sweet waters on Earth

Biotechnology - Exponential growth (biomass doubling in 48 hours) - Phytoremediation of municipal wastewater - Removal of algae blooms in eutrophic lakes - Biomass can be used for feeding cattle or bioethanol - EU ISO norm for heavy metal intoxication of water

Experimental biology - Spirodela genome sequenced 2014 - Easy cultivation - „Forgotten“ model of photosynthesis research Tripling biomass in six days Easy to culture and harvest Light acclimation in duckweeds

WL

PSI PSI-II

PSII PSII-I Lemna minor chlorophyll fluorescence parameters, starch and Chl accumulation.

Lemna minor two-dimensional Chl fluorescence. Differences in thylakoid membrane proteins.

A B kDa kDa 75 150 50 PSI-A 75 75 75 * C kDa 150 50 * ATPase 50 75 37 50 * 50 * P-core 25 37 CP43 37

* 20 * 37 25 P-LHCII Coomassie Cytf 20

25 Phospho-Immuno-blot 25 D1

25 LHCII

PSII supercomplex remodelling in Lemna differs from that in Arabidopsis.

Lemna Arabidopsis

PSII megacomplex PSII supercomplexes PSI, PSII dimer, * * ATP synthase PSII monomers Cyt b6f LHCII trimers * * LHCII monomers 2D BN PAGE Arabidopsis

kDa

250

150

100 PsaA/B 75

50 AtpA/B CP47 37 P-CP43 CP43 * * D2 25 D1 LHCII

PSI/Cyt SUs

PSII PSII – PSI 2D BN PAGE Lemna

kDa 250

150

100 PsaA/B 75

50 AtpA/B CP47 37 CP43 D2 25 D1 LHCII

PSI/Cyt SUs

PSII PSII-I 3 d AtpA/B

CP47

CP43

D2 D1 LHCII

PSI/

Cyt SUs

Lemna Arabidopsis Differences in Lemna photosynthesis apparatus

1. Lack of state transitions 2. No redox dependent PSII remodelling 4. CP43 / Cytf size variation (post-translational modifications?) 3. Specific changes in LHCII and CP43 phosphorylation 5. Novel subunit in PSII super-complexes? 6. Missing small subunits of PSI 7. Additional PSII super-complex Ecological adaptation of Lemna photosynthesis

1. 2D photosynthesis does not require light quality acclimation (Lack of competition for light?) 2. 2D photosynthesis has adapted specific proteins in size and phosphorylation state (reason for 1.?) 3. 2D photosynthesis may have generated novel PSII structures (optimization of light harvesting?)

4. 2D photosynthesis may have eliminated PSI subunits (acceleration of electron flow?) INRA

Equipe 7 Nucleo-plastidic interaction

Chloroplast biogenesis and redox control LEMNAMASS: PEPS ExoMod 2016 Robert Blanvillain Collaborators:

Fabien Chevalier Gilles Comte Florence Courtois Laurent Legendre Björn Grübler Marjolaine Rey Elisabeth Hommel Silva Lerbs-Mache Monique Liebers

Livia Merendino Thomas Pfannschmidt

Research Funding: Unit 804 AGIR2015