Digital.CSIC. Repositorio Institucional del CSIC

oai:digital.csic.es:10261/351834

Supplemental Figure S1. Characterization of 35S:FBN6-RFP lines.-- Supplemental Table S1. Primers used in this work.-- Supplemental Table S2. Phytoene levels in control and NFZ-treated N. benthamiana leaves agroinfiltrated with FBN6 and/or PSY constructs.-- Supplemental Table S3. Photosynthetic pigment levels in N. benthamiana leaves agroinfiltrated with FBN6, PSY, and/or crtB constructs.-- Supplemental Table S4. Photosynthetic pigment levels in etiolated and de-etiolating WT and fbn6 Arabidopsis seedlings.-- Supplemental Table S5. Photosynthetic pigment levels in WT and fbn6 Arabidopsis seedlings exposed to HL., Carotenoids are health-promoting plastidial isoprenoids with essential functions in plants as photoprotectants and photosynthetic pigments in chloroplasts. They also accumulate in specialized plastids named chromoplasts, providing color to non-photosynthetic tissues such as flower petals and ripe fruit. Carotenoid accumulation in chromoplasts requires specialized structures and proteins such as fibrillins (FBNs). The FBN family includes structural components of carotenoid sequestering structures in chromoplasts and members with metabolic roles in chloroplasts and other plastid types. However, the association of FBNs with carotenoids in plastids other than chromoplasts has remained unexplored. Here, we show that Arabidopsis (Arabidopsis thaliana) FBN6 interacts with phytoene synthase (PSY), the first enzyme of the carotenoid pathway. FBN6, but not FBN4 (a FBN that does not interact with PSY), enhances the activity of plant PSY (but not of the bacterial PSY crtB) in Escherichia coli cells. Overexpression of FBN6 in Nicotiana benthamiana leaves results in a higher production of phytoene, the product of PSY activity, whereas loss of FBN6 activity in Arabidopsis mutants dramatically reduces the production of carotenoids during seedling de-etiolation and after exposure to high light. Our work hence demonstrates that FBNs promote not only the accumulation of carotenoids in chromoplasts but also their biosynthesis in chloroplasts., This work was funded by grants from Spanish MCIN/AEI/10.13039/501100011033 and European NextGeneration EU/PRTR and PRIMA programs to M.R.-C. (PID2020-115810GB-I00 and UToPIQ-PCI2021-121941). M.R.-C. is also supported by Generalitat Valenciana (PROMETEU/2021/056 and AGROALNEXT/2022/067). Our group is a member of CaRed (Spanish Carotenoid Network) funded by MCIN/AEI (RED2022-134577-T). A.I.-S. and J.N.-C. received predoctoral fellowships from MCIN/AEI (PRE2018-083610 and PRE2021-098681, respectively)., Peer reviewed