Expression of the minor isoform pea ferredoxin in tobacco alters photosynthetic electron partitioning and enhances cyclic electron flow.
Ferredoxins (Fds) are ferrosulfoproteins that function as low-potential electron carriers in plants. The Fd family is composed of several isoforms that share high sequence homology but differ in functional characteristics. In leaves, at least two isoforms conduct linear and cyclic photosynthetic electron transport around photosystem I, and mounting evidence suggests the existence of at least partial division of duties between these isoforms. To evaluate the contribution of different kinds of Fds to the control of electron fluxes along the photosynthetic electron transport chain, we overexpressed a minor pea (Pisum sativum) Fd isoform (PsFd1) in tobacco (Nicotiana tabacum) plants. The transplastomic OeFd1 plants exhibited variegated leaves and retarded growth and developmental rates. Photosynthetic studies of these plants indicated a reduction in carbon dioxide assimilation rates, photosystem II photochemistry, and linear electron flow. However, the plants showed an increase in nonphotochemical quenching, better control of excitation pressure at photosystem II, and no evidence of photoinhibition, implying a better dynamic regulation to remove excess energy from the photosynthetic electron transport chain. Finally, analysis of P700 redox status during illumination confirmed that the minor pea Fd isoform promotes enhanced cyclic flow around photosystem I. The two novel features of this work are: (1) that Fd levels achieved in transplastomic plants promote an alternative electron partitioning even under greenhouse light growth conditions, a situation that is exacerbated at higher light intensity measurements; and (2) that an alternative, minor Fd isoform has been overexpressed in plants, giving new evidence of labor division among Fd isoforms.
Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE 901 87 Umea, Sweden. nicolas.blanco@plantphys.umu.se
Nicolás E
NE
Blanco
Romina D
RD
Ceccoli
María V Dalla
MV
Vía
Ingo
I
Voss
María E
ME
Segretin
Fernando F
FF
Bravo-Almonacid
Michael
M
Melzer
Mohammad-Reza
MR
Hajirezaei
Renate
R
Scheibe
Guy T
GT
Hanke
D002245:Carbon Dioxide / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism; D004579:Electron Transport / Q000235:genetics / Q000528:radiation effects; D005288:Ferredoxins / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D005470:Fluorometry; D018506:Gene Expression Regulation, Plant; D015151:Immunoblotting; D008027:Light; D046529:Microscopy, Electron, Transmission; D018532:Pisum sativum / Q000235:genetics* / Q000378:metabolism; D010788:Photosynthesis / Q000235:genetics* / Q000528:radiation effects; D045331:Photosystem I Protein Complex / Q000235:genetics / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000235:genetics / Q000378:metabolism; D010802:Phylogeny; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D010940:Plant Proteins / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D020033:Protein Isoforms / Q000145:classification / Q000235:genetics / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics* / Q000378:metabolism
D005288:Ferredoxins; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D020033:Protein Isoforms; D002734:Chlorophyll; D002245:Carbon Dioxide; C001785:chlorophyll P 700