Introduction of a terminal electron sink in chloroplasts decreases leaf cell expansion associated with higher proteasome activity and lower endoreduplication.
J Exp Bot
; 75(15): 4625-4640, 2024 Aug 12.
Article
in En
| MEDLINE
| ID: mdl-38364822
ABSTRACT
Foliar development involves successive phases of cell proliferation and expansion that determine the final leaf size, and is characterized by an early burst of reactive oxygen species generated in the photosynthetic electron transport chain (PETC). Introduction of the alternative PETC acceptor flavodoxin in tobacco chloroplasts led to a reduction in leaf size associated to lower cell expansion, without affecting cell number per leaf. Proteomic analysis showed that the biogenesis of the PETC proceeded stepwise in wild-type leaves, with accumulation of light-harvesting proteins preceding that of electron transport components, which might explain the increased energy and electron transfer to oxygen and reactive oxygen species build-up at this stage. Flavodoxin expression did not affect biogenesis of the PETC but prevented hydroperoxide formation through its function as electron sink. Mature leaves from flavodoxin-expressing plants were shown to contain higher levels of transcripts encoding components of the proteasome, a key negative modulator of organ size. Proteome profiling revealed that this differential accumulation was initiated during expansion and led to increased proteasomal activity, whereas a proteasome inhibitor reverted the flavodoxin-dependent size phenotype. Cells expressing plastid-targeted flavodoxin displayed lower endoreduplication, also associated to decreased organ size. These results provide novel insights into the regulation of leaf growth by chloroplast-generated redox signals, and highlight the potential of alternative electron shuttles to investigate the link(s) between photosynthesis and plant development.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Nicotiana
/
Chloroplasts
/
Plant Leaves
/
Proteasome Endopeptidase Complex
Language:
En
Journal:
J Exp Bot
Journal subject:
BOTANICA
Year:
2024
Type:
Article
Affiliation country:
Argentina