Autophagy is essential in the turnover of cell components. In animals, ferritinophagy,
targeting ferritins an
important way for intracellular iron mobilization. In plants, ferritins are targeting
chloroplasts and
mitochondria, whereas the majority of cellular iron is found in chloroplasts. Little
is known, however, on
the iron recycling from chloroplasts. Accumulation of ferritins under developmental
senescence has been
long described, the connection between ferritins and iron remobilization has not been
fully revealed. In
Arabidopsis thaliana Col-0 leaves iron content of chloroplasts, and the iron peak
at plastidial loci gained by
low energy X-ray fluorescence microscopy (LEXRF) indicated strong coincidences: a
peak accumulation
occurred at early senescence that disappeared in later stages. Appearance of ferritins
is, however, a rare event
found exclusively at early senescence. Expression and protein amount of of FERs also
indicated the same
pattern. In autophagosome defective (atg5.2, atg7.2, ati1) lines, iron accumulation
was revealed at plastidial
locations associated increased plastidial Fe content, FER expression and protein amount.
Although we have
no data on any co-localization of ferritins to autophagosomes, data at the current
stage suggest that
ferritinophagy might be the way of iron recycling from plastids during developmental
senescence.
This work was supported by the grant K-146865 of NKFIH, Hungary. Á.S. was supported
by the János
Bolyai Scholarship of the Hungarian Academy of Sciences (BO-00113-23-8). Instrument
center access was
financed under ReMade@ARI PIDs 27548 & 34653 (financed as part of HORIZON-INFRA-2021-SERV-
01, 101058414, 10039728 and 22.0018). We acknowledge Elettra-Sincrotrone, Trieste,
Italy for the beam
time accesses (20235332 & 20245567).
