Knock-out of ferritin AtFer1 causes earlier onset of age-dependent leaf senescence in Arabidopsis.
Ferritins are iron-storage proteins involved in the regulation of free iron levels in the cells. Arabidopsis thaliana AtFer1 ferritin, one of the best characterized plant ferritin isoforms to date, strongly accumulates upon treatment with excess iron, via a nitric oxide-mediated pathway. However other environmental factors, such as exposure to oxidative stress or to pathogen attack, as well as developmental factors regulate AtFer1 transcript levels. In particular, recent findings have highlighted an accumulation of the ferritin transcript during senescence. To investigate the physiological relevance of AtFer1 ferritin during senescence we isolated an Arabidopsis mutant knock-out in the AtFer1 gene, which we named atfer1-2. We analyzed it together with a second, independent AtFer1 KO mutant, the atfer1-1 mutant. Interestingly, both atfer1-1 and atfer1-2 mutants show symptoms of accelerated natural senescence; the precocious leaf yellowing is accompanied by accelerated decrease of maximal photochemical efficiency and chlorophyll degradation. However, no accelerated senescence upon dark treatment was observed in the atfer1 mutants with respect to their wt. These results suggest that AtFer1 ferritin isoform is functionally involved in events leading to the onset of age-dependent senescence in Arabidopsis and that its iron-detoxification function during senescence is required when reactive oxygen species accumulate.
Murgia
Irene
I
Sezione di Fisiologia e Biochimica delle Piante, Dipartimento di Biologia, Università degli Studi di Milano, via Celoria 26, 20133 Milan, Italy. irene.murgia@unimi.it
Vazzola
Valentina
V
Tarantino
Delia
D
Cellier
Françoise
F
Ravet
Karl
K
Briat
Jean-Francois
JF
Soave
Carlo
C
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D005293:Ferritins / Q000235:genetics / Q000378:metabolism*; D018390:Gene Targeting; D017343:Genes, Plant; D007501:Iron / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D018515:Plant Leaves / Q000254:growth & development / Q000378:metabolism; D013997:Time Factors
D029681:Arabidopsis Proteins; D017931:DNA Primers; D018744:DNA, Plant; D005293:Ferritins; D007501:Iron