The maize pentatricopeptide repeat gene empty pericarp4 (emp4) is required for proper cellular development in vegetative tissues.
The empty pericarp4 (emp4) gene encodes a mitochondrion-targeted pentatricopeptide repeat (ppr) protein that is involved in the regulation of mitochondrial gene expression and is required for seed development. In homozygous mutant emp4-1 kernels the endosperm is drastically reduced and the embryo is retarded in its development and unable to germinate. With the aim of investigating the role of emp4 during post-germinative development, homozygous mutant seedlings were obtained by cultivation of excised immature embryos on a synthetic medium. In the mutants both germination frequency as well as the proportion of seedlings reaching the first and second leaf stages were reduced. The anatomy of the leaf blades and the root cortex was not affected by the mutation, however severe alterations such as the presence of empty cells or cells containing poorly organized organelles, were observed. Moreover both mitochondria and chloroplast functionality was impaired in the mutants. Our hypothesis is that mitochondrial impairment, the primary effect of the mutation, causes secondary effects on the development of other cellular organelles. Ultra-structural features of mutant leaf blade mesophyll cells are reminiscent of cells undergoing senescence. Interestingly, both structural and functional damage was less severe in seedlings grown in total darkness compared with those exposed to light, thus suggesting that the effects of the mutation are enhanced by the presence of light.
DISAA - Dipartimento di Scienze Agrarie e Ambientali - Produzione, Territorio, Agroenergia Università degli Studi di Milano - Via Celoria 2, 20133 Milano, Italy.
Damiano
D
Gabotti
Dipartimento di Bioscienze, Università degli Studi di Milano - Via Celoria 26, 20133 Milano, Italy.
Elisabetta
E
Caporali
DISAA - Dipartimento di Scienze Agrarie e Ambientali - Produzione, Territorio, Agroenergia Università degli Studi di Milano - Via Celoria 2, 20133 Milano, Italy.
Priscilla
P
Manzotti
DISAA - Dipartimento di Scienze Agrarie e Ambientali - Produzione, Territorio, Agroenergia Università degli Studi di Milano - Via Celoria 2, 20133 Milano, Italy.
Martina
M
Persico
DISAA - Dipartimento di Scienze Agrarie e Ambientali - Produzione, Territorio, Agroenergia Università degli Studi di Milano - Via Celoria 2, 20133 Milano, Italy.
Gianpiero
G
Vigani
DISAA - Dipartimento di Scienze Agrarie e Ambientali - Produzione, Territorio, Agroenergia Università degli Studi di Milano - Via Celoria 2, 20133 Milano, Italy. Electronic address: gabriella.consonni@unimi.it.
Gabriella
G
Consonni
D049109:Cell Proliferation / Q000528:radiation effects; D019069:Cell Respiration / Q000528:radiation effects; D048430:Cell Shape / Q000528:radiation effects; D017353:Gene Deletion; D017343:Genes, Plant; D018525:Germination / Q000528:radiation effects; D008027:Light; D008928:Mitochondria / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D009928:Organ Specificity / Q000235:genetics* / Q000528:radiation effects; D010100:Oxygen / Q000378:metabolism; D010641:Phenotype; D059828:Plant Cells / Q000528:radiation effects / Q000648:ultrastructure; D018515:Plant Leaves / Q000166:cytology / Q000528:radiation effects / Q000648:ultrastructure; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020449:Repetitive Sequences, Amino Acid; D036226:Seedlings / Q000254:growth & development / Q000528:radiation effects; D013347:Subcellular Fractions / Q000378:metabolism; D003313:Zea mays / Q000166:cytology* / Q000235:genetics* / Q000528:radiation effects / Q000648:ultrastructure
D010940:Plant Proteins; D010100:Oxygen
Empty pericarp mutants; Leaf cell ultra-structure; Mitochondria; Pentatricopeptide repeat proteins; Zea mays