Mitochondrial pentatricopeptide repeat (PPR)-containing proteins are essential to sustain embryogenesis in Arabidopsis thaliana

MARCHETTI, MARIA FERNANDA; CORDOBA JUAN PABLO; PAGNUSSAT G; EDUARDO JULIAN ZABALETA

Mar del Plata

Congreso; XV Congreso Latinoamericano; 2014

One of the largest gene families of the plant genome encodes proteins characterized by tandem arrays of pentatricopeptide repeats (PPRs) composed by characteristic 35 amino acid motifs. The family has greatly expanded in higher plants (450 members in Arabidopsis) but also it has been found in animal and fungal proteins. PPR proteins are sequence-specific RNA-binding proteins implicated in many aspects of RNA processing primarily in organelles. We focused on the role of PPR proteins potentially involved in embryo development. Phenotypes of four T-DNA insertion mutants for three genes encoding PPR-containing proteins (At2g02150, At1g79490 and At3g29290) were analyzed by DIC microscopy. These mutants show a delayed embryo development: siliques from heterozygous plants contain around 23% of globular to early heart stage embryos segregating from completely mature embryos. Consistent with this, we were unable to obtain homozygous mutant plants suggesting embryo lethality. Additionally, transient transformation of tobacco leaf epidermal cells showed these PPR proteins fused to GFP are localized in mitochondria. All together, these results strongly suggest that mitochondrial PPR-containing proteins encoded by genes At2g02150, At1g79490 and At3g29290 are essential to sustain embryogenesis in A. thaliana.