Mitochondrial PPR-containing proteins are essential to sustain embryo development in Arabidopsis thaliana

MARCHETTI, MARIA FERNANDA; CORDOBA JUAN PABLO; MIZUKI, TAKENAKA; BRENNICKE AXEL; PAGNUSSAT G; EDUARDO JULIAN ZABALETA

Berlin

Congreso; XVII Annual Meeting of the International Society of Endocytobiology; 2015

International Society of Endocytobiology

PPRs containing proteins are characterized by a motif of a degenerate 35 amino acid repeat. Most PPRs proteins are specific RNA-binding proteins which are involved in RNA processing, including editing, maturation, stability, and translation. We focused on the role of PPR proteins potentially involved in embryo development. Four T-DNA insertion mutants encoding for three PPR proteins (At2g02150, At1g79490 and At3g29290) were analyzed. These mutants showed ~25% of shriveled seeds in mature siliques, which do not germinate not even in MS sucrose medium, suggesting embryo lethality. Transient transformation with these PPR proteins fused to GFP showed they are localized in mitochondria. As we were unable to obtain homozygous mutant plants, silencing assays were developed with two independent artificial microRNAs for each gene. We obtained plants in which ~70% of gene expression was silenced and mature siliques of these plants were preliminary analyzed. Most siliques were short length and contained aborted embryos. To further investigate this phenotype, we examined female and male gametophyte development. Apparently, embryo sac proceeded normally but anthers maturation did not, showing that pollen grains remained stuck inside anthers and pollination could not progress. We are now interested in potential targets of these PPR proteins. All together, these results suggest that the expression of these mitochondrial PPR genes is essential to sustain embryo development and the proteins encoded may alter anther maturation and consequently affect fertilization in Arabidopsis thaliana.