The mitochondrial electron shuttle ADXR-ADX is essential for gametophyte development in Arabidopsis

BELLIDO, ANDRÉS MARTÍN; DISTÉFANO, AYELÉN MARIANA; ZABALETA, EDUARDO JULIÁN; PAGNUSSAT, GABRIELA CAROLINA

Wroclaw

Conferencia; 9th International Conference for Plant Mitochondrial Biology ICPMB; 2015

In Arabidopsis, the female gametophyte is a polarized structure composed by seven cells: the egg cell, the central cell, two synergids and three antipodal cells. We here show the study of Arabidopsis mutants with insertions in ADX or ADXR, which are nuclear genes encoding for mitochondrial adredodoxin and adrenodoxin reductase, respectively. Siliques of ADXR/adxr plants presented around 40% of abortions and reciprocal crossings showed that transmission through the female gametophyte is severely compromised. DIC studies revealed mutant gametophytes with abnormal cell morphologies that are not able to reach complete maturation. The identity of all cells inside adrx embryo sacs was analyzed by studying the expression of cell specific markers for egg cell, central cell, antipodal and synergid cells. The results of anilin blue staining assays and pollination using the pollen tube marker pLAT52-RFP line as a pollen donor, suggest that attraction of pollen tubes is impaired in mutant embryo sacs. Pollen tubes showed abnormal growing patterns, including invading embryo sacs, which suggest the communication between the male and the female gametophyte is impaired. The expression pattern of ADRX indicates that its expression is specific for the maternal tissues of the ovules. Two hybrid assays and BiFC experiments identified mitochondrial interactors for ADX that are related to several metabolic pathways.