THE ELECTRON SHUTTLE ADX-ADXR IS ESSENTIAL FOR GAMETOPHYTE DEVELOPMENT IN Arabidopsis thaliana

BELLIDO A; DISTEFANO A; EDUARDO JULIAN ZABALETA; PAGNUSSAT G

Rosario

Congreso; L Reuniòn Anual SAIB; 2014

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 adrenоdoxin and adrenodoxin reductase respectively. Siliques of ADXR/adxr plants presented around 30% of abortions and reciprocal crossings showed that transmission trough 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 adxr 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 a communication problem between the male and the female gametophytes. The expression pattern of ADXR indicates that its expression is specific for the maternal tissues of the ovules. Furthermore, expression is also detected in leaves and sepals, indicating that ADXR might have sporophytic functions as well