A mitochondrial ADX-ADXR-P450 shuttle is essential for gametophytic development in A. thaliana

SETZES N, DISTEFANO A, BELLIDO A, FIOL DF, ZABALETA E, PAGNUSSAT GC.

Córdoba

Congreso; XXXII Reunión Argentina de Fisiología Vegetal (RAFV) y XVI Congreso Latinoamericano de Fisiología Vegetal .; 2018

In plants, gametes are specified in the haploid gametophytes,which makes them essential for sexual reproduction.We have identified and studied Arabidopsismutants with an insertion in a nuclear gene encodingfor a mitochondrial adrenodoxin reductase (ADXR) thathave female gametophyte development defects. Inmammals and insects mitochondria, adrenodoxin (ADX)mediates electron transfer from NADPH via ADXR towardsa cytochrome P450 (P450), which constitutes thefirst step in steroid hormones synthesis. Through Y2Hstudies and bimolecular fluorescence complementationassays, we have established that four ArabidopsisP450s (CYP711A1, CYP90A1, CYP75B1, CYP71B9) interactwith ADX1. We demonstrated that these P450shave mitochondrial localization by co-localization experimentsin N. benthamiana. However, knockout mutantlines for these P450s do not show gametophyticdefects. Since this could be due to functional redundancy,we performed crossings to obtain double mutantsand found that the double hemizygous mutantfor CYP711A1 and CYP90A1 showed 25% of abortedseeds, suggesting a gametophytic defect. The analysisof its embryo sacs under DIC microscopy showed developmentdefects similar to those found in ADXR mutants.In addition, the expression patterns for bothP450s were studied by using transgenic reporter lineswith GFP and/or GUS.