Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES New Phytologist 58-65 Arabidopsis calcium mitochondrial calcium uniporter (MCU) plant reproduction pollen tube tip-growth 2018 fdi:010073675 ENG New Phytologist 0028-646X ISI:000434153200012 1 10.1111/nph.15189 https://www.documentation.ird.fr/hor/fdi:010073675 https://www.documentation.ird.fr/intranet/publi/2018/08/010073675.pdf 219 Horizon (IRD) The mitochondrial calcium uniporter complex (MCUc) was recently characterized in details in metazoans and consists of pore-forming units (MCUs) and regulatory factors that channel calcium (Ca2+) ion into the mitochondria. MCUs participate in many stress and developmentally related processes involving Ca2+. Although multiple homologues of MCUs and one regulatory subunit are usually present in plants, the first functional characterization and contribution to Ca2+ related processes of these proteins have been reported recently. Here, we focused on two predicted Arabidopsis MCUs and studied their role in the germination and the growth of pollen tube, a tip-growing cell type highly dependent on Ca2+ homeostasis. Heterologous expression of MCU1 or MCU2 in yeast is sufficient to generate a mitochondrial Ca2+ influx. MCU1 and MCU2 fluorescent reporters are co-expressed in the vegetative cell mitochondria of the pollen grain but are undetectable in the embryo sac. We demonstrate that MCU1 and MCU2 can form a heterotypic complex. Phenotypic analyses revealed an impaired pollen tube germination and growth in vitro only for the mcu2 mutants suggesting a predominant role of MCU2. Our results show that mitochondrial Ca2+ controlled by MCUs is an additional player in Arabidopsis pollen tube germination and growth. 076 ; 020 UR232