Pollen-specific aquaporins NIP4;1 and NIP4;2 are required for pollen development and pollination in Arabidopsis thaliana

JULIANA PEREZ; PATRICK BIENERT ; AYUB, NICOLAS; YANEFF AGUSTIN; BARBERINI, MARIA LAURA; MECCHIA, MARTIN; AMODEO, GABRIELA; SOTO, GABRIELA; MUSCHIETTI, JORGE

PLANT CELL

AMER SOC PLANT BIOLOGISTS

Lugar: Rockville; Año: 2016

1040-4651

In flowers with dry stigmas, pollen development, pollination and pollen tube growth58 require spatial and temporal regulation of water and nutrient transport. To better understand59 the molecular mechanisms involved in reproductive processes, we characterized NIP4;160 and NIP4;2, two pollen-specific aquaporins (AQPs) of Arabidopsis thaliana. NIP4;1 and61 NIP4;2 are paralogs found exclusively in the angiosperm lineage. Although they have 84%62 amino acid identity, they displayed different expression patterns. NIP4;1 has low63 expression levels in mature pollen, while NIP4;2 expression peaks during pollen tube64 growth. Additionally, NIP4;1pro:GUS flowers showed GUS activity in mature pollen and65 pollen tubes, whereas NIP4;2pro:GUS flowers only in pollen tubes. Single T-DNA mutants66 and double amiRNA knockdowns had fewer seeds per silique and reduced pollen67 germination and pollen tube length. Survival assays in oocytes showed NIP4;1 and NIP4;268 function as water and non-ionic channels. We also found that NIP4;1 and NIP4;2 C-termini69 are phosphorylated by a pollen-specific CPK that modifies their water permeability.70 Transport assays in yeast indicated that NIP4;1 also transports ammonia, urea, boric acid71 and H2O2. Thus, we propose that aquaporins NIP4;1 and NIP4;2 are exclusive components72 of the reproductive apparatus of angiosperms with partially redundant roles in pollen73 development and pollination.