NIP4;1 and NIP4;2 are aquaporins specifically espressed in pollen grains and pollen tubes involved in reproduction in Arabidopsis thaliana.

JORGE MUSCHIETTI; MARÍA LAURA BARBERINI; MARTÍN MECCHIA; NICOLÁS AYUB; GABRIELA AMODEO; GABRIELA SOTO; JULIANA PEREZ

Paris

Congreso; 26th International Conference on Arabidopsis Research; 2015

International Conference on Arabidopsis Research

In Angiosperms, reproduction involves processes where water and solutes transport is regulated. In plants with dry stigmas, water and non-polar molecules are transported into pollen from the stigma. Then, additional entry allows cytosolic adjustment of ions and maintenance of turgor pressure during tip growth. Aquaporins may mediate this transport during pollen germination and/or tube growth. In Arabidopsis thaliana, only 4 aquaporin genes are expressed in mature pollen and tubes: TIP5;1, TIP1;3, NIP4;1 and NIP4;2. Here, we proposed NIP4;1 and NIP4;2 mediate water and solute transport during pollen development, germination and tube growth. They have 84% amino acidic identity, but they displayed different expression patterns. While NIP4;1 showed low expression levels in mature pollen, NIP4;2 peaked during tube growth. NIP4;1pro:GUS is active in mature pollen and pollen tubes, whereas NIP4;2pro:GUS only in pollen tubes. Simple nip4;1 and nip4;2 mutants and double amiRNA knockdowns showed distorted segregation ratios, reduced number of seeds, pollen germination rate and tube length. Lines expressing EGFP-tagged NIP4;1 and NIP4;2 under their own promoters rescued the mutant phenotypes. Fusion proteins are localized in the plasma membrane and intracellular vesicles of pollen grains and tubes. Thus, we propose that NIP4;1 and NIP4;2 are aquaporins of mature pollen and pollen tubes respectively, playing partially overlapping roles in pollen development and pollination.