Functional analysis of Arabidopsis thaliana pollen aquaporin genes.

JORGE PROMETEO MUSCHIETTI

Shanghai, China.

Conferencia; Pollen Biology International Symposium/Workshop. ?Frontiers in Pollen Tube Biology; 2012

Shanghai Institute of Plant Physiology and Ecology, CAS

Reproduction in flowering plants includes pollen germination and pollen tube elongation, where water and/or solutes movements must be finely regulated. These regulations suggest the participation of aquaporins mediating water and/or solutes transport. We identified TIP5;1 and TIP1;3 as Arabidopsis aquaporin genes that are selectively and highly expressed in mature pollen. They can transport both water and urea when expressed in Xenopus oocytes (Soto, FEBS Letter 2008, 582). The water transport activity of TIP5;1 is regulated by pH. We found that GFP?TIP5;1 is located in the mitochondria of pollen tubes. The single mutants tip1;3 and tip5;1 and the tip1;3 tip5;1 double mutant, are fertile, but all mutants had shorter pollen tubes when germinated in vitro in the absence of exogenous nitrogen (Soto, The Plant Journal, 2010,1038). We also characterized NIP4;1 y NIP4;2, the other two Arabidopsis aquaporin genes that are selectively expressed in mature pollen and in pollen tubes. NIP4;1 y NIP4;2 are two genes with high DNA sequence identity (88%) only separated by ~2,5 kb. We found that while NIP4;1 showed low levels of expression in mature pollen, NIP4;2 is highly and specifically expressed in pollen tubes.