AtTIP1;3 and AtTIP5;1, the only highly expressed Arabidopsis pollen‐specific aquaporins, transport water and urea

Abstract

Pollination includes processes where water and/or solute movements must be finely regulated, suggesting participation of aquaporins. Using information available from different transcriptional profilings of Arabidopsis thaliana mature pollen, we showed that the only aquaporins that are selectively and highly expressed in mature pollen are two TIPs: AtTIP1;3 and AtTIP5;1. Pollen exhibited a lower number and more exclusive type of aquaporin expressed genes when compared to other single cell transcriptional profilings. When characterized using Xenopus oocyte swelling assays, AtTIP1;3 and AtTIP5;1 showed intermediate water permeabilities. Although they displayed neither glycerol nor boric acid permeability they both transported urea. In conclusion, these results suggest a function for AtTIP1;3 and AtTIP5;1 as specific water and urea channels in Arabidopsis pollen.

The R2R3 MYB Transcription Factor DUO1 Activates a Male Germline-Specific Regulon Essential for Sperm Cell Differentiation inArabidopsis

“…TIP5;1 is involved in the transport of water and urea (Vander Willigen et al, 2006;Soto et al, 2008) as well as of boron in seedlings (Pang et al, 2010). TIP5;1 localizes to mitochondria, and tip5;1 pollen tubes grow shorter in the absence of exogenous nitrogen (Soto et al, 2010).…”

Tonoplast Aquaporins Facilitate Lateral Root Emergence

“…TIP1 and TIP2 isoforms are largely expressed in vegetative tissues and are thought to be preferentially associated with the large lytic vacuoles and vacuoles accumulating vegetative storage proteins, respectively (Jauh et al, 1998). TIP3s are expressed in seeds (Vander Willigen et al, 2006;Hunter et al, 2007;Frigerio et al, 2008), and TIP5;1 is exclusively expressed in dry seeds and pollen grains (Vander Willigen et al, 2006;Soto et al, 2008;Wudick et al, 2014).…”

Aquaporins as targets for stress tolerance in plants: genomic complexity and perspectives

“…Lastly, in Arabidopsis, AtTIP1;3 and AtTIP5;1 showed strong and limited expression in mature pollens and capacity to transport water and urea in a heterologous system (Soto et al, 2008). Each single mutation in these two genes generated a phenotype with a 30% reduction in pollen tube elongation and an 80% decrease in mitochondrial volume in pollen tubes when germinated in vitro in the absence of exogenous nitrogen sources.…”