ER-localized auxin transporter PIN8 regulates auxin homeostasis and male gametophyte development in Arabidopsis

Abstract

Auxin is a key coordinative signal required for many aspects of plant development and its levels are controlled by auxin metabolism and intercellular auxin transport. Here we find that a member of PIn auxin transporter family, PIn8 is expressed in male gametophyte of Arabidopsis thaliana and has a crucial role in pollen development and functionality. Ectopic expression in sporophytic tissues establishes a role of PIn8 in regulating auxin homoeostasis and metabolism. PIn8 co-localizes with PIn5 to the endoplasmic reticulum (ER) where it acts as an auxin transporter. Genetic analyses reveal an antagonistic action of PIn5 and PIn8 in the regulation of intracellular auxin homoeostasis and gametophyte as well as sporophyte development. our results reveal a role of the auxin transport in male gametophyte development in which the distinct actions of ER-localized PIn transporters regulate cellular auxin homoeostasis and maintain the auxin levels optimal for pollen development and pollen tube growth.

Auxin transport and activity regulate stomatal patterning and development

“…The detailed information of above mutants can be found in Supplementary Tables 2 and 3. Expression patterns were analysed in young first leaves harbouring pPIN1: PIN1-GFP 37 , pPIN2:PIN2-GFP 37 , pPIN3:PIN3-GFP 17 , pPIN4:PIN4-GFP 24 , pPIN5:PIN5-GUS 38 , pPIN6:GUS 39 , pPIN7:PIN7-GFP 40 and pPIN8:PIN8-GFP 41 .…”

Master and servant: Regulation of auxin transporters by FKBPs and cyclophilins

“…Long PINs (PIN1-4,7) comprising a large cytoplasmic loop [5] are often polarly localized to a specific face of the plasma membrane in Arabidopsis root cells, in good correlation with the direction of the auxin flow [31]. By contrast, short PINs (PIN5, 6,8) are localized in the endomembrane system (most likely the endoplasmic reticulum (ER)) and appear to function in intracellular auxin transport and homeostasis [32,33]. Recently, a second family of ER-localized auxin transporters, called PILS (for PIN-LIKES), was also shown to regulate auxin homeostasis [34], although their role in auxin transport is less clear.…”

Adaptor Protein Complex 2–Mediated Endocytosis Is Crucial for Male Reproductive Organ Development in Arabidopsis

“…According to publicly available microarray data, PIN8 showed the highest expression in pollen and filaments, whereas the expression levels of PIN2 and PIN1 are moderate or barely detectable, respectively. However, PIN8 is reported to localize to the endoplasmic reticulum (Ding et al, 2012). Accordingly, to reveal a possible relationship to AP2M function in filament growth, we initially examined localization of GFP-tagged PIN2 in the filaments.…”