Regulation of asymmetric polar auxin transport by PsPIN1 in endodermal tissues of etiolated Pisum sativum epicotyls: focus on immunohistochemical analyses

Abstract

This manuscript reports the production of specific polyclonal antibodies for PsPIN1, a putative auxin efflux carrier in Alaska pea (Pisum sativum L.) plants, and the cellular immunolocalization of PsPIN1. When pea seeds were set with the seed axis horizontal to the upper surface of a rockwool block, and allowed to germinate and grow for 3 days in the dark, the epicotyl grew upward. On the other hand, the application of 2,3,5-triiodobenzoic acid (TIBA) inhibited graviresponse. In the subapical epicotyl regions, PsPIN1 has been found to localize in the basal side of the plasma membrane of cells in endodermal tissues. Asymmetric PsPIN1 localization between the proximal and distal sides of the epicotyl was observed, the total amounts of PsPIN1 being more abundant in the proximal side. The asymmetric PsPIN1 distribution between the proximal and distal sides of the epicotyl was well correlated with unequal polar auxin transport as well as asymmetric accumulation of mRNA of PsPIN1 (Ueda et al. in Biol Sci Space 26:32-41, 2012; Ueda et al. in Plant Biol 16(suppl 1):43-49, 2014). In the proximal side of an apical hook, PsPIN1 localized in the basal side of the plasma membrane of cells in endodermal tissues, whereas in the distal side, the abundant distribution of PsPIN1 localized in the basal-lower (endodermal) side of the basal plasma membrane, suggesting possible lateral auxin movement from the distal side to the proximal side in this region. The application of TIBA significantly reduced the amount of PsPIN1 in the proximal side of epicotyls, but little in the distal side. These results suggest that unequal auxin transport in epicotyls during the early growth stage of etiolated pea seedlings is derived from asymmetric PsPIN1 localization in the apical hook and subapical region of epicotyls, and that asymmetric transport between the proximal and distal sides of epicotyls is required for the graviresponse of epicotyls.

Mitogen-Activated Protein Kinase Cascades in Plant Hormone Signaling

“…The phytohormone auxin, indole 3-acetic acid (IAA), plays a crucial role in plant growth and development, including embryogenesis ( Friml et al, 2003 ; Blilou et al, 2005 ; Morris et al, 2005 ; Leyser, 2017 ), organogenesis ( Benkova et al, 2003 ; Reinhardt et al, 2003 ; Heisler et al, 2005 ; Smekalova et al, 2014 ; Contreras-Cornejo et al, 2015 ; Enders et al, 2017 ; Wójcikowska and Gaj, 2017 ; Corredoira et al, 2017 ; Zhao, 2018 ), tissue patterning, tropism and growth responses to environmental stimuli ( Benkova et al, 2003 ; Leyser, 2003 ; Reinhardt et al, 2003 ; Morris et al, 2004 ; Simonini et al, 2016 ; Liu et al, 2017 ; Kamada et al, 2018 ). The involvement of auxin in this multiplicity of biological processes results from its regulation of cell division, expansion and differentiation ( Chen and Baluska, 2013 ).…”

Dehydrocostus lactone, a naturally occurring polar auxin transport inhibitor, inhibits epicotyl growth by interacting with auxin in etiolated Pisum sativum seedlings

“…Phylogenetic relationships revealed that PsPIN1 belongs to the same clade as AtPIN1, and PsPIN2 and PsPIN3 belong to the same subclade including AtPIN3, AtPIN4, and AtPIN7 [39]. Immuno-histochemical analysis using specific polyclonal antibodies for PsPIN1 demonstrated the localization of PsPIN1 in the basal side of the plasma membrane of cells in endodermal tissues in etiolated pea seedlings [48], suggesting that PsPIN1 plays a fundamentally important role in directional transport of auxin as does AtPIN1. These results suggest a possible involvement of reduced levels of PsAUX1 and PsPIN1 carrier proteins in auxin influx and efflux, respectively, via a reduction of expression of both PsAUX1 and PsPIN1 mRNA, in the reduction of polar auxin transport by DHCL in etiolated pea epicotyls.…”

“…Thus, polar auxin transport regulated by PsAUX1 and PsPIN1 carrier proteins of auxin might be highly regulated by the level of mRNA accumulation affected by endogenous IAA. NPA inhibits IAA transport by specific binding to a so-called NPA receptor, thereby blocking the carrier-mediated efflux of IAA [48], whereas IAA does not compete with NPA for the binding site [9]. Morphactin has been shown to bind to the NPA receptor, suggesting that it acts by the same mechanism as NPA [50].…”

Stepwise signal transduction cascades under salt stress in leaves of wild barley (Hordeum spontaneum)

“…Hormones, like auxin, abscisic acid (ABA), jasmonic acid (JA), salicylic acid (SA), ethylene (ET), brassinosteroids (BR) and gibberellins (GA), can differentially select distinct MAPK module structures (or cascade) that subsequently trigger a required biological process [20,21,24,42,43,[45][46][47][48][49][50][51]. MAPK normally exchanges signalling with auxin.…”