Stalk cell polar ion transport provide for bladder‐based salinity tolerance in Chenopodium quinoa

Abstract

Chenopodium quinoa uses epidermal bladder cells (EBCs) to sequester excess salt. Each EBC complex consists of a leaf epidermal cell, a stalk cell, and the bladder.Under salt stress, sodium (Na + ), chloride (Cl À ), potassium (K + ) and various metabolites are shuttled from the leaf lamina to the bladders. Stalk cells operate as both a selectivity filter and a flux controller.In line with the nature of a transfer cell, advanced transmission electron tomography, electrophysiology, and fluorescent tracer flux studies revealed the stalk cell's polar organization and bladder-directed solute flow.RNA sequencing and cluster analysis revealed the gene expression profiles of the stalk cells. Among the stalk cell enriched genes, ion channels and carriers as well as sugar transporters were most pronounced. Based on their electrophysiological fingerprint and thermodynamic considerations, a model for stalk cell transcellular transport was derived.

Salt-tolerant alternative crops as sources of quality food to mitigate the negative impact of salinity on agricultural production

“…In quinoa plants, the specialized epidermal bladder cells (EBCs) that have a key role as salt sinks for external sequestration of Na + stand out (Böhm et al, 2018). But EBCs may be not only storage sites for excess of saline ions in leaf but also for the storage of water and different metabolites (Bazihizina et al, 2022). The leaf structure of amaranth is the typical Kranz anatomy of C4 plants, with the bundle sheath (BS) cells containing centripetally located chloroplasts and a layer of mesophyll cells surrounding these BS cells (Ueno, 2001).…”

The epidermal bladder cell‐free mutant of the salt‐tolerant quinoa challenges our understanding of halophyte crop salinity tolerance

“…Under salt stress, potassium (K + ), chloride (Cl À ), sodium (Na + ) to a minor degree, and various other metabolites are shuttled from the leaf lamina to the bladders. Via RNA sequencing and transport of the stalk cells Bazihizina et al (2022) recently showed that these transfer cells express genes encoding ion channels and carriers. In a working model, transcellular transport via HKT1, AKT1/HAK and an MFS mediates stalk cell K + , Cl À and Na + uptake from the epidermis and SOS1, SKOR1, and SLAH3 ion release towards the bladder.…”

Inhibition of SlSKOR by SlCIPK23‐SlCBL1/9 uncovers CIPK‐CBL‐target network rewiring in land plants

“…K + transport to the xylem is mediated by SKOR‐like voltage‐gated K + channels, HAK/KUP/KT transporters and NRT1.5‐like transporters (belonging to the NPF family; Gaymard et al ., 1998; Yang et al ., 2014; Han et al ., 2016; H. D. H. Li et al ., 2017). Besides root xylem K + load, voltage‐gated K + channels play crucial physiological roles in other plant cell types such as root cortex/epidermal cells, phloem cells, leaf epidermal cells (stalk, pavement, and guard cells), flesh berry cells, and pollen (Hirsch et al ., 1998; Deeken et al ., 2002; Mouline et al ., 2002; Hosy et al ., 2003; Lebaudy et al ., 2008; Cuéllar et al ., 2013; Bazihizina et al ., 2022; Nieves‐Cordones et al ., 2022). There is a large diversity of mechanisms that fine‐tune voltage‐gated K + channels activity and include cellular factors (membrane voltage, K + concentration, and pH) and interprotein interactions (heteromerization, clustering and interaction with SNARE, kinases and phosphatases; Lefoulon, 2021).…”