Epidermal bladder cells confer salinity stress tolerance in the halophyte quinoa and Atriplex species

Abstract

Epidermal bladder cells (EBCs) have been postulated to assist halophytes in coping with saline environments. However, little direct supporting evidence is available. Here, Chenopodium quinoa plants were grown under saline conditions for 5 weeks. One day prior to salinity treatment, EBCs from all leaves and petioles were gently removed by using a soft cosmetic brush and physiological, ionic and metabolic changes in brushed and non-brushed leaves were compared. Gentle removal of EBC neither initiated wound metabolism nor affected the physiology and biochemistry of control-grown plants but did have a pronounced effect on salt-grown plants, resulting in a salt-sensitive phenotype. Of 91 detected metabolites, more than half were significantly affected by salinity. Removal of EBC dramatically modified these metabolic changes, with the biggest differences reported for gamma-aminobutyric acid (GABA), proline, sucrose and inositol, affecting ion transport across cellular membranes (as shown in electrophysiological experiments). This work provides the first direct evidence for a role of EBC in salt tolerance in halophytes and attributes this to (1) a key role of EBC as a salt dump for external sequestration of sodium; (2) improved K retention in leaf mesophyll and (3) EBC as a storage space for several metabolites known to modulate plant ionic relations.

iTRAQ-Based Quantitative Proteomic Analysis of Heat Stress-Induced Mechanisms in Pepper Seedlings

“…This nding indicated that the activity of TCA cycle was more signi cantly decreased in HT compared with HS. It has been reported that the reduced consumption of organic acids caused by the decreased activity of TCA cycle may contribute to the synthesis of compounds to cope with stressful condition [35,36]. Therefore, reducing the activity of TCA cycle in HT might be conducive to the synthesis of osmosis substances to cope with heat stress.…”

Analysis of Stress Resistance Using Next Generation Techniques

“…This method is applied in several approaches, e.g., to identify differentially expressed genes (DEGs) between different conditions, tissues or ecotypes. Several studies on salt tolerance and its sequestration in EBCs were performed [28,33,34]. In combination with the quinoa reference genome, Zou and colleagues analyzed the transcriptome of EBCs and leaves under salt-treated and non-treated conditions.…”

“…As a next experimental step, quinoas EBCs were mechanically removed prior to the salt treatment resulting in the loss of plant's salt tolerance. This procedure dramatically altered the metabolite composition demonstrating that EBCs also serve as metabolite storage [33].…”

Revealing mechanisms of salinity tissue tolerance in succulent halophytes: A case study for Carpobrotus rossi

“…All authors are at consensus that the key trait that differentiates halophytes from glycophytes is the ability of the former for an efficient sequestration of the load away from the metabolically active tissues. This is achieved by either a regular secreting the excessive amounts of salt via specialized salt glands (Dassanayake & Larkin, ; Yuan, Leng, & Wang, ) or by depositing it into external (epidermal bladder cells, EBC; Kiani‐Pouya et al, ) or internal (storage vacuoles) structures (Bonales‐Alatorre et al, ; Shabala et al, ). Amongst these mechanisms, salt sequestration in EBC is the most studied, both at physiological and molecular levels (Agarie et al, ; Barkla, Veraestrella, & Raymond, ; Hariadi, Marandon, Tian, Jacobsen, & Shabala, ; Oh et al, ; Shabala et al, ; Zou et al, ).…”

“…secreting the excessive amounts of salt via specialized salt glands (Dassanayake & Larkin, 2017;Yuan, Leng, & Wang, 2016) or by depositing it into external (epidermal bladder cells, EBC; Kiani-Pouya et al, 2017) or internal (storage vacuoles) structures Shabala et al, 2014). Amongst these mechanisms, salt sequestration in EBC is the most studied, both at physiological and molecular levels (Agarie et al, 2007;Barkla, Veraestrella, & Raymond, 2016;Hariadi, Marandon, Tian, Jacobsen, & Shabala, 2011;Oh et al, 2015;Shabala et al, 2012;Zou et al, 2017).…”