Root vacuolar Na<sup>+</sup> sequestration but not exclusion from uptake correlates with barley salt tolerance

Wu, Honghong; Shabala, Lana; Zhou, Meixue; Su, Nana; Wu, Qi; Ul-Haq, Tanveer; Jun, Zhu; Mancuso, Stefano; Azzarello, Elisa; Shabala, Sergey

doi:10.1111/tpj.14424

Cited by 81 publications

(57 citation statements)

References 84 publications

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“…3B and 4C). Lower shoot Na 1 concentration likely results from either the increase of root Na 1 exclusion or the decrease of root-to-shoot Na 1 transport (Wu et al, 2019;Huang et al, 2020). Interestingly, we confirmed that the lower shoot Na 1 concentration in RNAi lines is closely associated with a lower Na 1 transportation rate from roots to shoots ( Fig.…”

Section: Down-regulation Of Hvcam1 Enhances Salt Tolerance In Barleysupporting

confidence: 76%

Calmodulin HvCaM1 Negatively Regulates Salt Tolerance via Modulation of HvHKT1s and HvCAMTA4

Shen

et al. 2020

Plant Physiol.

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Calcium (Ca 21) signaling modulates sodium (Na 1) transport in plants; however, the role of the Ca 21 sensor calmodulin (CaM) in salt tolerance is elusive. We previously identified a salt-responsive calmodulin (HvCaM1) in a proteome study of barley (Hordeum vulgare) roots. Here, we employed bioinformatic, physiological, molecular, and biochemical approaches to determine the role of HvCaM1 in barley salt tolerance. CaM1s are highly conserved in green plants and probably originated from ancestors of green algae of the Chlamydomonadales order. HvCaM1 was mainly expressed in roots and was significantly up-regulated in response to long-term salt stress. Localization analyses revealed that HvCaM1 is an intracellular signaling protein that localizes to the root stele and vascular systems of barley. After treatment with 200 mM NaCl for 4 weeks, HvCaM1 knockdown (RNA interference) lines showed significantly larger biomass but lower Na 1 concentration, xylem Na 1 loading, and Na 1 transportation rates in shoots compared with overexpression lines and wild-type plants. Thus, we propose that HvCaM1 is involved in regulating Na 1 transport, probably via certain class I high-affinity potassium transporter (HvHKT1;5 and HvHKT1;1)-mediated Na 1 translocation in roots. Moreover, we demonstrated that HvCaM1 interacted with a CaM-binding transcription activator (HvCAMTA4), which may be a critical factor in the regulation of HKT1s in barley. We conclude that HvCaM1 negatively regulates salt tolerance, probably via interaction with HvCAMTA4 to modulate the downregulation of HvHKT1;5 and/or the up-regulation of HvHKT1;1 to reduce shoot Na 1 accumulation under salt stress in barley.

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Section: Down-regulation Of Hvcam1 Enhances Salt Tolerance In Barleysupporting

confidence: 76%

Calmodulin HvCaM1 Negatively Regulates Salt Tolerance via Modulation of HvHKT1s and HvCAMTA4

Shen

et al. 2020

Plant Physiol.

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“…The roots of TS‐21 and TS‐422 exhibited a lower Na + /K + ratio than TS‐577 and TS‐670 (Fig D), which is consistent with the results obtained from the population. Since decreased Na + /K + ratio is associated with increased salt tolerance (Munns & Tester, ), while vacuolar accumulation of Na + resulting in higher Na + /K + ratio has also been considered as a salt tolerance mechanism in plants (Wu et al , ), we thus evaluated the intracellular Na + accumulation at the elongation zone of roots of these four accessions. Our results showed that TS‐21 and TS‐422 plants accumulated less cytosolic Na + and were more resistant to high salinity than TS‐577 and TS‐670 plants (Fig E, Appendix Fig S1A).…”

Section: Resultsmentioning

confidence: 99%

“…Selective accumulation of Na + and K + in vegetative tissues at different developmental stages is essential for maintaining cellular ion homeostasis under high salinity (Hasegawa et al , ; Zhu, ). Therefore, understanding the molecular mechanisms and manipulation of Na + movement and distribution thus maintaining a low cytosolic Na + concentration is critical for improvement of plant salt tolerance (Wu et al , ). To our knowledge, this is the first report showing that a natural variation of a member of HAK/KUP/KT family clade IV significantly contributes to Na + homeostasis and salt tolerance in plants.…”

Section: Discussionmentioning

confidence: 99%

Loss of salt tolerance during tomato domestication conferred by variation in a Na ⁺ /K ⁺ transporter

et al. 2020

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Domestication has resulted in reduced salt tolerance in tomato. To identify the genetic components causing this deficiency, we performed a genome-wide association study (GWAS) for root Na + /K + ratio in a population consisting of 369 tomato accessions with large natural variations. The most significant variations associated with root Na + /K + ratio were identified within the gene SlHAK20 encoding a member of the clade IV HAK/KUP/KT transporters. We further found that SlHAK20 transports Na + and K + and regulates Na + and K + homeostasis under salt stress conditions. A variation in the coding sequence of SlHAK20 was found to be the causative variant associated with Na + /K + ratio and confer salt tolerance in tomato. Knockout mutations in tomato SlHAK20 and the rice homologous genes resulted in hypersensitivity to salt stress. Together, our study uncovered a previously unknown molecular mechanism of salt tolerance responsible for the deficiency in salt tolerance in cultivated tomato varieties. Our findings provide critical information for molecular breeding to improve salt tolerance in tomato and other crops.

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“…Other important Na + -selective transporter genes known as tonoplast-localized Na + /H + exchanger (NHX), are responsible for the sequestration of Na + into the vacuole, leading to the reduction of toxic Na + in the cytosol, in several plant species during salt stress [ 20 – 25 ]. Overexpression of AtNHX1 in Arabidopsis increases salt tolerance by compartmentalizing Na + into the vacuole in response to salt stress [ 20 , 21 ].…”

Section: Introductionmentioning

confidence: 99%

Tissue-specific expression analysis of Na+ and Cl− transporter genes associated with salt removal ability in rice leaf sheath

et al. 2020

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Background A significant mechanism of salt-tolerance in rice is the ability to remove Na+ and Cl− in the leaf sheath, which limits the entry of these toxic ions into the leaf blade. The leaf sheath removes Na+ mainly in the basal parts, and Cl− mainly in the apical parts. These ions are unloaded from the xylem vessels in the peripheral part and sequestered into the fundamental parenchyma cells at the central part of the leaf sheath. Results This study aimed to identify associated Na+ and Cl− transporter genes with this salt removal ability in the leaf sheath of rice variety FL 478. From 21 known candidate Na+ and Cl− transporter rice genes, we determined the salt responsiveness of the expression of these genes in the basal and apical parts, where Na+ or Cl− ions were highly accumulated under salinity. We also compared the expression levels of these transporter genes between the peripheral and central parts of leaf sheaths. The expression of 8 Na+ transporter genes and 3 Cl− transporter genes was up-regulated in the basal and apical parts of leaf sheaths under salinity. Within these genes, OsHKT1;5 and OsSLAH1 were expressed highly in the peripheral part, indicating the involvement of these genes in Na+ and Cl− unloading from xylem vessels. OsNHX2, OsNHX3, OsNPF2.4 were expressed highly in the central part, which suggests that these genes may function in sequestration of Na+ and Cl− in fundamental parenchyma cells in the central part of leaf sheaths under salinity. Furthermore, high expression levels of 4 candidate genes under salinity were associated with the genotypic variation of salt removal ability in the leaf sheath. Conclusions These results indicate that the salt removal ability in rice leaf sheath may be regulated by expressing various Na+ or Cl− transporter genes tissue-specifically in peripheral and central parts. Moreover, some genes were identified as candidates whose expression levels were associated with the genotypic variation of salt removal ability in the leaf sheath. These findings will enhance the understanding of the molecular mechanism of salt removal ability in rice leaf sheath, which is useful for breeding salt-tolerant rice varieties.

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Root vacuolar Na⁺ sequestration but not exclusion from uptake correlates with barley salt tolerance

Cited by 81 publications

References 84 publications

Calmodulin HvCaM1 Negatively Regulates Salt Tolerance via Modulation of HvHKT1s and HvCAMTA4

Calmodulin HvCaM1 Negatively Regulates Salt Tolerance via Modulation of HvHKT1s and HvCAMTA4

Loss of salt tolerance during tomato domestication conferred by variation in a Na ⁺ /K ⁺ transporter

Tissue-specific expression analysis of Na+ and Cl− transporter genes associated with salt removal ability in rice leaf sheath

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Root vacuolar Na+ sequestration but not exclusion from uptake correlates with barley salt tolerance

Cited by 81 publications

References 84 publications

Calmodulin HvCaM1 Negatively Regulates Salt Tolerance via Modulation of HvHKT1s and HvCAMTA4

Calmodulin HvCaM1 Negatively Regulates Salt Tolerance via Modulation of HvHKT1s and HvCAMTA4

Loss of salt tolerance during tomato domestication conferred by variation in a Na + /K + transporter

Tissue-specific expression analysis of Na+ and Cl− transporter genes associated with salt removal ability in rice leaf sheath

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Product

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Root vacuolar Na⁺ sequestration but not exclusion from uptake correlates with barley salt tolerance

Loss of salt tolerance during tomato domestication conferred by variation in a Na ⁺ /K ⁺ transporter