A Single Amino-Acid Substitution in the Sodium Transporter HKT1 Associated with Plant Salt Tolerance

Ali, Akhtar; Raddatz, Natalia; Aman, Rashid; Kim, Songmi; Park, Hyeong Cheol; Jan, Masood; Baek, Dongwon; Khan, Irfan Ullah; Oh, Dong-Ha; Lee, Sang Yeol; Bressan, Ray A.; Lee, Keun Woo; Maggio, Aurelio; Pardo, José M.; Bohnert, Hans J.; Yun, Dae‐Jin

doi:10.1104/pp.16.00569

Cited by 90 publications

(99 citation statements)

References 65 publications

(109 reference statements)

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“…Qualitative differences clearly appear between the 3 MtHKT curves. In the case of MtHKT1;5, the I-V curve is quasi linear in the whole range of recorded currents, inward or outward, as reported for the Arabidopsis AtHKT1 (Xue et al, 2011; Ali et al, 2016) and most other HKT subfamily 1 transporters characterized from dicots (Fairbairn et al, 2000; Almeida et al, 2014a) as well as from monocots (Suzuki et al, 2016). In contrast, in the case of MtHKT1;4, the shape of the I-V curve clearly shows that the ability of this transporter to mediate inward currents is stronger than its ability to mediate outward currents.…”

Section: Resultssupporting

confidence: 65%

TheMedicago truncatulaHKT family: Ion transport properties and regulation of expression upon abiotic stresses and symbiosis

Thouin

Guo

Zribi

et al. 2019

Preprint

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Soil salinity is one of the most important abiotic stresses affecting plant growth. In legumes, symbiotic nitrogen fixation in nodules is affected by salt stress, and salinity tolerance is variable among species. Genes from the High affinity K + Transporter (HKT) family are known to play crucial roles in salt stress tolerance in different plant species. In legumes these transporters are still very poorly characterized. . Here we study the HKT transporter family from the model legume Medicago trunacatula, which is moderately tolerant to salinity. The genome of this species comprises five HKT genes, hereafter named MtHKT1;1 to MtHKT1;5. Phylogenetic analysis indicated that the MtHKT polypeptides belong to HKT subfamily 1. Three members (MtHKT1;2, MtHKT1;4 and MtHKT1;5) of the Medicago truncatula family were cloned and expressed in Xenopus oocytes. Their electrophysiological properties revealed a permeability 10 times higher for Na + than for K + and varying rectification properties. Expression analyses of the three MtHKT genes under different biotic and abiotic conditions suggested that MtHKT1;5 is the main transporter from this family in the root, the three genes sharing a decrease of expression in drought and salt stress conditions in non inoculated plants as well as plants inoculated with rhizobia. In the shoot, the three MtHKT would be present at similar levels independently on the applied stresses. Based on biomass and ion content analysis, the nodule appeared as the most sensitive organ to the applied salt and drought stresses. The level of expression of the three MtHKT genes was strongly decreased by both stresses in the nodule.Soil salinity is one of the most important abiotic stresses affecting plant growth (Munns et Gilliham, 2015). Most crop species are poorly tolerant to salt stress and displays reduced yields when the electrical conductivity of the soil solution (at saturation) becomes higher than ca. 4 dS/m (USDA-ARS, 2008), i.e. higher than that of a solution containing ca. 40 mM NaCl and, which generates an osmotic pressure of approximately 0.2 MPa (Munns et Tester, 2008; Marschner, 2012). Such soils are then classified as saline. Natural salinity and salinization due to irrigation with poor quality water challenge agriculture in 6 % to 10 % of the earth's land area (Eynard et al., 2005; Munns et Tester, 2008). Enhanced demand for irrigation due to both population increase and climate change, are predicted to dramatically speed up loss of arable land (Eckholm, 1975; Shabala et al., 2014).Soil salinity results in both an osmotic and an ionic stress for most plants. Osmotic stress results from the fact that high external salt concentrations reduce soil water availability due to the decrease in water potential, and thus make it harder for roots to extract water, which is a situation resembling drought. The so-called ionic stress corresponds to the fact that high salt concentrations within the plant tissues have deleterious effects on plant metabolism and physiology. Molecular, genetic and physiolog...

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Section: Resultssupporting

confidence: 65%

TheMedicago truncatulaHKT family: Ion transport properties and regulation of expression upon abiotic stresses and symbiosis

Thouin

Guo

Zribi

et al. 2019

Preprint

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“…Both rice OsHKT1;1 and 1;3 appear to rectify more strongly than VisHKT1;1‐e and wheat TaHKT1.5‐D S506R , and neither contain a residue equivalent to Arg‐534. TsHKT1;2 and AtHKT1 N211D showed inward rectification of Na + transport, but the reverse D207N mutation in TsHKT1;2 did not abrogate this (Ali et al ., ). These findings indicate that additional residues influence rectification in HKT proteins.…”

Section: Discussionmentioning

confidence: 97%

“…These findings indicate that additional residues influence rectification in HKT proteins. Ali et al (2016) suggested that inward rectification of AtHKT1;1 N211D would impose a greater Na + retention in root cells, preventing Na + efflux to the xylem apoplast. However, they found no difference in shoot Na + accumulation between Arabidopsis plants expressing either the rectifying or nonrectifying AtHKT1 variants.…”

Section: Researchmentioning

confidence: 99%

“…Proteins from the HKT1 subgroup selectively transport Na + over other cations (M€ aser et al, 2002;Horie et al, 2009;Waters et al, 2013), and confer Na + exclusion from shoots through retrieval of Na + from root xylem vessels into surrounding xylem parenchyma cells (Sunarpi et al, 2005;Davenport et al, 2007;Møller et al, 2009;Byrt et al, 2014). Emerging evidence indicates that molecular mechanisms of HKT1-mediated salinity tolerance between plants may depend upon not only expression differences, but also, in some cases, subtle differences in functional properties that may be attributed to single amino acid substitutions and possible allelic variations (Ren et al, 2005;Rus et al, 2006;Baxter et al, 2010;Cotsaftis et al, 2012;Ali et al, 2016;Tounsi et al, 2016). The benefits of identifying natural variants of HKT has been demonstrated with HKT1.5 from salt-tolerant wheat Triticum monococcum which, when introgressed into salt-sensitive T. durum, increased grain yield on saline soil by 25% in the field (Munns et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

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Functional differences in transport properties of natural HKT1;1 variants influence shoot Na⁺ exclusion in grapevine rootstocks

Henderson

Dunlevy

et al. 2017

New Phytologist

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Under salinity, Vitis spp. rootstocks can mediate salt (NaCl) exclusion from grafted V. vinifera scions enabling higher grapevine yields and production of superior wines with lower salt content. Until now, the genetic and mechanistic elements controlling sodium (Na ) exclusion in grapevine were unknown. Using a cross between two Vitis interspecific hybrid rootstocks, we mapped a dominant quantitative trait locus (QTL) associated with leaf Na exclusion (NaE) under salinity stress. The NaE locus encodes six high-affinity potassium transporters (HKT). Transcript profiling and functional characterization in heterologous systems identified VisHKT1;1 as the best candidate gene for controlling leaf Na exclusion. We characterized four proteins encoded by unique VisHKT1;1 alleles from the parents, and revealed that the dominant HKT variants exhibit greater Na conductance with less rectification than the recessive variants. Mutagenesis of VisHKT1;1 and TaHKT1.5-D from bread wheat, demonstrated that charged amino acid residues in the eighth predicted transmembrane domain of HKT proteins reduces inward Na conductance, and causes inward rectification of Na transport. The origin of the recessive VisHKT1;1 alleles was traced to V. champinii and V. rupestris. We propose that the genetic and functional data presented here will assist with breeding Na -tolerant grapevine rootstocks.

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“…Induction of HKT1:1 expression upon initial imposition of salt stress in both leaves and roots may promote Na + exclusion tolimit Na + toxcity in the respective tissues(Zhang et al, 2018). However, with increasing salt stress treatment time, the marginal expression of HKT1:1genemay regulate the retrevial of Na + from the xylem (Davenport et al, 2007; Ali et al, 2016). The expression levels of CLC1 indicates that CLC1 may not be involved in the Cl - vacuolar sequestation (Wei et al, 2016).…”

Section: Discussionmentioning

confidence: 99%

Systematic hormone-metabolite network provides insights of high salinity tolerance inPongamia pinnata(L.) pierre

Marriboina

Sharma

Sengupta

et al. 2020

Preprint

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Salinity stress results significant losses in plant productivity, and loss of cultivable lands. Although Pongamia pinnata is reported to be a salt tolerant semiarid tree crop, the adaptive mechanisms to saline environment are elusive. The present investigation describes alterations in hormonal and metabolic responses in correlation with physiological and molecular variations in leaves and roots of Pongamia at sea salinity level (3% NaCl) for 8 days. At physiological level, salinity induced adjustments in plant morphology, leaf gas exchange and ion accumulation patterns were observed. Our study also revealed that phytohormones including JAs and ABA play crucial role in promoting the salt adaptive strategies such as apoplasmic Na+ sequestration and cell wall lignification in leaves and roots of Pongamia. Correlation studies demonstrated that hormones including ABA, JAs and SA showed a positive interaction with selective compatible metabolites (sugars, polyols and organic acids) to aid in maintaining osmotic balance and conferring salt tolerance to Pongamia. At the molecular level, our data showed that differential expression of transporter genes as well as antioxidant genes regulate the ionic and ROS homeostasis in Pongamia. Collectively, these results shed new insights on an integrated physiological, structural, molecular and metabolic adaptations conferring salinity tolerance to Pongamia.High lightOur data, for the first time, provide new insights for an integrated molecular and metabolic adaptation conferring salinity tolerance in Pongamia. The present investigation describes alterations in hormonal and metabolic responses in correlation with physiological and molecular variations in Pongamia at sea salinity level (3% NaCl) for 8 days.

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A Single Amino-Acid Substitution in the Sodium Transporter HKT1 Associated with Plant Salt Tolerance

Cited by 90 publications

References 65 publications

TheMedicago truncatulaHKT family: Ion transport properties and regulation of expression upon abiotic stresses and symbiosis

TheMedicago truncatulaHKT family: Ion transport properties and regulation of expression upon abiotic stresses and symbiosis

Functional differences in transport properties of natural HKT1;1 variants influence shoot Na⁺ exclusion in grapevine rootstocks

Systematic hormone-metabolite network provides insights of high salinity tolerance inPongamia pinnata(L.) pierre

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A Single Amino-Acid Substitution in the Sodium Transporter HKT1 Associated with Plant Salt Tolerance

Cited by 90 publications

References 65 publications

TheMedicago truncatulaHKT family: Ion transport properties and regulation of expression upon abiotic stresses and symbiosis

TheMedicago truncatulaHKT family: Ion transport properties and regulation of expression upon abiotic stresses and symbiosis

Functional differences in transport properties of natural HKT1;1 variants influence shoot Na+ exclusion in grapevine rootstocks

Systematic hormone-metabolite network provides insights of high salinity tolerance inPongamia pinnata(L.) pierre

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Functional differences in transport properties of natural HKT1;1 variants influence shoot Na⁺ exclusion in grapevine rootstocks