Nomenclature for HKT transporters, key determinants of plant salinity tolerance

Platten, John Damien; Cotsaftis, Olivier; Berthomieu, Pierre; Bohnert, Hans J.; Davenport, Romola; Fairbairn, David J.; Horie, Tomoaki; Leigh, R. A.; Lin, Hong; Luan, Sheng; Mäser, Pascal; Pantoja, Omar; Rodríguez‐Navarro, Alonso; Schachtman, Daniel P.; Schroeder, Julian I.; Sentenac, Hervé; Uozumi, Nobuyuki; Véry, Anne Aliénor; Zhu, Jieping; Dennis, Elizabeth S.; Tester, Mark

doi:10.1016/j.tplants.2006.06.001

Cited by 320 publications

(295 citation statements)

References 15 publications

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“…The data from the current study confirmed that Saltol contributes to Na + /K + homeostasis with an LOD of 7.6 and R 2 of 27% across the 140 RILs and a 30% decrease in the shoot Na-K ratio, from 1.7 to 1.2 in the IR29/Pokkali backcross lines, while the Saltol effect on SES scores in the QTL population and backcross lines was much smaller. The fact that Saltol affected the Na-K ratio more than other traits supports the possibility that the sodium transporter SKC1 (OsHKT1;5 as in Platten et al 2006) may be the causal gene underlying the Saltol QTL. SKC1 was found to encode a sodium transporter that helps control Na + /K + homeostasis through unloading of Na + from the xylem (Ren et al 2005), which has been suggested to function primarily in roots to reduce the amount of Na + ions that are transported to the leaves (Hauser and Horie 2010).…”

Section: Discussionmentioning

confidence: 83%

Characterizing the Saltol Quantitative Trait Locus for Salinity Tolerance in Rice

Thomson

Ocampo

Egdane

et al. 2010

Rice

439

370

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This study characterized Pokkali-derived quantitative trait loci (QTLs) for seedling stage salinity tolerance in preparation for use in marker-assisted breeding. An analysis of 100 SSR markers on 140 IR29/Pokkali recombinant inbred lines (RILs) confirmed the location of the Saltol QTL on chromosome 1 and identified additional QTLs associated with tolerance. Analysis of a series of backcross lines and near-isogenic lines (NILs) developed to better characterize the effect of the Saltol locus revealed that Saltol mainly acted to control shoot Na + /K + homeostasis. Multiple QTLs were required to acquire a high level of tolerance. Unexpectedly, multiple Pokkali alleles at Saltol were detected within the RIL population and between backcross lines, and representative lines were compared with seven Pokkali accessions to better characterize this allelic variation. Thus, while the Saltol locus presents a complex scenario, it provides an opportunity for markerassisted backcrossing to improve salt tolerance of popular varieties followed by targeting multiple loci through QTL pyramiding for areas with higher salt stress.

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Section: Discussionmentioning

confidence: 83%

Characterizing the Saltol Quantitative Trait Locus for Salinity Tolerance in Rice

Thomson

Ocampo

Egdane

et al. 2010

Rice

439

370

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“…The Trk/HKT transporters are important for cellular K ϩ acquisition in microorganisms, since trk null mutant yeast or bacteria exhibit growth phenotypes on media containing low K ϩ concentrations (20,46). The roles of the Trk/HKT transporters in plants are more diverse, including Na ϩ distribution (10,33,47), osmoregulation (32), and salt tolerance (39). So far, no HKT/Trk transporter has been described from the metazoa or protista.…”

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confidence: 99%

A Trk/HKT-Type K ⁺ Transporter from Trypanosoma brucei

et al. 2010

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The molecular mechanisms of K ؉ homeostasis are only poorly understood for protozoan parasites. Trypanosoma brucei subsp. parasites, the causative agents of human sleeping sickness and nagana, are strictly extracellular and need to actively concentrate K ؉ from their hosts' body fluids. The T. brucei genome contains two putative K ؉ channel genes, yet the trypanosomes are insensitive to K ؉ antagonists and K ؉ channelblocking agents, and they do not spontaneously depolarize in response to high extracellular K ؉ concentrations. However, the trypanosomes are extremely sensitive to K ؉ ionophores such as valinomycin. Surprisingly, T. brucei possesses a member of the Trk/HKT superfamily of monovalent cation permeases which so far had only been known from bacteria, archaea, fungi, and plants. The protein was named TbHKT1 and functions as a Na ؉ -independent K ؉ transporter when expressed in Escherichia coli, Saccharomyces cerevisiae, or Xenopus laevis oocytes. In trypanosomes, TbHKT1 is expressed in both the mammalian bloodstream stage and the Tsetse fly midgut stage; however, RNA interference (RNAi)-mediated silencing of TbHKT1 expression did not produce a growth phenotype in either stage. The presence of HKT genes in trypanosomatids adds a further piece to the enigmatic phylogeny of the Trk/HKT superfamily of K ؉ transporters. Parsimonial analysis suggests that the transporters were present in the first eukaryotes but subsequently lost in several of the major eukaryotic lineages, in at least four independent events.

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“…Biochemical and genetic analyses have demonstrated that OsSOS1 is a functional homolog of SOS1. Plasma membrane preparations from yeast expressing OsSOS1 show [99,131,137]. SKC1 is preferentially expressed in parenchyma cells surrounding xylem vessels and up-regulated by salinity in roots.…”

Section: Sodium Transportersmentioning

confidence: 99%

Toward Understanding Molecular Mechanisms of Abiotic Stress Responses in Rice

Gao

Chao

Lin

2008

Rice

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Plants have evolved delicate mechanisms to cope with environmental stress. Following exposure to environmental stimuli, extracellular signals are perceived and transmitted through signal transduction cascades. Upon receipt and transmission of the signals, a number of stressrelated genes are induced, leading to stress adaptation in plant cells. Rice, which is a critical food grain for a large portion of the world's population, is frequently impacted by several abiotic stressors, the most important of which are drought, salinity, and cold. Exposure to environmental conditions outside of acceptable tolerance ranges can negatively affect rice growth and production. In this paper, a review of rice responses to abiotic stress is presented, with particular attention to the genes and pathways related to environmental stress tolerance. It is apparent that, while progress has been made in identifying genes involved in stress adaptation, many questions remain. Understanding the mechanisms of stress response in rice is important for all research designed to develop new rice varieties with improved tolerance.Keywords Abiotic stress . Rice . Signal perception and transduction . Transcription factor . Stress tolerance Plant growth and productivity can be adversely affected by abiotic stress. Plants are exposed to any number of potentially adverse environmental conditions such as water deficit, high salinity, extreme temperature, and submergence. In response, plants have evolved delicate mechanisms, from the molecular to the physiological level, to adapt to stressful environments.Rice is the staple food for more than half of the world's population. Evolved in a semi-aquatic, low-radiation habitat, rice exhibits distinct tolerance and susceptibilities to abiotic stresses among domesticated cereal crops [92]. Rice thrives in waterlogged soil and can tolerate submergence at levels that would kill other crops, and is moderately tolerant of salinity and soil acidity but is highly sensitive to drought and cold [92]. Cultivated over a broad region between 45°north and south latitudes, rice plants are faced with low temperature in temperate regions, submergence in tropical regions, water deficit in humid tropics, and other stressors [109].Arabidopsis is a good model in plant molecular biology and genetics research, and the majority of studies examining the impacts of abiotic stress have employed this plant [37,85,165,183,193]. The signaling pathways and regulatory network in Arabidopsis have been well characterized and well reviewed. Although progresses were also made on rice, reviews were less focused on this most important crop because of little functional genes characterized. Recent years, multiple genes contributing to abiotic stress responses in rice were identified by using genetics, reverse genetics, and molecular biology method. Here, we Rice

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Nomenclature for HKT transporters, key determinants of plant salinity tolerance

Cited by 320 publications

References 15 publications

Characterizing the Saltol Quantitative Trait Locus for Salinity Tolerance in Rice

Characterizing the Saltol Quantitative Trait Locus for Salinity Tolerance in Rice

A Trk/HKT-Type K ⁺ Transporter from Trypanosoma brucei

Toward Understanding Molecular Mechanisms of Abiotic Stress Responses in Rice

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Nomenclature for HKT transporters, key determinants of plant salinity tolerance

Cited by 320 publications

References 15 publications

Characterizing the Saltol Quantitative Trait Locus for Salinity Tolerance in Rice

Characterizing the Saltol Quantitative Trait Locus for Salinity Tolerance in Rice

A Trk/HKT-Type K + Transporter from Trypanosoma brucei

Toward Understanding Molecular Mechanisms of Abiotic Stress Responses in Rice

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A Trk/HKT-Type K ⁺ Transporter from Trypanosoma brucei