Inventory and Functional Characterization of the HAK Potassium Transporters of Rice

Bañuelos, María Antonia; Garciadeblás, Blanca; Cubero, Beatriz; Rodríguez‐Navarro, Alonso

doi:10.1104/pp.007781

Cited by 290 publications

(297 citation statements)

References 51 publications

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“…However, rice gene families are in general similar in size to those in Arabidopsis, such as the various kinase families shown in Figure 1 and other gene families, such as HAK potassium transporters (Banuelos et al, 2002), LRR extensins (Baumberger et al, 2003), P-type ATPases (Baxter et al, 2003), Dof transcription factors (Lijavetzky et al, 2003), and ATP binding cassette transporters (Jasinski et al, 2003). Therefore, the RLK/Pelle family may represent one of the gene families differentially expanded in rice.…”

Section: History Of the Rlk/pelle Family Expansion In Land Plantsmentioning

confidence: 99%

Comparative Analysis of the Receptor-Like Kinase Family in Arabidopsis and Rice[W]

et al. 2004

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Receptor-like kinases (RLKs) belong to the large RLK/Pelle gene family, and it is known that the Arabidopsis thaliana genome contains >600 such members, which play important roles in plant growth, development, and defense responses. Surprisingly, we found that rice (Oryza sativa) has nearly twice as many RLK/Pelle members as Arabidopsis does, and it is not simply a consequence of a larger predicted gene number in rice. From the inferred phylogeny of all Arabidopsis and rice RLK/Pelle members, we estimated that the common ancestor of Arabidopsis and rice had >440 RLK/Pelles and that largescale expansions of certain RLK/Pelle members and fusions of novel domains have occurred in both the Arabidopsis and rice lineages since their divergence. In addition, the extracellular domains have higher nonsynonymous substitution rates than the intracellular domains, consistent with the role of extracellular domains in sensing diverse signals. The lineagespecific expansions in Arabidopsis can be attributed to both tandem and large-scale duplications, whereas tandem duplication seems to be the major mechanism for recent expansions in rice. Interestingly, although the RLKs that are involved in development seem to have rarely been duplicated after the Arabidopsis-rice split, those that are involved in defense/disease resistance apparently have undergone many duplication events. These findings led us to hypothesize that most of the recent expansions of the RLK/Pelle family have involved defense/resistance-related genes.

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Section: History Of the Rlk/pelle Family Expansion In Land Plantsmentioning

confidence: 99%

Comparative Analysis of the Receptor-Like Kinase Family in Arabidopsis and Rice[W]

et al. 2004

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“…Other such possible routes include nonselective cation channels (NSCCs), such as the cyclic nucleotide gated (CNGC) and/or glutamate receptor (GLR) channels (Lemtiri-Chlieh and Berkowitz 2004;Meyerhoff et al 2005;Wolf et al 2005;Zhao et al 2011; see also Véry et al 1998;Tyerman and Skerrett 1999). It is also possible that members of the KUP/HAK/KT family, generally attributed to primary K + uptake in roots (Gierth and Mäser 2007), might contribute, as these have been shown to be capable of mediating low-affinity Na + fluxes in roots under special circumstances (Santa-María et al 1997;Takahashi et al 2007; see also Mäser et al 2002), and are also expressed in shoots (Kim et al 1998;Rubio et al 2000;Bañuelos et al 2002;Su et al 2002). However, a specific demonstration in guard cell opening and closing has not been made in any study of which we are aware.…”

Section: Sodium As a Nutrientmentioning

confidence: 99%

Sodium as nutrient and toxicant

et al. 2013

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Background Sodium (Na + ) is one of the most intensely researched ions in plant biology and has attained a reputation for its toxic qualities. Following the principle of Theophrastus Bombastus von Hohenheim (Paracelsus), Na + is, however, beneficial to many species at lower levels of supply, and in some, such as certain C4 species, indeed essential. Scope Here, we review the ion's divergent roles as a nutrient and toxicant, focusing on growth responses, membrane transport, stomatal function, and paradigms of ion accumulation and sequestration. We examine connections between the nutritional and toxic roles throughout, and place special emphasis on the relationship of Na + to plant potassium (K + ) relations and homeostasis. Conclusions Our review investigates intriguing connections and disconnections between Na + nutrition and toxicity, and concludes that several leading paradigms in the field, such as on the roles of Na + influx and tissue accumulation or the cytosolic K + /Na + ratio in the development of toxicity, are currently insufficiently substantiated and require a new, critical approach.

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“…The absence of evidence that subfamily 2 HKT transporters contribute to K + fluxes in planta, while these systems are clearly permeable to K + , highly expressed in plant cells, and functional in the cell membrane (as shown by their strong contribution to Na + transport) might be due to redundancy in K + transport systems from different families. For instance, in root periphery tissues, when plants are grown in classical environmental conditions and/or when experiments are performed in classical bath solutions, K + transport activity of HKT transporters might be masked by that of K + channels from the Shaker family (Sentenac et al, 1992;Hirsch et al, 1998;Santa-María et al, 2000;Pilot et al, 2003;Véry and Sentenac, 2003) and/or H + -K + symporters from the KUP/HAK family (Santa-María et al, 2000;Bañ uelos et al, 2002;Gierth and Mäser, 2007). The question of the existence of Na + -K + symport activity in plants, owing to its importance, clearly deserves to be readdressed.…”

Section: Expression Patterns and Roles In The Plantmentioning

confidence: 99%

Diversity in Expression Patterns and Functional Properties in the Rice HKT Transporter Family

et al. 2009

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Plant growth under low K + availability or salt stress requires tight control of K + and Na + uptake, long-distance transport, and accumulation. The family of membrane transporters named HKT (for High-Affinity K + Transporters), permeable either to K + and Na + or to Na + only, is thought to play major roles in these functions. Whereas Arabidopsis (Arabidopsis thaliana) possesses a single HKT transporter, involved in Na + transport in vascular tissues, a larger number of HKT transporters are present in rice (Oryza sativa) as well as in other monocots. Here, we report on the expression patterns and functional properties of three rice HKT transporters, OsHKT1;1, OsHKT1;3, and OsHKT2;1. In situ hybridization experiments revealed overlapping but distinctive and complex expression patterns, wider than expected for such a transporter type, including vascular tissues and root periphery but also new locations, such as osmocontractile leaf bulliform cells (involved in leaf folding). Functional analyses in Xenopus laevis oocytes revealed striking diversity. OsHKT1;1 and OsHKT1;3, shown to be permeable to Na + only, are strongly different in terms of affinity for this cation and direction of transport (inward only or reversible). OsHKT2;1 displays diverse permeation modes, Na + -K + symport, Na + uniport, or inhibited states, depending on external Na + and K + concentrations within the physiological concentration range. The whole set of data indicates that HKT transporters fulfill distinctive roles at the whole plant level in rice, each system playing diverse roles in different cell types. Such a large diversity within the HKT transporter family might be central to the regulation of K + and Na + accumulation in monocots.Although it is not clear what levels of Na + are toxic in the plant cell cytosol and actually unacceptable in vivo, the hypothesis that this cation must be excluded from the cytoplasm is widely accepted. The most abundant inorganic cation in the cytosol is K + , in plant as in animal cells. This cation has probably been selected during evolution because it is less chaotropic than Na + (i.e. more compatible with protein structure even at high concentrations; Clarkson and Hanson, 1980). Its selection might also be due to the fact that in primitive cells, which originated in environmental conditions (seawater) where Na + was more abundant than K + , a straightforward process to energize the cell membrane was to accumulate the less abundant cation and to exclude the most abundant one.In the cell, K + plays a role in basic functions, such as regulation of cell membrane polarization, electrical neutralization of anionic groups, and osmoregulation. Concerning the latter function, K + uptake or release is the usual way through which plant cells control their water potential and turgor. Although toxic at high concentrations, Na + can be used as osmoticum and substituted for K and tissue levels have actually been shown to be essential in plant adaptation to salt stress (Greenway and Munns, 1980;Flowers, 1985;Hasegawa...

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Inventory and Functional Characterization of the HAK Potassium Transporters of Rice

Cited by 290 publications

References 51 publications

Comparative Analysis of the Receptor-Like Kinase Family in Arabidopsis and Rice[W]

Comparative Analysis of the Receptor-Like Kinase Family in Arabidopsis and Rice[W]

Sodium as nutrient and toxicant

Diversity in Expression Patterns and Functional Properties in the Rice HKT Transporter Family

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