title: Expression of LeNHX isoforms in response to salt stress in salt sensitive and salt tolerant tomato species.
abstract: In general, wild tomato species are more salt tolerant than cultivated species, a trait that is related to enhanced Na(+) accumulation in aerial parts in the wild species, but the molecular basis for these differences is not known. Plant NHX proteins have been suggested to be important for salt tolerance by promoting accumulation of Na(+) or K(+) inside vacuoles. Therefore, differences in expression or activity of NHX proteins in tomato could be at the basis of the enhanced salt tolerance in wild tomato species. To test this hypothesis, we studied the expression level of four NHX genes in the salt sensitive cultivated species Solanum lycopersicum L. cv. Volgogradskij and the salt tolerant wild species Solanum pimpinelifolium L in response to salt stress. First, we determined that in the absence of salt stress, the RNA abundance of LeNHX2, 3 and 4 was comparable in both species, while more LeNHX1 RNA was detected in the tolerant species. LeNHX2 and LeNHX3 showed comparable expression levels and were present in all tissues, while LeNHX4 was expressed above all in stem and fruit tissues. Next, we confirmed that the wild species was more tolerant and accumulated more Na(+) in aerial parts of the plant. This correlated with the observation that salt stress induced especially the LeNHX3 and LeNHX4 isoforms in the tolerant species. These results support a role of NHX genes as determinants of salt tolerance in tomato, inducing enhanced Na(+) accumulation observed in the wild species when grown in the presence of NaCl.
authors.affiliation: Department of Biochemistry, Cellular and Molecular Biology of Plants, Estación Experimental del Zaidín, CSIC, 18008 Granada, Spain.
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Gálvez
authors.forename: Mourad
authors.initials: M
authors.lastname: Baghour
authors.forename: Gangping
authors.initials: G
authors.lastname: Hao
authors.forename: Olivier
authors.initials: O
authors.lastname: Cagnac
authors.forename: María Pilar
authors.initials: MP
authors.lastname: Rodríguez-Rosales
authors.forename: Kees
authors.initials: K
authors.lastname: Venema
mesh_terms: D005638:Fruit / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D018551:Solanum lycopersicum / Q000187:drug effects / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D010802:Phylogeny; D035261:Plant Components, Aerial / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D010940:Plant Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism*; D055051:Salt-Tolerant Plants / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics / Q000378:metabolism*; D013312:Stress, Physiological; D013997:Time Factors
chemical_list: D010940:Plant Proteins; D020033:Protein Isoforms; D018749:RNA, Plant; D017923:Sodium-Hydrogen Exchangers; D012965:Sodium Chloride; D012964:Sodium