title: Major genes for Na+ exclusion, Nax1 and Nax2 (wheat HKT1;4 and HKT1;5), decrease Na+ accumulation in bread wheat leaves under saline and waterlogged conditions.
abstract: Two major genes for Na(+) exclusion in durum wheat, Nax1 and Nax2, that were previously identified as the Na(+) transporters TmHKT1;4-A2 and TmHKT1;5-A, were transferred into bread wheat in order to increase its capacity to restrict the accumulation of Na(+) in leaves. The genes were crossed from tetraploid durum wheat (Triticum turgidum ssp. durum) into hexaploid bread wheat (Triticum aestivum) by interspecific crossing and marker-assisted selection for hexaploid plants containing one or both genes. Nax1 decreased the leaf blade Na(+) concentration by 50%, Nax2 decreased it by 30%, and both genes together decreased it by 60%. The signature phenotype of Nax1, the retention of Na(+) in leaf sheaths resulting in a high Na(+) sheath:blade ratio, was found in the Nax1 lines. This conferred an extra advantage under a combination of waterlogged and saline conditions. The effect of Nax2 on lowering the Na(+) concentration in bread wheat was surprising as this gene is very similar to the TaHKT1;5-D Na(+) transporter already present in bread wheat, putatively at the Kna1 locus. The results indicate that both Nax genes have the potential to improve the salt tolerance of bread wheat.
authors.affiliation: CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia.
authors.forename: Richard A
authors.initials: RA
authors.lastname: James
authors.forename: Carol
authors.initials: C
authors.lastname: Blake
authors.forename: Caitlin S
authors.initials: CS
authors.lastname: Byrt
authors.forename: Rana
authors.initials: R
authors.lastname: Munns
mesh_terms: D001315:Australia; D001939:Bread; D002245:Carbon Dioxide / Q000378:metabolism; D018744:DNA, Plant / Q000235:genetics; D055868:Floods; D017343:Genes, Plant / Q000235:genetics; D010641:Phenotype; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D054046:Plant Stomata / Q000187:drug effects / Q000502:physiology; D011188:Potassium / Q000378:metabolism; D054712:Salinity; D012964:Sodium / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology; D014908:Triticum / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*
chemical_list: D018744:DNA, Plant; D010940:Plant Proteins; D002245:Carbon Dioxide; D012965:Sodium Chloride; D012964:Sodium; D011188:Potassium