Journal Article

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

James, Richard A., Blake, Carol, Byrt, Caitlin S., Munns, Rana

2011

Overview

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.

• Publisher: Oxford University Press
• Subject: Australia / Biological and medical sciences / Bread / Carbon Dioxide / Carbon Dioxide - metabolism / crossing / DNA, Plant / DNA, Plant - genetics / drug effects / Durum wheat / flooded conditions / Floods / Fundamental and applied biological sciences. Psychology / Genes / Genes, Plant / Genes, Plant - genetics / genetics / Hexaploidy / leaf blade / Leaves / loci / major genes / marker-assisted selection / metabolism / pharmacology / Phenotype / physiology / Plant Leaves / Plant Leaves - drug effects / Plant Leaves - genetics / Plant Leaves - metabolism / Plant physiology and development / Plant Proteins / Plant Proteins - genetics / Plant Proteins - metabolism / Plant Stomata / Plant Stomata - drug effects / Plant Stomata - physiology / Plants / Potassium / Potassium - metabolism / RESEARCH PAPER / Salinity / Salt tolerance / Sodium / Sodium - metabolism / Sodium Chloride / Sodium Chloride - pharmacology / Soil salinity / tetraploidy / transporters / Triticum / Triticum - drug effects / Triticum - genetics / Triticum - metabolism / Triticum aestivum / Triticum turgidum subsp. durum / Wheat / Xylem