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

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

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290 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)2939-2947
Number of pages9
JournalJournal of Experimental Botany
Volume62
Issue number8
DOIs
Publication statusPublished - 1 May 2011

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