Genetics of Na exclusion and salinity tolerance in Afghani durum wheat landraces.

BACKGROUND

Selecting for low concentration of Na in the shoot provides one approach for tackling salinity stress that adversely affects crop production. Novel alleles for Na exclusion can be identified and then introduced into elite crop cultivars.

RESULTS

We have identified loci associated with lower Na concentration in leaves of durum wheat landraces originating from Afghanistan. Seedlings of two F populations derived from crossings between Australian durum wheat (Jandaroi) and two Afghani landraces (AUS-14740 and AUS-14752) were grown hydroponically and evaluated for Na and K concentration in the third leaf. High heritability was found for both third leaf Na concentration and the K/Na ratio in both populations. Further work focussed on line AUS-14740. Bulk segregant analysis using 9 K SNP markers identified two loci significantly associated with third leaf Na concentration. Marker regression analysis showed a strong association between all traits studied and a favourable allele originating from AUS-14740 located on the long arm of chromosome 4B.

CONCLUSIONS

The candidate gene in the relevant region of chromosome 4B is likely to be the high affinity K transporter B1 (HKT1;5-B1). A second locus associated with third leaf Na concentration was located on chromosome 3BL, with the favourable allele originating from Jandaroi; however, no candidate gene can be identified.