Identifying the genetic basis of new components of salinity tolerance in barley

Abstract

Barley is a resilient crop that performs better than other cereal plants under abiotic stress conditions, including salinity stress. The understanding of salinity tolerance in crops is a major milestone to increase yield in areas affected by soil salinity. In barley, some components of salinity tolerance have been elucidated, (e.g. HVP10, which is involved in tissue tolerance), yet little research has explored the discovery of other components contributing to salinity tolerance. In this PhD project, a forward genetics approach was used, whereby two barley populations were phenotyped under controlled and field conditions for salinity tolerance. The first population is a diversity panel of two-row European spring barley, and the second population is a nested association mapping barley population with wild donors from the Fertile Crescent. The use of non-destructive high-throughput experiments conducted under controlled conditions provided insight into the understudied shoot ion-independent component of salinity tolerance. In addition, the previously known association HvHKT1;5 was detected under controlled conditions. In parallel, the field experiments increased our understanding of new components of salinity tolerance, such as the maintenance of yield and yield-related traits under saline conditions. This strategy was successful with the identification of a locus on chromosome 2H (140-145 cM), where the allele from one of the wild donors of the nested association mapping population increased yield under saline conditions in the field. When re-evaluating lines homozygous at the 2H locus, ear length, ear number per plant, yield and harvest index were all significantly higher under saline conditions for the lines carrying the wild allele. Furthermore, another interesting locus on chromosome 7H that was responsive to salt treatment and co-localized with HVP1 was identified using the diversity panel population. Loci with known flowering genes were also shown to be involved in salinity tolerance. To conclude, this PhD project shed more light on the genetic mechanisms of salinity tolerance in barley, a knowledge that can benefit breeding programs and can be extended to other crops such as wheat.