Early growth stages salinity stress tolerance in CM72 x Gairdner doubled haploid barley population

Abstract

A doubled haploid (DH) population of barley (Hordeum vulgare L.) generated from salinity tolerant genotype CM72 and salinity sensitive variety Gairdner was studied for salinity stress tolerance at germination, seedling emergence and first leaf full expansion growth stages. Germination study was conducted with deionized water, 150 mM and 300 mM NaCl treatments. Seedling stage salinity tolerance was conducted with three treatments: control, 150 mM NaCl added at seedling emergence and first leaf full expansion growth stages. Results from this study revealed transgressive phenotypic segregations for germination percentage and biomass at seedling stage. Twelve QTL were identified on chromosomes 2H–6H each explaining 10–25% of the phenotypic variations. A QTL located at 176.5 cM on chromosome 3H was linked with fresh weight per plant and dry weight per plant in salinity stress induced at first leaf full expansion growth stage, and dry weight per plant in salinity stress induced at seedling emergence. A stable QTL for germination at both 150 and 300 mM salinity stress was mapped on chromosome 2H but distantly located from a QTL linked with seedling stage salinity stress tolerance. QTL, associated markers and genotypes identified in this study play important roles in developing salinity stress tolerant barley varieties.

Genome-Wide Association Study of Salinity Tolerance During Germination in Barley (Hordeum vulgare L.)

“…This study used a modified method based on those of Bliss et al (1986) and Angessa et al (2017) to determine salinity tolerance during germination. Barley seeds were surface-sterilized for 5 min using 10% sodium hypochlorite, and then rinsed with sterile water.…”

“…The germination percentage (G%) was calculated following the equation of Adjel et al (2013), namely, G% = GS/TS×100%, where GS is the total number of germinated seeds, and TS is the total number of incubated seeds. The tolerance index was subsequently calculated as follows (Angessa et al, 2017), TI% = G t %/G c %×100%, where G t % is the percentage of seeds germinated in the salt treatment, and G c % is the percentage of seeds germinated in deionized water.…”

“…Different methods of screening for salinity tolerance have been proposed, including non-stress conditions (Betran et al, 2003), stress conditions, and midway (non-stress and stress) (Ashraf et al, 2015). Selection criteria for salinity stress tolerance include the capacity of germplasm to produce high yields under stress (Rosielle and Hamblin, 1981), the stress susceptibility index being the degree of damage caused (Fischer and Maurer, 1978), and the stress tolerance index, being the percentage of yield under stress and non-stress conditions in the same germplasm (Angessa et al, 2017).The stress tolerance index is not suitable for genotypes that produce low yields under nonstress conditions (Kumar et al, 2014); it can be used to identify genotypes that produce high yields under both stress and nonstress conditions (Askari et al, 2016). Allel et al (2019) evaluated various indices for salinity tolerance screening and confirmed that the salt-tolerance index is a better selection tool for highly salt-tolerant and productive barley genotypes under salinity, as reported by others (Ali et al, 2007;Shahzad et al, 2012;Senguttuvel et al, 2016).…”

“…At this stage, several different loci control salinity tolerance (Mano and Takeda, 1997). Angessa et al (2017) reported transgressive phenotypic segregation for germination rate and biomass at the seedling stage using a doubled haploid (DH) barley population derived from a CM72 Gairdner cross, with both traits controlled by different QTLs on chromosomes 2H and 3H, respectively. At the germination stage, Mano and Takeda (1997) reported 17 QTLs controlling abscisic acid (ABA) response on chromosomes 2H, 3H, 1H, and 5H in Steptoe Morex DH lines, and 9 QTL on 2H and 5H in a Harrington TR306 DH population.…”

“…There is little information linking the QTLs reported for salinity tolerance at the germination stage to specific genes and genetic mechanisms (Mano and Takeda, 1997;Hanen et al, 2014;Angessa et al, 2017). Genome-wide association (GWAS) studies are increasingly used to discover and explain the genetic basis of agronomic traits that are often controlled by many genes of small magnitude, such as germination (Shi et al, 2017;Hazzouri et al, 2018;Naveed et al, 2018;Yu et al, 2018).…”