Assessment of the salt tolerance of wheat genotypes during the germination stage based on germination ability parameters and associated SSR markers

Abstract

Although the germination stage accounts for a very short period of a plant's life cycle, it involves numerous mechanisms and multistage processes that potentially differ among genotypes under salt stress. Therefore, we hypothesized that the parameters controlling the water uptake pattern and α-amylase activity during the seed germination process could be helpful for assessment the salt tolerance of wheat genotypes at the early growth stage. Genotypic differences in the germination ability parameters and α-amylase activity were assessed for seven wheat cultivars under normal and salt stress conditions at the molecular marker level using 30 simple sequence repeat (SSR) markers linked to salt tolerance. Results found that genotypic variations in the water uptake pattern were appeared at the late stage of phase II under both salinity levels and more obviously during phase III. Genotypic variations were observed in the germination time (GT), which was delayed by increasing salinity levels. The α-amylase activity and GT were positively and negatively correlated, respectively, with each time of water uptake rate. Significant correlation (r = 0.49, P = 0.026) was observed between similarity coefficients of germination ability parameters and SSR data based on the Mantel test. Among the 24 SSR markers, which showed polymorphism, Cdf 9, Cdf 46, Cdf 49, Wmc 503, and Gwm 312 were associated with almost germination ability parameters (R 2 ranged from 0.43 to 0.95). Therefore, based on the molecular marker-phenotypic trait association at germination stage, assessment of salt tolerance in many wheat genotypes in a relatively short time could be conceivable.

Morphological and Genetic Diversity within Salt Tolerance Detection in Eighteen Wheat Genotypes

“…High parameter values (TNB, NPB, PPB%, PIC, and DP%) were registered, which showed that the used SSR markers are helpful in detecting the genetic variability of wheat genotypes (Table 4). We obtained 42 alleles in total, with an average of 2.33 alleles and a PIC value greater than 0.50, indicating the ability of these markers to analyze the genetic variability of wheat genotypes, which were consistent with the results obtained in wheat genotypes using different SSR markers by [30,32,44]. These findings suggest that the tested markers are informative and capable of detecting salt-tolerant genotypes.…”

“…A spectrophotometer (Thermo scientific, Wilmington, DE, USA) was used to measure the DNA concentration at 260 nm, and the extract was electrophoresed on 0.8% agarose to ensure the quality. After that, the refined DNA was standardized at 25 ng µL-1, and the final concentration was kept at −20 • C. The 43 SSR markers used in this study were selected from previous studies [30][31][32]44] or the Graingenes website (http://wheat.pw.usda.gov/ggpages/maps.shtml; accessed on 10 November 2019), as they have been linked with salt tolerance in wheat (Table S2). For each 20 µL reaction, the PCR reaction mixture contained 8 µL nuclease-free water, 10 µL 1× GoTaq green master mix (Promega Corporation, Madison, Wisconsin, USA), 0.5 µL primer, and 1.5 µL 25 ng of genomic DNA.…”

“…SSRs are powerful markers used in assessing polymorphisms and the degree of genetic variation of many plant species, including wheat [70]. In this study, 43 different SSR markers were tested and selected for their association with salt tolerance genes in wheat [29,32,44]. Here, we evaluated 23 SSR markers that generated polymorphisms to decipher their discriminating capacity between the salt-tolerant genotypes through identifying allele markers that are associated with each genotype.…”

“…According to the Mantel test, the clustering pattern in this study is caused by both the genetic and morphological distances, as a significant positive correlation was observed (r = 0.514, p < 0.0001, alpha = 0.05). In addition, the SSR markers were successfully used for gene tagging or used in marker-assisted selection for agronomic traits [44,77].…”

Effects of Salinity on Seed Germination and Early Seedling Stage

“…Based on these three phases, the inhibition of seed germination or delaying in germination time under salinity stress may be generally ascribed to osmotic stress in the phase I and ionic stress in the phase II. Osmotic stress and ionic stress interact together to inhibit or delay germination of seed during the phase III [88].…”