Fig. 4
Variation of FtPK controls salt resistance differences between north and south populations of Tartary buckwheat. A Selective sweeps identified through comparisons between SL and NL using XP-CLR (cross-population composite likelihood-ratio test). The dashed line represents the top 5% of values therefore scores in these regions were regarded as selective sweeps. B Manhattan plot of GWAS signals for salt resistance in Tartary buckwheat accessions. The dashed line represents the threshold (-log10P=5). C Schematic diagram of FtPK gene structure. Two SNPs in the promoter of FtPK are marked with red letters and result in haplotypes (Hap) 1 and 2. D Box plots show salt resistance in two haplotypes (Hap). nHap-1 = 13, nHap-2 = 120. P value was calculated using two-tailed t-tests. E The expression level of FtPK in accessions with the two haplotypes. The error bars indicate the ± s. d, n = 6. The P value was calculated using one-way ANOVA. (F) Transcription activity of FtPK promoters with two haplotypes. G Differentiation salt resistance of accessions among HW, NL and SL groups. nHW = 7, nNL = 93, nSL = 51. Significant differences were tested using two-tailed t-tests. *, P < 0.05. H Frequencies of the two haplotypes in the HW, NL and SL groups. I Confocal microscope image showing nuclear localization of FtPK-GFP fusion protein upon transient expression in N. benthamiana leaf cells. Scale bars, 10 µm. J Phenotypes of Arabidopsis lines heterologously expressing FtPK and subjected to salt stress. K Root length of Arabidopsis lines heterologously expressing FtPK and subjected to salt stress. Significant differences were tested using two-way ANOVA with Tukey HSD test. There was an effect of treatment (F = 11.044, df = 1, P = 0.004) and an effect of genotype (F = 4.478, df = 3, P = 0.018)