Differences in Mn uptake and subcellular distribution in different barley genotypes as a response to Cd toxicity.

A hydroponics experiment was carried out in greenhouse to study the genotypic differences in Mn uptake and subcellular distribution in response to Cd toxicity. Increased Cd level in medium caused a significant reduction in plant height and fresh weight, and ZAU3 and Wumaoliuling being the least and the most affected genotypes, respectively. There was a marked difference in proportion of Mn accumulation in different fractions relative to the total Mn amount in tissues among the 4 fractions, with the soluble fraction FIV showing the largest proportion in shoots, followed by organelle containing fraction (FIII), while cell wall (FI) and chloroplasts FII being the smallest. Meanwhile, Cd significantly increased FIII Mn accumulation proportion, but decreased FIV proportion, with significant genotypic difference of Wumaoliuling being the least increase in FIII and the greatest decrease in FIV among the 4 genotypes. In roots, the major pool of Mn content was FI, FIV, and FIII, and Cd induced no significant changes. Furthermore, Cd caused a significant reduction in subcellular Mn concentration of FI and FIV fractions in shoots and the 4 fractions in roots, with more pronounced in Cd-sensitive cultivar Wumaoliuling in root FII, FIII and FIV, and shoot FI, FII, and FIII, while little difference in both Mn concentrations of root FI, and shoot FIV.