A field trial was conducted to identify the key factors affecting intraspecific variation in the cadmium (Cd) content in the grain of winter wheat. Three wheat cultivars with low Cd accumulation and two wheat cultivars with high Cd accumulation were planted. The Cd accumulation and transport and ionomic traits were examined in different organs of the tested wheat cultivars. Additionally, correlation analysis and principal component analysis were used to identify the key plant organs, translocation pathways, and elements that determine the intraspecific variation in the Cd content in wheat grain. The results showed that the bioaccumulation factors of Cd in glume, rachis, internode 1, and node 1, as well as the transport factors of Cd from rachis to grain, from rachis to glume, from internode 1 to rachis, and from node 1 to internode 1, were significantly correlated with Cd bioaccumulation factors in grain. The above-mentioned bioaccumulation factors and transport factors of Cd made a great contribution to the principal components that could discriminate between the wheat cultivars with low and high Cd accumulation and were significantly different among cultivars. Therefore, glume, rachis, internode 1, and node 1 were the key organs affecting the genotype differences in Cd content in wheat grain, and Cd translocation from rachis to grain, from rachis to glume, from internode 1 to rachis, and from node 1 to internode 1 were the key pathways controlling the variety differences in Cd accumulation in wheat grain. The analysis of wheat ionome showed that the bioaccumulation factors of Mg and Mn in the key organs and the transport factors of Mo, Cr, and Pb in the key transport pathways were significantly correlated with the bioaccumulation factor of Cd in wheat grain and contributed greatly to the differentiation between the wheat cultivars with low and high Cd accumulation in the principal component analyses. Thus, in the above-mentioned key organs and transport pathways, Mg, Mn, Mo, Cr, and Pb were the key elements affecting the genotype differences in Cd content in wheat grain.
Keywords: bioaccumulation factor; cadmium(Cd); genotype differences; ionome; transport factor; wheat.