Fig. 10

Model explaining changes in the expression pattern of endogenous metal homeostasis genes in AtHMA4-expressing plants, that contribute to the generation of the phenotype of transformants. a Effect of ectopic expression of 35S::AtHMA4 on cellular Zn status of the host plant, followed by modification of the expression pattern of endogenous homeostasis genes - starting point for the current research. b Molecular consequences of altered Zn status due to constant export activity of AtHMA4 in transgenic tomato (TR) exposed to 0.5 μM Zn, 5 μM Zn and to 0.5 μM Zn + 0.25 μM Cd: changes in the expression pattern of endogenous metal-homeostasis and ethylene genes in TR vs wild-type (WT) are Zn-supply dependent, Cd-dependent and tissue-specific; Exposure of WT to lower/higher Zn in the medium generates a Zn-status-specific transcriptome background; In TR plants, a combination of a given Zn-status-specific generated molecular background (resulting from the Zn level in the medium) with changes in the Zn status resulting from the constant export activity of AtHMA4, contributes to the detected differences in the tissue-specific expression pattern of the examined genes. The presence of Cd changes also the tissue-specific expression pattern in TR in a fashion different from that of WT. EC- epidermis + cortex; S – stele