Figure 4.

Cd induces Fe-deficiency stress responses in maize. A, RNA gel-blot analysis of ZmYS1 expression in roots from hydroponically grown plants that were precultured for 20 d in absence of Fe or in the presence of 100 μm Fe(III)-EDTA before addition of 0, 1, 5, or 25 μm CdCl₂ for 12, 24, or 48 h to the nutrient solution. Plants were harvested at the same time, and total RNA from roots was used for hybridization to the complete ORF of ZmYS1. Ethidium bromide-stained gel blots are shown as a control. B, Rate of DMA release within 6 h from roots of 10-d-old maize plants grown under axenic conditions. The plants were incubated in the absence or presence of 25 μm Cd for 24 h before being transferred to ultrapure water for collection of the exudates. Bars indicate means ± sd (n = 5).