Abstract
We have isolated Arabidopsis hma1 mutant by monitoring chlorophyll fluorescence. HMA1 is expected to be involved in the transport of Zn/Co/Pb/Cd. The hma1 showed a growth defect in the presence of 100 μM ZnSO4 and FeSO4-depleted medium. Moreover, the growth defect caused by excess Zn was restored by the addition of excess FeSO4. The photosynthetic parameters of hma1 did not show significant difference from that of WT under normal air condition. In CO2 free air, however, the hma1 showed slightly delayed NPQ, suggesting that limitation of alternative electron transport might result in the decrease of NPQ due to insufficient pH gradient. Even under O2 free condition, the NPQ induction of hma1 was slower than that of WT, indicating that water-water cycle is not involved in the defects in hma1. These results suggest that Fe deficiency caused by excess Zn may lead to alteration of alternative electron transport in hma1.
