Abstract
To elucidate mechanism(s) of aluminum (Al)-induced growth inhibition, the effects of Al on sucrose uptake and water uptake were investigated in tobacco cells. Cells were treated without (control) or with Al in a simple calcium solution containing 3% sucrose (pH 4.5-5.0). Control cells exhibited sucrose and water uptake continuously, which was inhibited by Al immediately. PCMBS and CCCP also inhibited sucrose uptake in control cells, indicating that Al inhibits H+-dependent sucrose transporter. The inhibition of sucrose uptake by Al was reversible in Al-free nutrient medium, but became gradually irreversible after 9-h exposure, together with increases in respiration inhibition, ATP depletion, reactive oxygen species production and loss of growth capability. These results suggest that Al inhibits sucrose uptake, which is immediately linked to water uptake inhibition and cell elongation inhibition, then, after prolonged sucrose starvation, decreases in mitochondrial functions lead to irreversible cell death process.
