Aluminium reduces sugar uptake in tobacco cell cultures: a potential cause of inhibited elongation but not of toxicity

Abstract

Aluminium is well known to inhibit plant elongation, but the role in this inhibition played by water relations remains unclear. To investigate this, tobacco (Nicotiana tabacum L.) suspension-cultured cells (line SL) was used, treating them with aluminium (50 μM) in a medium containing calcium, sucrose, and MES (pH 5.0). Over an 18 h treatment period, aluminium inhibited the increase in fresh weight almost completely and decreased cellular osmolality and internal soluble sugar content substantially; however, aluminium did not affect the concentrations of major inorganic ions. In aluminium-treated cultures, fresh weight, soluble sugar content, and osmolality decreased over the first 6 h and remained constant thereafter, contrasting with their continued increases in the untreated cultures. The rate of sucrose uptake, measured by radio-tracer, was reduced by approximately 60% within 3 h of treatment. Aluminium also inhibited glucose uptake. In an aluminium-tolerant cell line (ALT301) isogenic to SL, all of the above-mentioned changes in water relations occurred and tolerance emerged only after 6 h and appeared to involve the suppression of reactive oxygen species. Further separating the effects of aluminium on elongation and cell survival, sucrose starvation for 18 h inhibited elongation and caused similar changes in cellular osmolality but stimulated the production of neither reactive oxygen species nor callose and did not cause cell death. We propose that the inhibition of sucrose uptake is a mechanism whereby aluminium inhibits elongation, but does not account for the induction of cell death.

Phytotoxic and genotoxic effect of Aluminum to date palm (Phoenix dactylifera L.) in vitro cultures

“…High Al concentrations decrease the uptake of nutrients, such as Mg, Ca, P, K, Zn and Fe [13]. The inhibition effect of Al on elongation and cell death might involve two phases; the early phase is distinguished by low sugar uptake and inhibition elongation, and the later phase is involved in ROS generation, eventually leading to cell death [4]. ROS production, respiration inhibition and ATP depletion are important events of Al toxicity in plant cells [49].…”

Overexpression of the sucrose transporter gene NtSUT1 alleviates aluminum-induced inhibition of root elongation in tobacco (Nicotiana tabacum L.)

“…During an 18-h Al treatment of tobacco cells in a simple medium containing calcium and sucrose, the cell fresh weight, soluble sugar content and osmolality decreased concomitantly over the first 6 h (earlyphase symptoms) and then remained constant, in contrast to their continual increases in the untreated culture. The production of ROS and callose was observed after 6 h of Al exposure (late-phase symptoms) (Yamamoto et al 2002(Yamamoto et al , 2003Abdel-Basset et al 2010). Thus, we proposed the biphasic Al action and that the inhibition of sucrose uptake by Al could be a primary event to decrease osmolarity, whereby Al represses water uptake and cell elongation.…”

“…In previous studies, we used suspension-cultured tobacco cell lines (SL, BY-2) to elucidate the mechanism of Al cytotoxicity. Cells in the logarithmic growth phase showed symptoms similar to those of roots, such as inhibited cell elongation and cell death (physiological responses) as well as production of reactive oxygen species (ROS) and callose (biochemical responses) (Yamamoto et al 2002(Yamamoto et al , 2003Abdel-Basset et al 2010). In those studies, cell death was evaluated by several biological markers such as respiration inhibition, loss of plasma membrane integrity (monitored by staining with Evans blue or fluorescein diacetate; FDA), and growth arrest.…”

“…Cell elongation depends on three events: water uptake, loosening of the cell wall and synthesis of cell wall constituents. The inhibitory effect of Al ions on cell elongation was investigated in tobacco cells (line SL), focusing on water relations (Abdel-Basset et al 2010). During an 18-h Al treatment of tobacco cells in a simple medium containing calcium and sucrose, the cell fresh weight, soluble sugar content and osmolality decreased concomitantly over the first 6 h (earlyphase symptoms) and then remained constant, in contrast to their continual increases in the untreated culture.…”

The Role of Nanoscience and Technology in Medicine and Agriculture: Awareness Implication for Health Systems and Food Safety Issues

“…The application of NPs have been used in a number of ways to reduce disease levels and prevent the development and spread of pathogens, thus preserving yield and quality crop products. Abdelbasset et al [8] reported that both chitin and chitosan nanoparticles have demonstrated antiviral, antibacterial, and antifungal properties, and have been explored for many agricultural uses.…”