Distribution characteristics of aluminum in Pinus massoniana under different concentrations of aluminum treatments

Abstract

The distribution and subcellular localization of toxic metal ions in plant tissues are of great significance for plants to cope with metal stresses, which could provide valuable insights into the mechanisms underlying plant metal tolerance. To explore the distribution of aluminum (Al) at the subcellular level after entering Pinus massoniana, four aluminum concentrations of 0, 0.5, 1.0, 2.0 mmol·L-1 were set up in this study. The growth status of P. massoniana and the distribution characteristics of aluminum at the subcellular level under different Al concentrations were studied by pot experiment. The results were as follows: (1) P. massoniana exhibited significant growth enhancement under 0.5 mmol·L-1 Al treatment, and the biomass, seedling height, root length, as well as the number of lateral roots were all significantly promoted. However, higher Al concentrations (≥1 mmol·L-1) led to diminished growth promotion effects and inhibited root growth and cell viability in P. massoniana root tips. (2) Translocation of Al from roots to shoots in P. massoniana was limited. The absorbed Al was mainly deposited in the roots (P<0.05), although the accumulation of Al in the shoots increased along with the Al concentration increased. (3) At the subcellular level, different Al concentrations affected the proportions of absorbed Al deposited in cell walls and vacuoles. Under both 0.5 and 1.0 mmol·L-1Al treatments, the proportions of Al in both the cell walls and vacuoles of roots or shoots were all at higher levels compared with other cell components, and there was no significant difference between the Al contents of cell walls and vacuoles. However, at high Al concentration (2.0 mmol·L-1), a majority of deposited Al was found on the cell walls, accounting for 55% and 70% in root and shoot cells, respectively. In contrast, the Al contents in the organelles and cytoplasm maintained low levels of Al concentration treatments, which mitigated the adverse effects of Al on cellular functions. In summary, the presented results suggest that P. massoniana effectively adapted to Al stress through coordinated distribution and subcellular localization mechanisms for absorbed Al. This evokes the needs of further investigation of the adaptation mechanisms of P. massoniana to Al stress from both the cellular and molecular levels.

Keywords

• pinus massoniana
• aluminum (al)
• subcellular components
• cell wall
• distribution characteristics