Descripción: |
Coffea arabica is a woody species that grows in acid soils, where aluminum is available andmay affect growth and
productivity. To determine the effect of aluminumon primary root growth of C. arabica cv. Typica, seedlings were
exposed over 30 days to different concentrations of AlCl3 (0, 100, 300 and 500 μM) in vitro. The aluminumeffect on
primary root growth was dose-dependent: low aluminum concentrations (100 and 300 μM) stimulated primary
root growth (6.98 ± 0.15 and 6.45 ± 0.17 cm, respectively) compared to the control (0 μM; 5.24 ± 0.17 cm),
while high concentrations (500 μM) induced damage to the root tips and inhibition of primary root growth
(2.96 ± 0.28 cm). Aluminum (100 μM) also increased the K and Ca contents around 33% and 35% in the coffee
roots. It is possible that aluminum toxicity resides in its association with cell nuclei in the meristematic region of
the root. Additionally, after 30 days of treatment with aluminum, two different effects could be observed on
phospholipase C (PLC) activity. In shoots, aluminum concentrations ≥300 μM inhibited more than 50% of PLC
activity. In contrast, in roots a contrasting behavior was determined: low (100 μM) and toxic concentrations
(500 μM) increased the activity of PLC (100%). These results suggest the possible involvement of the
phosphoinositide signal transduction pathway, with the phospholipase C enzyme participating in the beneficial
and toxic effects of aluminum in plants. |