Germination and growth of Atriplex prostrata and Plantago coronopus: Two strategies to survive in saline habitats

Abstract

We investigated the effects of NaCl on germination, germination rate, growth, proline content, polyamine levels (putrescine, spermidine and spermine) and total polyamines in Atriplex prostrata and Plantago coronopus. The seeds collected from Brujuelo (salt marshes, Jaén, southern Spain) were germinated under control (water) and saline conditions (50, 100, and 200mM NaCl) for 20days at 25°C. Salinity decreased germination percentage and the germination rate in A. prostrata, and P. coronopus with increasing salt concentrations. In seedlings at day 6 and 10 of the experiment, both the length and fresh mass increased in A. prostrata for all saline treatments with respect to control, whereas in P. coronopus, only fresh mass increased with 50 and 100mM NaCl, indicating its lower salinity tolerance. With respect to proline, the maximum increase occurred with 200mM NaCl in A. prostrata; however in P. coronopus the values were low and without significant differences between treatments. The polyamine levels changed, in P. coronopus spermidine and spermine increased with salt, while in A. prostrata putrescine and spermidine decreased. These results indicate that the increase of proline was accompanied by a decrease of total polyamines (putrescine+spermidine+spermine) in A. prostrata while P. coronopus had high total polyamine levels with low values of proline, demonstrating that these plants use different strategies to adapt to saline environments.