Proline accumulation in three closely related Salsola L. taxa

Abstract

Halophytes, gypsicoles and serpentinicoles are adapted to specialized edaphic conditions at arid and semi-arid regions. These arid and semi-arid areas possess physical and chemical stress factors for all plants. For these plants, one of the most important parameter that provides stress tolerance is the proline accumulation. Proline is a water-soluble amino acid generally accumulated under stress and behave like an indicator for adaptation of plants against extreme conditions. In this study, the amounts of proline accumulation in three different taxa, Salsola boissieri subsp. serpentinicola, Salsola boissieri subsp. boissieri and Salsola turcica, were determined. These taxa are phylogenetically close to each other but adapted to different soil types. The highest proline accumulation measured in leaves of S. turcica with the value of 2.510 ± 0.020 µmol g-1 FW and the lowest accumulation measured in leaves of S. boissieri subsp. serpentinicola with the value of 0.996 ± 0.024 µmol g-1 FW. As a result of these proline accumulations, it can be concluded that the high amount of proline accumulation in halophytic S. turcica is a response against stress conditions but the low proline accumulation of S. boissieri subsp. serpentinicola means this species may have other adaptations against the stress factors that caused by serpentinicolous soils. Both of the studied taxa accumulate proline and the findings show that proline accumulation can be a marker in the assessment of stress tolerance of Salsola species.