biologia plantarum

Biologia plantarum 50:61-68, 2006 | DOI: 10.1007/s10535-005-0075-9

Antioxidant and anatomical responses in shoot culture of the apple rootstock MM 106 treated with NaCl, KCl, mannitol or sorbitol

A. N. Molassiotis^1,*, T. Sotiropoulos², G. Tanou¹, G. Kofidis³, G. Diamantidis¹, E. Therios¹

¹ School of Agriculture, Aristotle University of Thessaloniki, Thessaloniki, Greece

² NAGREF, Pomology Institute, Naousa, Greece

³ Department of Botany, School of Biology, Aristotle University, Thessaloniki, Greece

To determine whether the major influence of high salinity is caused by the osmotic component or by salinity-induced specific ion toxicity, we compared the effects of mannitol, sorbitol, NaCl and KCl (all in concentratuions corresponded to osmotic potential -1.0 MPa) on the antioxidant and anatomical responses of the apple rootstock MM 106 explants grown in the Murashige and Skoog (MS) medium. All the compounds had a significant influence on explant's mineral composition and reduced the leaf water content, whereas mannitol and salts decreased chlorophyll (Chl) content and increased proline content. Superoxide dismutase (SOD), peroxidase (POD) and non-enzymatic antioxidant activities as well as H₂O₂ content were increased in the leaves and stems. In addition, in the leaves of explants exposed to NaCl an additional Mn-SOD isoform was revealed, while specific POD isoforms were detected in the leaves and stems treated with NaCl or KCl. However, catalase activity was depressed in the salt-treated leaves. At the ultrastructural level, the NaCl-treated leaves had the thickest lamina, due to an extensive increase of the size of epidermal and mesophyll cells. Also, an increase of the relative volume of the intercellular spaces in response to NaCl was observed. The results suggest that Na accumulation is the first candidate for the distinct antioxidant and anatomical responses between saline and osmotically generated stress in the MM 106 explants.

Keywords: catalase; chlorophyll; Malus domestica; peroxidase; polyacrylamide gel electrophoresis; proline; superoxide dismutase

Subjects: antioxidants, antioxidative enzymes; catalase; chlorophyll a,b; mannitol; nutrient medium, Murashige and Skoog; peroxisome; rootstock; sorbitol; superoxide dismutase (SOD)

Received: August 13, 2004; Accepted: March 30, 2005; Published: March 1, 2006  Show citation