Effect of pretreatment with methyl jasmonate on the response of Pisum sativum to salt stress

10-day-old pea seedlings (Pisum sativum L. cv. Ran 1) were supplied with 10(-5) M methyl jasmonate for 3 days before salinization with 30 mmol/L NaCl for 3 and 6 days. Salt stress resulted in an increase of free proline content, CO2 compensation concentration (Gamma), photorespiration (R-p), stomatal resistance (r(s)), and activity of glycolate oxidase (GO) and phosphoglycolate phosphatase (PGP). Net photosynthetic rate (P-N), transpiration (E), protein content and relative water content (RWC) were decreased. Pretreatment with methyl jasmonate helps the plants to counteract the salt stress or for adaptation to it. P-N, RWC and protein content of these seedlings were higher in comparison to NaCl-treated seedlings. Exogenously supplied jasmonate itself plays the role of a stressor that causes typical stress responses - accumulation of free proline, high R-p and Gamma. Pretreatment with methyl jasmonate leads to a decrease of Na+ and Cl- accumulation in the shoot. This protection is discussed with respect to involvement of methyl jasmonate in osmoregulation or osmoprotection based on increased proline accumulation and decreased ion accumulation.