Effect of salinity on ionic dise quilibrium and cardinolids synthesis in adonis autumnalis

ABSTRACT

Salinity is involved in decline of plant production in arid and semi-arid lands. It is believed that Ca[2+] maintains the structural integrity of the plasmo membrane by cross linking the negatively charged head groups of the plasmo membrane. In this paper we study the effect of salinity on cardinolid synthesis in Adonis autumnalis plants. Plants of Adonis autumnalis [Aleppo] were grown in three salinity conditions 25, 50 and 100 mM NaCl, during 22 weeks. Leaves of stressed plants had a higher K[+] and Na[+] contents and a lower Ca content than leaves of control plants, K[+]/Na[+] ratio of leaves of stressed plants become a lower than 1 when the senescence was started. Na[+]/Ca[2+] ratio became a higher the higher the salinity conditions were and the longer the time of stress. The roots of stressed plants had lower K[+] content in higher salinity and as longer the time of stress. The Na[+] content of roots of stressed plants was higher than the Na[+] content in roots of control plants, but decreased at the end of experiment due to necrosis and loss of young parts of roots. Ca[2+] content in roots was lower as the salinity stress was higher. The Na[+]/Ca[2+] ratio in roots was maintained low, due to necrosis and loss of young parts of roots. Salinity and ionic disequilibrium did not interfered significantly on cardinolids metabolism. The content of cardinolids did not changed significantly in salinity conditions until the death of the plants. The slight ionic imbalance, which reaches weak levels of salinity, leads to the activation of the cadiotonic glycosides accumulation in the leaves of Adonis autumnalis, and in doing so, it leads to increasing the concentrations of the cardionolides in the leaves and roots of Adonis autumnalis which have been treated at at the salinity of 25mM.