Effect of pre-treatment with ethanolamine on the response of Helianthus annuus L-to salt stress

The accumulation of compatible solutes is one of the strategies that plants have developed to tolerate salt stress. Proline and betaine are the main m etabolites that accumulate in various species of higher plants in response to salt stress. In Helianthus annuus L., pre-treatment of seeds with ethano lamine led to enhanced seedling tolerance to conditions of saline stress du ring germination, as evidenced by the greater growth of pretreated seedling s (EAS group) versus untreated seedlings (S group), evaluated through such parameters as length, water and chlorophyll content. During the germination period, a considerable increase was observed in proline levels (up to 300% ) in seedlings subjected to saline stress, whereas in the EAS group, the pr oline increment was much smaller (20%). Starting from the fourth day of ger mination, betaine levels in seedlings pretreated with ethanolamine and then with water (EAW group) and in EAS showed a significant increase versus C ( control) and S seedlings, possibly because such a precursor promotes betain e biosynthesis. This could be responsible for the enhanced growth observed in EAS versus S seedlings, as well as for preventing the decrease in chloro phyll content in the EAS group. The accumulation of betaine seems to correl ate with the greater tolerance of these seedlings against stress induced by sodium chloride.