Changes in the Membrane Phospholipid Composition of Tomato Seeds accompanying Loss of Germination Capacity caused by Controlled Deterioration

Abstract

Controlled deterioration caused a progressive decrease in total phospholipid content of tomato (Lycopersicon esculentum Mill) seeds. These losses were not confined to the embryo. Low temperature pre-sowing treatments, shown to improve the rate, but not the final germination capacity of artificially aged seeds, had no ameliorating effect on total phospholipid (PL) losses following the first 72 h of germination of unaged seeds. There was a significant increase in the amount of phospholipid present in both treated and untreated samples and significant changes in composition of the PL fraction. Phosphatidyl choline (PC) was identified as the major phospholipid class present, levels decreasing during controlled deterioration. Low temperature pre-sowing treatment had no significant effect on phospholipid composition of viable aged and unaged seeds. This indicates that losses of viability which accompany controlled deterioration are related to losses of PC from the membranes, but decreases in germination rates are caused by other, as yet undefined changes in seed metabolism.