Plasma Membrane H+-ATPase during Embryo Dormancy and Dormancy Release in Horse Chestnut Seeds

Horse chestnut seeds harvested in October were exposed to wet cold stratification for 14 weeks, thus providing a way for seeds to overcome the state of deep physiological dormancy and acquire the ability to germinate. During first 5-6 weeks, a small portion of seeds germinated hardly and slowly while later on seeds germinated more uniformly and rapidly. The experiments with facilitated water supply have shown that 5-6 weeks is the state of embryo dormancy, which did not depend on water inflow, whereas during 6-14 weeks these embryos became capable to germinate, but this capacity was limited by water penetration through seed coat. Two distinct periods were identified in deep dormancy, namely embryo dormancy and coat-imposed dormancy (dormancy release). They differ in plasma membrane H+-ATPase behavior. During embryo dormancy, the the transformation occurred from autoinhibited form preformed during seed maturation to an active form, whereas during dormancy release the activity of enzyme increased up to the levels typical for germinating seeds.