Impacts of ascorbic acid on germination, antioxidant enzymes and ultrastructure of embryo cells of aged Elymus sibiricus seeds with different moisture contents

Abstract

This study determined the effects of exogenous ascorbic acid (AsA) treatment on germination, membrane lipid peroxidation, activities of antioxidant enzymes and ultra-structure of embryo cells of Siberian wildrye (Elymus sibiricus l.) seeds with different moisture contents (4%, 10% and 16%) after ageing at 45°c for 48 h. germination percentage and activities of enzymes declined, electrical conductivity value of seeds increased significantly as moisture content increased from 4% to 16%. However, ascorbic acid treatment had protective effects on alleviating the damage of ageing to seeds membrane integrity and structure of mitochondria, which was in accordance with the decrease of electrical conductivity and malondialdehyde (MDA) content, especially for seeds with 10% moisture content. Ascorbic acid treatment significantly (P<0.05) inhibited the loss of seed germination at 10% moisture content, and correspondingly electrical conductivity decreased and activities of catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) improved. In addition, ultra structure observation of embryo cells showed that serious damage occurred in seeds with 16% moisture content, including the broken cellular and nuclear membrane, pyknotic nucleolus and swollen mitochondria. Although activities of CAT, APX and GR were improved by the exogenous ASA, it had no obviously protective effect on integrity of membrane system and mitochondria. Seed moisture of Siberian wildrye played a vital role in the function of ASA, which provided an efficient treatment to deal with the antioxidant effects of storage and ageing at seed moisture of 10%.