The effects of exogenous abscisic acid (ABA) on antioxidant enzymes of young and mature leaves of 4-week old Lycopersicon esculentum cv. Ailsa Craig and ABA-deficient mutant, notabilis, were investigated under drought stress. Although ABA induced increases in ascorbate peroxidase (APX), glutathione reductase (GR) and catalase (CAT) activities in drought-stressed young leaves of notabilis, CAT activities remained unchanged in both ABA-treated young and mature leaves of Ailsa Craig under drought. | Turk J Biol 29 (2005) 211-216 © TÜB‹TAK Changes in Antioxidative Enzymes of Young and Mature Leaves of Tomato Seedlings under Drought Stress Serpil ÜNYAYAR, Fazilet Özlem ÇEK‹Ç University of Mersin, Arts and Science Faculty, Department of Biology, Çiftlikköy Campus, 33343 Mersin - TURKEY Received: Abstract: The effects of exogenous abscisic acid (ABA) on antioxidant enzymes of young and mature leaves of 4-week old Lycopersicon esculentum cv. Ailsa Craig and ABA-deficient mutant, notabilis, were investigated under drought stress. Although ABA induced increases in ascorbate peroxidase (APX), glutathione reductase (GR) and catalase (CAT) activities in drought-stressed young leaves of notabilis, CAT activities remained unchanged in both ABA-treated young and mature leaves of Ailsa Craig under drought. Superoxide dismutase (SOD) activity did not substantially increase in notabilis or Ailsa Craig in all treatments. APX activity significantly increased in ABA-, drought- and drought+ABA- treated young leaves of notabilis. These results indicated that the antioxidant enzyme activities in drought-stressed and ABA-treated leaves might change with the production of active oxygen species (AOS) depending on the ABA content, and the developmental stages of leaves might contribute to the differential prevention of oxidative damage in plants exposed to drought. Key Words: Abscisic acid, Antioxidant enzymes, Drought stress, notabilis mutant, Lycopersicon esculentum Kurakl›k Stresi Alt›ndaki Domates Fidelerinin Genç ve Olgun Yapraklar›n›n Antioksidant Enzimlerindeki De¤ifliklikler Özet: Kurakl›k stresine maruz b›rak›lan 4 haftal›k Lycopersicon esculentum Mill. cv. Ailsa Craig (AC) and absisik asit (ABA) mutant› notabilis’in genç ve olgun yapraklar›nda antioksidant enzimler üzerine ABA uygulamas›n›n etkisi incelendi. ABA kurakl›k stresi uygulanan notabilis’in genç yapraklar›nda askorbat peroksidaz (AP), glutatyon reduktaz (GR) ve katalaz (KAT) .
