ANTIOXIDANT ENZYME RESPONSES OF PERENNIAL RYEGRASS ACCESSIONS DURING COLD ACCLIMATION

摘要

Cold acclimation responses of two perennial ryegrass (Lolium perenne L.) accessions were investigated to determine the role of proline-associated pentose phosphate pathway (PPP) for phenolic biosynthesis and stimulation of antioxidant response systems.Perennial ryegrass accessions PI 223178 (PR-1) and PI 598433(PR-2) were subjected to a cold acclimation treatment that consisted of a constant 2 °C for 21 d.Leaves were harvested weekly for assessment of phenolic content,proline content,and antioxidant enzyme activities.After 21 d of cold acclimation,PR-2 exhibited higher leaf phenolic content,proline accumulation,and total antioxidant activity compared to PR-1.Higher glucose-6-phosphate dehydrogenase (G6PDH) and proline dehydrogenase (PDH) activities were also observed in PR-2,which suggested an increased role of proline-associated PPP in this accession during cold acclimation.Higher catalase (CAT) activity in PR-2 suggested a counter mechanism of this accession against low temperature-induced cellular peroxidation.This study indicated that fitness of perennial ryegrass accessions at low temperature may be due to a combination of many biochemical properties including,antioxidant stimulation,proline accumulation,and phenolic biosynthesis through stimulation of PPP to support these anabolic responses.