Antioxidant Potential and Expression of Lea Genes under Heat Stress in Two Wheat Cultivars Differing in Heat Tolerance

摘要

Two wheat (Triticum aestivum L.) cultivars differing in heat tolerance, 'C306' (heat tolerant) and 'PBW343' (heat susceptible) were compared for their growth, antioxidant response and expression of late embryogenesis abundant (LEA) genes under heat stress (37°C) given to 4-day old seedlings. Dry biomasses and water contents in shoots and roots of 'C306' were comparatively less affected under heat stress than of 'PBW343'. Root dry mass to shoot dry mass ratios were improved by higher amount in 'C306'than in 'PBW343' under stress. Decline in proteins contents of roots under heat stress was higher in 'PBW343' than 'C306'. Ascorbate contents and ascorbate to dehydroascorbate ratios were comparatively less affected in shoots and roots of 'C306' than of'PBW343' under stress. 'PBW343' roots showed higher levels of malondialdehyde (MDA) under prolonged stress. Dehydroascorbate and proline contents did not increase during heat stress in shoots and roots of both cultivars. Activities of antioxidant enzymes were maintained in shoots of 'C306' but affected in shoots of 'PBW343' during the stress period. In roots of both cultivars, levels of antioxidant enzymes were decreased under heat stress. Glutathione-S-transferase-F (GST-F, member of phi class) was induced only in C306, GST-^i (member of tau class) was not induced in both cultivars, glutathione-peroxidase (GPX) was induced by same amount in both cultivars, peroxisomal-ascorbate peroxidase was induced only in PBW343 under heat stress. Some of LEA group 2 and group 4 genes were induced while of group 3 genes were not induced under heat stress. Among group 2, Wcor410c was induced mainly in C306, Tdl6 was induced mainly in PBW343, Td27e was induced higher in 'C306', Wdhnl3 was not induced in both cultivars under heat stress. LEA group4 Td29 was induced higher in 'C306' than in 'PBW343' under heat stress.