低温順化したCattleyaとCymbidium葉の過酸化水素含量および抗酸化酵素活性の低温処理による変動(発育抑制)  [in Japanese] Changes in Concentration of Hydrogen Peroxide and Activities of Antioxidative Enzymes in Chilled Leaves of Acclimated Cattleya and Cymbidium Plants (Growth Regulation)  [in Japanese]

Sophrolaeliocattleya Estella Jewel (Cattleya)とCymbidium Sazanami (Cymbidium)を10月10日から室外で2か月間栽培した株を低温順化株とし,13〜28℃のハウスで管理した株を未順化株とした.低温順化株と未順化株に対して低温処理(5℃,暗黒条件,24時間)を行った.低温処理中および処理後の昼間では,両植物種とも低温順化株の葉の過酸化水素含量は未順化株より低かった.Cattleyaのスーパーオキシドジスムターゼ(SOD)活性は低温順化株において低温処理中,未順化株よりやや高く推移した.アスコルビン酸ペルキシダーゼ(APX)活性は低温処理中およびその後とも未順化株より高く推移し,カタラーゼ(CAT)活性は低温順化株において低温処理中は漸次上昇したが,未順化株では大きく変動した.CymbidiumのSODとAPX活性は低温処理中,低温順化株で高い値を示し,CAT活性は低温処理中,低温順化株では未順化株のような一時的低下がみられず,低温処理後も未順化株より低い値を示した.これらの結果から,秋期の低温順化は両植物種の低温耐性を抗酸化的に増強することが示唆された.

Naturally cold-acclimated (2 months from 10th Oct.) and non-acclimated (grown in a greenhouse at 13-28℃) potted plants of Sophrolaeliocattleya Estella Jewel (Cattleya) and Cymbidium Sazanami (Cymbidium) were exposed to 5℃ for 24 hrs in the dark. Lower hydrogen peroxide concentrations were shown in plant leaves of cold-acclimated plants than in those of the non-acclimated ones during chilling treatment and during the daytime after that treatment. Superoxide dismutase (SOD) activities of cold-acclimated Cattleya leaves changed slightly at higher levels than those of non-acclimated ones during chilling treatment. Ascorbate peroxidase (APX) activities of the cold-acclimated leaves shifted to higher levels compared with non-acclimated leaves during and after cold treatment. The catalase (CAT) activities increased gradually in leaves that were cold-acclimated by chilling treatment, although those activities in non-acclimated leaves fluctuated markedly by chilling. SOD and APX activities of Cymbidium showed high values in cold-acclimated plants during chilling treatment. CAT activities in the cold-acclimated plants did not decrease temporarily like non-acclimated ones during chilling treatment, and decreased after the chilling treatment. From these results, it was indicated that cold-acclimation in autumn strengthened cold-resistance of both plant species in antioxidant relations.