水分胁迫下苹果叶片的H_2O_2代谢

H_2O_2 Metabolism of Apple Leaves Under Water Stress

轻度水分胁迫下苹果叶片Pr迅速升高 ,CAT活性变化不大 ,NaHSO3 处理能显著降低叶内H2 O2 含量 ,表明光呼吸的加强促进了H2 O2 产生可能是叶内H2 O2大量积累的主要原因 ;中度水分胁迫下叶片AsA含量的下降和Mehler反应的增强都非常明显 ,DDTC和AsA处理都能有效降低叶内H2 O2 积累 ,但MV处理的作用不大 ,说明叶片H2 O2 主要来源于Mehler反应 ,AsA降解造成叶片对H2 O2 清除能力的下降是其积累的根本原因 ;严重水分胁迫时 ,NaHSO3 和DDTC都不能有效地减轻叶内H2 O2 积累 ,光呼吸和Mehler反应都可能不是H2 O2

Under slight water stress, rate of photorespiration rapidly rose but CAT activity faintly changed in apple leaves(Figs.2,4), H 2 O 2 content could be decreased obviously when leaves treated with NaHSO 3 (Fig.3). This indicated H 2 O 2 production enhancement through photorespiration accelerating possibly was the main reason why H 2 O 2 accumulated in leaves. While at the moderate water stress stage, both AsA content reduction and Mehler reaction increase happened strongly(Figs.4,2). DDTC and AsA treatment could depress H 2 O 2 accumulation effectively(Figs.3,5), but MV had a little affect(Fig.5). Which illuminated that Mehler reaction was the main source of H 2 O 2 production and it accumulated mainly because the ability of H 2 O 2 elimination decreased due to AsA decomposition. Under severe water stress, neither NaHSO 3 nor DDTC did depress H 2 O 2 content and this showed both photorespiration and Mehler reaction were not the main source of H 2 O 2 production in apple leaves probably(Fig.3).