水分胁迫下苹果幼苗叶绿体活性氧代谢对光合作用的影响

The Effects of Active Oxygen Metabolism on Photosynthesis of Young Apple Trees under Water Stress

以2年生八棱海棠盆栽幼树为试材,研究了水分胁迫下叶绿体活性氧代谢对光合作用的影响。结果表明,在胁迫初期,叶绿体中超氧阴离子自由基产生速率和H2O2含量变化不明显,随着胁迫时间延长,超氧阴离子自由基和H2O2含量迅速增加;同时,活性氧清除酶系统SOD、ASP活性显著提高,叶绿体仍维持较高的光合活性,Hill反应和FBPase活性变化不明显,CO2供应不足可能是此时叶片Pn下降的主要原因。重度胁迫下,SOD、ASP活性降低,超氧阴离子自由基和H2O2累积,Hill反应和FBPase活性降低,叶绿体光合活性下降,正常的结构和功能被破坏,活性氧代谢失调而诱发的非气孔因素成为此时净光合速率下降的主要原因。

2-years-old seedlings of Malus.micromalus Makino. were used for studying the effects of active oxygen metabolism under the soil stress on photosynthetic rate. With the duration of water stress, the H_2O_2 content and production increased; the SOD and ASP active increased. The protective enzyme SOD and ASP can inhibit the accumulation of active oxygen and lessen membrane damage; the chloroplast still maintain the higher photo activity, Hill reaction and FBPase activity didn't obviously changed, the decline of the photosynthetic rate was due to the CO_2 concentration decreased in the cell under mild and moderate water stress. Along with the duration of water stress, the active of SOD and ASP were decreased, the excessive accumulation of and H_2O_2 was due to the reduce of the protective enzyme SOD and ASP. The excessive accumulation induced membrane damage, photo activity decreased in chloroplast, Hill reaction and FBPase activity obviously decreased. The results indicated: the decline of photosynthetic rate was due to disorder of active oxygen metabolism under severe water stress.