Song Song-Quan, Tian Mei-Hua, Kan Jing, Cheng Hong-Yan
Institute of Botany, the Chinese Academy of Sciences, Beijing 100093, China.
J Integr Plant Biol. 2009 Jul;51(7):646-53. doi: 10.1111/j.1744-7909.2009.00836.x.
Long-term preservation of recalcitrant seeds is very difficult because the physiological basis on their desiccation sensitivity is poorly understood. Survival of Antiaris toxicaria axes rapidly decreased and that of immature maize embryos very slowly decreased with dehydration. To understand their different responses to dehydration, we examined the changes in mitochondria activity during dehydration. Although activities of cytochrome (Cyt) c oxidase and malate dehydrogenase of the A. toxicaria axis and maize embryo mitochondria decreased with dehydration, the parameters of maize embryo mitochondria were much higher than those of A. toxicaria, showing that the damage was more severe for the A. toxicaria axis mitochondria than for those of maize embryo. The state I and III respiration of the A. toxicaria axis mitochondria were higher than those of maize embryo, the former rapidly decreased, and the latter slowly decreased with dehydration. The proportion of Cyt c pathway to state III respiration for the A. toxicaria axis mitochondria was low and rapidly decreased with dehydration, and the proportion of alternative oxidase pathway was high and slightly increased with dehydration. In contrast, the proportion of Cyt c pathway for maize embryo mitochondria was high, and that of alternative oxidase pathway was low. Both pathways decreased slowly with dehydration.
顽拗性种子的长期保存非常困难，因为人们对其脱水敏感性的生理基础了解甚少。随着脱水，见血封喉轴的存活率迅速下降，而未成熟玉米胚的存活率下降非常缓慢。为了解它们对脱水的不同反应，我们研究了脱水过程中线粒体活性的变化。虽然随着脱水，见血封喉轴和玉米胚线粒体的细胞色素（Cyt）c氧化酶和苹果酸脱氢酶活性均下降，但玉米胚线粒体的参数远高于见血封喉轴，这表明见血封喉轴线粒体的损伤比玉米胚线粒体更严重。见血封喉轴线粒体的状态I和状态III呼吸高于玉米胚，随着脱水前者迅速下降，后者缓慢下降。见血封喉轴线粒体的Cyt c途径占状态III呼吸的比例较低，且随着脱水迅速下降，交替氧化酶途径的比例较高，且随着脱水略有增加。相比之下，玉米胚线粒体的Cyt c途径比例较高，交替氧化酶途径比例较低。两种途径随着脱水均缓慢下降。
