以2种不同低钾耐性大果番茄(钾敏感型番茄081018和耐低钾型番茄081034)为材料,比较低钾处理下2种番茄叶片中活性氧产生及抗氧化酶系活性和相关基因表达差异,明确植物叶片对低钾胁迫的响应机制.结果显示:(1)钾敏感型番茄在低钾胁迫时,叶片中各种保护酶(SOD及其同工酶、POD、CAT、APX)活性随处理时间延长呈下降趋势,同时活性氧(O2-、H2O2)和MDA含量急剧增加;耐低钾型番茄在低钾胁迫条件下,其各类保护酶活性均比对照水平有所升高,而且O2-、H2O2和MDA的含量增加也较少.(2)钾敏感型番茄在低钾胁迫时叶片内Cu/Zn-SOD、CAT和APX基因的相对表达量均有下降趋势,而同期耐低钾型番茄在低钾胁迫时Cu/Zn-SOD、CAT和APX的表达却明显增加,这与其对应的酶活性变化趋势同步.研究表明,低钾胁迫使耐低钾型番茄具有较高保护酶基因表达量,产生较高的保护酶活性,可降低活性氧的破坏作用,防止膜渗透性增加,使之对低钾的适应性较强,而钾敏感番茄品系则相反.%The aim of this work was to study the relationship between low potassium stress and the reactive oxygen species system. The tomato plants were grown in hydroponic systems to determine the role of reactive oxygen species (ROS) in the leaves response to low potassium stress. Parameters of oxidative stress superoxide (O2- ) ,malondialdehyde (MDA) and hydrogen peroxide (H2O2) concentration and activities of antioxidant enzymes, such as superoxide dismutase (SOD) , catalase (CAT) , ascorbate peroxidase (APX) were investigated. The results indicated that:(l)The protective enzyme activities in the potassium-sensitive tomato were significantly depressed in the low potassium treatment compared to controls. While reactive oxygen species and MDA content showed significant differences between control and low potassium treatment. (2)The protective enzyme activities were increased in potassium-tolerant tomato compared with the control,and its reactive oxygen species and MDA content were increased. Relative expression levels of Cu/ Zn-SOD ,CAT and APX were analyzed in two kinds of tomato genotypes. The results showed that potassium-tolerant tomato had high protective enzyme expression under the low potassium stress,while potassium sensitive tomato was the opposite. These results show that higher protection enzyme activities probably scavenge H2O2 and O2- , resulting in preventing the membrane permeability, and this can increase the adaptability to low potassium.
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