Changes in activities of antioxidant enzymes in radish (Raphanus sativus) seedlings in response to allelopathic effect of safflower (Carthamus tinctorius)

Abstract ROS (Reactive Oxygen Species) production is a usual plant reaction to environmental stresses such as allelopathy. Plants possess antioxidant enzymes to scavenge cells and resist against the ROS. This study was conducted to evaluate changes in antioxidant enzymes (CAT, GPX, APX) in radish seedlings in response to allelopathic effect of safflower root and shoot residues grown under normal irrigation and drought stress. Safflower allelopathic effect led to an increase in antioxidant enzymes activities. GPX activity increased more than CAT and APX. Radish seedlings exposed to safflower residue grown under drought stress showed more antioxidant enzymes activities. Root residues enhanced the activities of antioxidant enzymes greater than shoot. Seedlings exposed to root residues grown under drought stress had the highest level of antioxidant enzymes activities.

活性氧（Reactive Oxygen Species, ROS）的产生是植物应对化感作用等环境胁迫的典型生理响应。植物体内具备抗氧化酶系统，可清除细胞内活性氧并抵御ROS胁迫。本研究旨在评估正常灌溉与干旱胁迫条件下，分别在该两种环境下培育的红花根、茎残体所介导的化感作用，对萝卜幼苗体内抗氧化酶（CAT、GPX、APX）活性的影响变化。研究结果显示，红花的化感作用可显著提升抗氧化酶的活性，其中GPX活性的上调幅度高于CAT与APX。经干旱胁迫下培育的红花残体处理的萝卜幼苗，其抗氧化酶活性整体更高。红花根残体对抗氧化酶活性的诱导效果优于茎残体。其中，经干旱胁迫下培育的红花根残体处理的萝卜幼苗，其抗氧化酶活性达到最高水平。