Carroll E W, Schwarz O J, Hickok L G
Department of Botany, University of Tennessee, Knoxville, Tennessee 37996-0011.
Plant Physiol. 1988 Jul;87(3):651-4. doi: 10.1104/pp.87.3.651.
Enzymes and metabolites associated with mitigation of paraquat toxicity were compared in two paraquat-tolerant mutants and a sensitive wild-type strain of the fern Ceratopteris richardii Brongn. In 21-day-old gametophytes, the specific activities of superoxide dismutase, catalase, peroxidase, glutathione reductase, dehydroascorbate reductase, and ascorbate peroxidase showed no differences that would explain mutant tolerance. Constitutive levels of ascorbate and glutathione also did not differ significantly in the three strains. An experiment testing the inducibility of paraquat tolerance revealed no change in the dose response of mutant or wild type gametophytes after exposure to sublethal concentrations of the herbicide. Uptake of paraquat by whole gametophytes was also equivalent in mutants and wild type. These data suggest that the physiological basis for tolerance in these mutants, unlike several other tolerant biotypes reported, does not lie in the oxygen radical scavenging system, in an inducible stress response, or in a block to whole-plant uptake.
在两种耐百草枯的突变体和一种敏感的野生型蕨类植物皱叶槐叶萍（Ceratopteris richardii Brongn.）菌株中，对与减轻百草枯毒性相关的酶和代谢产物进行了比较。在21日龄的配子体中，超氧化物歧化酶、过氧化氢酶、过氧化物酶、谷胱甘肽还原酶、脱氢抗坏血酸还原酶和抗坏血酸过氧化物酶的比活性没有差异，无法解释突变体的耐受性。三种菌株中抗坏血酸和谷胱甘肽的组成水平也没有显著差异。一项测试百草枯耐受性诱导性的实验表明，在暴露于亚致死浓度的除草剂后，突变体或野生型配子体的剂量反应没有变化。突变体和野生型中全配子体对百草枯的吸收也相当。这些数据表明，与其他几种报道的耐受生物型不同，这些突变体耐受的生理基础不在于氧自由基清除系统、诱导性应激反应或对全株吸收的阻碍。
