Dat JF, Foyer CH, Scott IM
Institute of Biological Sciences, University of Wales, Aberystwyth, Ceredigion SY23 3DA, United Kingdom (J.F.D., I.M.S.).
Plant Physiol. 1998 Dec;118(4):1455-61. doi: 10.1104/pp.118.4.1455.
Heat-acclimation or salicylic acid (SA) treatments were previously shown to induce thermotolerance in mustard (Sinapis alba L.) seedlings from 1.5 to 4 h after treatment. In the present study we investigated changes in endogenous SA and antioxidants in relation to induced thermotolerance. Thirty minutes into a 1-h heat-acclimation treatment glucosylated SA had increased 5.5-fold and then declined during the next 6 h. Increases in free SA were smaller (2-fold) but significant. Changes in antioxidants showed the following similarities after either heat-acclimation or SA treatment. The reduced-to-oxidized ascorbate ratio was 5-fold lower than the controls 1 h after treatment but recovered by 2 h. The glutathione pool became slightly more oxidized from 2 h after treatment. Glutathione reductase activity was more than 50% higher during the first 2 h. Activities of dehydroascorbate reductase and monodehydroascorbate reductase decreased by at least 25% during the first 2 h but were 20% to 60% higher than the control levels after 3 to 6 h. One hour after heat acclimation ascorbate peroxidase activity was increased by 30%. Young leaves appeared to be better protected by antioxidant enzymes following heat acclimation than the cotyledons or stem. Changes in endogenous SA and antioxidants may be involved in heat acclimation.
先前的研究表明，热驯化或水杨酸（SA）处理能够在处理后1.5至4小时内诱导芥菜（白芥）幼苗产生耐热性。在本研究中，我们调查了内源性SA和抗氧化剂的变化与诱导耐热性之间的关系。在1小时热驯化处理的30分钟时，糖基化SA增加了5.5倍，然后在接下来的6小时内下降。游离SA的增加幅度较小（2倍）但很显著。热驯化或SA处理后，抗氧化剂的变化呈现出以下相似之处。处理1小时后，还原型与氧化型抗坏血酸的比率比对照低5倍，但在2小时时恢复。从处理后2小时起，谷胱甘肽池的氧化程度略有增加。在前2小时内，谷胱甘肽还原酶活性高出50%以上。在前2小时内，脱氢抗坏血酸还原酶和单脱氢抗坏血酸还原酶的活性至少下降了25%，但在3至6小时后比对照水平高出20%至60%。热驯化1小时后，抗坏血酸过氧化物酶活性增加了30%。热驯化后，幼叶似乎比子叶或茎受到抗氧化酶的保护更好。内源性SA和抗氧化剂的变化可能与热驯化有关。
