Please use this identifier to cite or link to this item:
Responses of Peroxidation and Antioxidative Systems in Corn(Zea mays L.) Seedling During Waterlogging Stress
|關鍵字:||Corn;玉米;Waterlogging Stress;Peroxidation;Antioxidative Systems;Plant Growth Regulators;Polyamines;Active Oxygen Species Scavengers;浸水逆境;過氧化作用;抗氧化系統;植物生長調節素;多元胺;活性氧族清除劑||出版社:||農藝學系||摘要:||
台南19號玉米幼苗進行十天的浸水處理，結果顯示植株生長受阻，乾物重減少，同時葉片葉綠素和蛋白質含量皆降低。分析植株過氧化作用，顯示隨著浸水日數的延長，植株體內超氧自由基產生速率和過氧化氫含量亦呈現增加，同時植株遭受過氧化傷害（即MDA含量增加）的程度亦愈加劇。進一步測定抗氧化系統的反應，結果顯示酵素性抗氧化物，除了根部glutathione reductase（GR）活性表現增加外，隨著浸水日數延長，葉片superoxide dismutase（SOD） 、ascorbate peroxidase（AP） 和GR活性，以及根部SOD和AP活性皆減少。至於非酵素性抗氧化物的表現，台南19號幼苗於浸水期間，葉片和根部ascorbate含量皆呈現增加趨勢；植株glutathione含量以還原態（reduced form glutathione, GSH）為主，葉片GSH含量在浸水初期明顯增加，而根部GSH含量則是在浸水後期表現增加。顯然地，浸水處理導致玉米植株抗氧化系統防禦能力的改變，這種改變可能涉及到植株的過氧化傷害。
The purpose of this study is to explore the responses of peroxidation and antioxidative systems of corn seedling under the waterlogging stress. In order to select the proper cultivar as the experimental material, pot-grown V3 seedlings of four corn cultivars (Tainung 1, Tainung 351, Tainan 17, and Tainan 19) were subjected to waterlogging treatment. It showed that Tainan 19 was the most susceptible to waterlogging and thus used as experimental material for further studies.
During 10 days waterlogging period, corn seedling of Tainan 19 showed a decrease in growth, dry weight, the content of chlorophyll and soluble protein. Waterlogging treatment resulted in increase of superoxide anion generation, H2O2 production, and MDA content in corn plants. The enzymatic antioxidants (SOD, AP and GR) of both leaves and roots of waterlogging seedling were reduced except GR activity in root. In nonenzymatic antioxidants, waterlogging increased the content of ascorbate of corn seedling. The reduced form of glutathione (GSH), an increase was also found in both leaves and root of waterlogging seedling, however, the time of increase in the leaves was earlier than that in roots.
Responses of peroxidation and antioxidative systems in corn seedlings of Tainan 19 on waterlogging treatment were increased by age of leaves. Although the antioxidative systems in the older leaves were enhanced earlier than that of the younger, the reduction of defense systems in the older leaves were faster than that of the younger. Peroxidative injury in adventitious root was much greater than that in seminal root under waterlogging treatment. Ascorbate and glutathione contents in both seminal and adventitious roots showed similarity at the early stage of the experiment, but glutathione content of seminal root was significantly reduced than that of adventitious root. The activities of AP and GR in adventitious root were higher than that of seminal root during this experiment, but SOD activity was not different in both roots. Apparently, these results indicated that waterlogging induced damage of peroxidation and antioxidative systems, depend on different tissue and plant age of corn seedling.
Draining is one of the most effective way to alleviate injury and recover growth from waterlogging. In the drainage experiment, corn seedling of Tainan 19 was recovered, especially in root. Peroxidation was also significantly decreased in drained corn seedling and there was not appearance of post-flooding injury. Decrease in peroxidation of drained plant was assumed due to increased in antioxidative defense capacities by enhanced activities of AP and GR.
In addition to draining, application of plant growth regulators, polyamines and active oxygen species scavengers were expected to eliminate waterlogged damage of corn seedling and enhanced antioxidative defense capacities. The results indicated pretreatment with various chemical agents was more effective than that of treatments with waterlogging simultaneously. Among plant growth regulators, the effect of BA treatment was the greatest and significantly reduced injury and peroxidation of waterlogged corn plants. ABA treatment enhanced serious injury and peroxidation. However, antioxidative defense mechanisms were promoted in both application of BA and ABA, especially increase of glutathione content. It was suggested that increasing glutathione content in plant by ABA applied could not scavenged the production of excessive active oxygen species, and lead to increased damage of peroxidation. In the exogenous polyamines treatments, there was no direct evidence for the relationship between recovery effects and antioxidative systems, although the waterlogging injury of corn seedling were slightly reduced.
In the exogenous active oxygen species scavengers treatment, the effects of AsA and GSH on recovery of plant growth and dry weight accumulation were greater than others. The recovery mechanism of the two agents might not due to reduction of plant peroxidation.
Under post-waterlogging, treatment of BA, ABA, Put, AsA and GSH sprayed simultaneously to Tainan 19 corn seedling. These exogenous agents were not shown an additional effect on the recovery plant by draining. Application of ABA on the drained plant was even increased in peroxidative injury, which resulted from the reduction of antioxidative capacities that may be due to the declined glutathione content. Therefore, no significant effects were observed for applied agents in recovery of drained corn plant.
In summary, waterlogging stress causes an accumulation of active oxygen species and lead to an increased lipid peroxidation in the corn plant of Tainan 19. Waterlogging stress also resulted in the reduced activities of enzymatic antioxidants－SOD, AP and GR and altered contents of nonenzymatic antioxidants－ascorbate and glutathione, that lead to reduce capacities of the antioxidative systems and accelerate the peroxidative injury of corn plant.
Many methods were used to overcome or alleviate the waterlogged damage in this thesis. Among them, treatment of direct drainage was found the most economical and effective way. Exogenous treatment with BA, AsA and GSH before waterlogging stress were also effective in alleviating waterlogged damage of corn plant in some extents. And this effect was related to antioxidative systems, especially for glutathione content alteration in the ascorbate-glutathione cycle, which may play an important role in defense and detoxicity. However, the alleviative effects of damage by application of plant growth regulators or active oxygen species scavengers with waterlogging treatment simultaneously was lower than that of pretreatment in Tainan 19 corn seedling. No additional effects were observed in chemical agents application on corn plant with simutaneous draining treatment.
|Appears in Collections:||農藝學系|
Show full item record
TAIR Related Article
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.