乾、溼逆境對甘藷葉片蛋白質、過氧化酶及一些塊根性狀影響之研究

Effects of Drought and Flooding Stresses on Leaf Protein, Peroxidase and Storage Root's Characters of Sweet Potato (Ipomoea batatas (L.) Lam.)

過氧化酶一般認為其與木質素的生合成、IAA的氧化、有機過氧化物的去毒作用、根和枝節的分生、葉的形成、老化及節間的伸長有密切關聯。本試驗利用七個甘藷品種在生長中後期進行乾濕逆境處理，每隔25日調查葉片蛋白質、過氧化酶之活性及同功異構酶帶型，及其與塊根性狀間之相關。過氧化酶圖譜分析發現在陽向條帶有15條以上，七個品種間的差異集中在a13-a15這一條帶區，陰向條帶雖大多集成一長條，但仍可分出c1、c2及c3三型，品種間變異則以濃淡為主。進行乾濕處理時，a7-a12條帶變的很淡，有若干品種幾近於無，而a14變得較濃，a13及a15較淡，陰向條帶則普遍有擴散模糊的現象。利用SAS統計分析發現乾旱處理使葉片蛋白質含量下降、過氧化酶活性增加，淹水處理也有相似的效應，但不若乾旱處理明顯，而在中期乾濕處理、生長後期回復正常供水時，它們有恢復正常生長的趨勢，但中期乾旱處理的恢復能力較中期淹水為差。在地上部、纖維根及塊根鮮重上，後期乾旱處理表現最差，塊根乾物量受乾濕處理、糖含量受淹水處理、澱粉含量受乾旱處理之影響而降低，而葉片過氧化酶各區酶譜帶型亦分別與地上部、纖維根及塊根鮮重、塊根乾物量、蛋白質及澱粉含量有顯著相關。

Peroxidase is believed to play an important role in lignin synthesis, IAA oxidation, detoxification of H2~ and is also known to have close relationship with shoot and root initiation, leaf formation, senescence, internode elongation, and pathogenic infection, etc. In this experiment, five treatments, including control, middle or late stage flooding, and middle or late stage drought were conducted on seven sweet potato cultivars. The effects of flooding and drought stresses on leaf protein content, peroxidase zymograms and activity as well as the relationship between zymograms and horticultural traits were investigated every thenty-five days. Zymogram variations in leaf peroxidase were noted among the seven cultivars. At least 15 anodal bands and 3 cathodal bands were observed. Cultivar differences were most pronounced at the zone (a13-a15 bands). Variation in band intensity was also observed at cathodal bands. Drought and flooding treatments had the influence on band intensity, especially in a12～a7 bands. Statistical analysis indicated that treatments and genetic background had significant effects on peroxidase activity and protein content. In general, drought treatment tended to decrease protein contents while increase peroxidase activity. Hooding had similar effects but was not as distinct as drought treatment. When flooding only in the middle stage of growth period, plants had the ability to recover growth. However, the performance of recovery in drought treatment at the same period was much worse than that of flooding. Investigations into horticultural traits revealed drought treatment in the late stage of growth period had significant negative effects on fresh weights of top portions, fibrous roots and storage roots. On the storage root, dry matter content was lowered by both treatment, sugar content was lowered by flooding and starch lowered by drought treatment. Leaf peroxidase zymogram was also closely vela ted to the contents of fresh weights of top portions, fibrous roots, and storage roots, dry matter, protein and starch in storage root.