Kato-Noguchi Hisashi
Faculty of Agriculture, Department of Biochemistry and Food Science, Kagawa University, Miki, Kagawa, Japan.
J Plant Physiol. 2004 Jul;161(7):803-8. doi: 10.1016/j.jplph.2003.11.004.
Although most cereal roots cannot elongate under anoxic conditions, primary roots of three-day-old rice (Oryza sativa L.) seedlings were able to elongate during a 24-h period of anoxia. Hypoxic pretreatment (H-PT) increased the elongation of their roots. Sucrose synthase (EC 2.4.1.13), glucokinase (EC 2.7.1.2), fructokinase (EC 2.7.1.4), pyruvate decarboxylase (EC 4.1.1.1) and alcohol dehydrogenase (EC 1.1.1.1) activities were increased by anoxia in both H-PT and non-pretreated (N-PT) roots. However, these activities were greater in the H-PT roots than in the N-PT roots. The average rate of production of ethanol for the initial 6h after the onset of anoxia was 3.7 and 1.4 micromolg(-1) fresh weight h(-1) for the H-PT and N-PT roots, respectively, suggesting that ethanolic fermentation may increase more quickly in the H-PT roots than in the N-PT roots. Roots of the seedlings lost ATP and total adenine nucleotides in anoxia, however, the H-PT roots maintained higher levels of ATP and total adenine nucleotides compared to the N-PT roots. These results show that rice roots are able to utilize the set of enzymes involved in the metabolism of soluble sugars under anoxia. The ability to maintain an active fermentative metabolism for production of ATP by fueling the glycolytic pathway with fermentable carbohydrate is probably greater in H-PT than in N-PT roots.
虽然大多数谷类作物的根在缺氧条件下无法伸长，但三天大的水稻（Oryza sativa L.）幼苗的初生根在24小时缺氧期间能够伸长。缺氧预处理（H-PT）增加了它们根的伸长。缺氧使H-PT根和未预处理（N-PT）根中的蔗糖合酶（EC 2.4.1.13）、葡萄糖激酶（EC 2.7.1.2）、果糖激酶（EC 2.7.1.4）、丙酮酸脱羧酶（EC 4.1.1.1）和乙醇脱氢酶（EC 1.1.1.1）活性均增加。然而，这些活性在H-PT根中比在N-PT根中更高。缺氧开始后的最初6小时内，H-PT根和N-PT根中乙醇的平均产生速率分别为3.7和1.4微摩尔克鲜重小时，这表明H-PT根中乙醇发酵可能比N-PT根中增加得更快。幼苗的根在缺氧时会失去ATP和总腺嘌呤核苷酸，然而，与N-PT根相比，H-PT根维持了更高水平的ATP和总腺嘌呤核苷酸。这些结果表明，水稻根能够在缺氧条件下利用参与可溶性糖代谢的一组酶。通过用可发酵碳水化合物为糖酵解途径供能来维持活跃的发酵代谢以产生ATP的能力，H-PT根可能比N-PT根更强。
