Nitrogen fixation in seabuckthorn (Hippophae rhamnoides L.) root nodules and effect of nitrate on nitrogenase activity
Nitrogen fixation in seabuckthorn (Hippophae rhamnoides L.) root nodules and effect of nitrate on nitrogenase activity
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DOI：
10.2503/jjshs.76.185
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发表时间：
2007-07-01
影响因子：
--
通讯作者：
Kanahama, Koki
中科院分区：
文献类型：
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作者：
Kato, Kazuhisa;Kanayama, Yoshinori;Kanahama, Koki
沙棘(Hippophae rhamnodes L.)是胡颓子科的一种小果树。由于沙棘果实含有丰富的不饱和脂肪酸和维生素，这种植物具有食药两用的潜力。在这里，我们专注于共生固氮，这可能有助于该物种的培养。显微镜观察表明，沙棘根瘤具有典型的放线菌根瘤的形态特征。在无氮条件下，接种根瘤匀浆的沙棘幼苗生长正常，根瘤鲜重与植株生长呈正相关。田间条件下，5~9月气温高，光合作用活跃，根瘤固氮酶活性较高。在豆科植物的根瘤中，硝酸盐对固氮的抑制作用已经得到了很好的证明。因此，我们研究了硝酸盐对沙棘根瘤固氮酶活性的影响。沙棘根瘤固氮酶活性在短期(5天)内不受高浓度(30 MM)硝酸盐的抑制，但长期(20-30天)5 mM和10 mM的硝酸盐对其活性有明显的抑制作用。
Seabuckthorn (Hippophae rhamnoides L.) is a small fruit tree belonging to the family Elaeagnaceae. Because seabuckthorn fruit is rich in unsaturated fatty acids and vitamins, this plant has potential as a food and medicinal crop. Here, we focused on symbiotic nitrogen fixation that could aid in the cultivation of this species. Microscopic observations showed that seabuckthorn root nodules have a standard morphology characteristic of Frankiaactinorhizal root nodules. Under nitrogen-free conditions, seabuckthorn seedlings inoculated with a homogenate of root nodules grew normally, and the fresh weight of root nodules was positively correlated with plant growth. In the field, nitrogenase activity in root nodules was high from May to September, when air temperatures were high and photosynthesis was active. Inhibition of nitrogen fixation by nitrate has been well documented in the root nodules of legumes. Therefore, we investigated the effect of nitrate on nitrogenase activity in seabuckthorn root nodules. Nitrogenase activity in seabuckthorn root nodules was not inhibited by the addition of high concentrations (up to 30 mM) of nitrate over a short term (5 days), but was apparently inhibited by long-term (20-30 days) treatments with 5 and 10 mM of nitrate.