Expression of a stress-induced hemoglobin affects NO levels produced by alfalfa root cultures under hypoxic stress
Expression of a stress-induced hemoglobin affects NO levels produced by alfalfa root cultures under hypoxic stress
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DOI：
10.1046/j.1365-313x.2003.01846.x
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发表时间：
2003-09-01
期刊：
影响因子：
7.2
通讯作者：
Hill, RD
中科院分区：
文献类型：
--
作者：
Dordas, C;Hasinoff, BB;Hill, RD
在不同的大气氧水平下，研究了表达大麦正反义血红蛋白转录物的转基因苜蓿根培养物。过表达血红蛋白基因（Hb(+)）的根培养物在3%氧气下保持根生长，而对照培养物或低表达血红蛋白（Hb(-)）的培养物在相同条件下生长下降30-70%。Hb（+）系的ATP水平和ATP/ADP比值在40和3%氧条件下无显著差异，而对照组和Hb（-）系的ATP水平和ATP/ADP比值在3%氧条件下显著降低。与有氧条件相比，在缺氧条件下生长的根培养物中，一氧化氮（NO）的产量大幅增加。Hb（-）细胞系中NO的积累量是Hb（+）细胞系的2.5倍。在含NO的40%氧条件下处理转基因根系，Hb（-）系和对照系的ATP水平和ATP/ADP比值显著下降，Hb（+）系的变化不显著。在缺氧条件下，Hb（-）细胞系的根细胞结构显示出细胞破坏的迹象，而Hb（+）细胞系在类似的生长条件下没有细胞破坏的迹象。这些结果使我们假设NO参与植物对缺氧的反应，并且血红蛋白调节缺氧细胞中NO的水平。
Transgenic alfalfa root cultures expressing sense and antisense barley hemoglobin transcripts were examined under varying levels of atmospheric oxygen. Root cultures overexpressing the hemoglobin gene (Hb(+)) maintained root growth when placed under 3% oxygen, whereas control cultures or cultures underexpressing hemoglobin (Hb(-)) experienced 30-70% declines in growth under the same conditions. ATP levels and ATP/ADP ratios for Hb(+) lines did not significantly differ in 40 and 3% oxygen, whereas the ATP levels and ATP/ADP ratios in control and Hb(-) lines were significantly lower under 3% oxygen. Large increases in the production of nitric oxide (NO) were measured in root cultures grown under hypoxic conditions compared to aerobic conditions. The amount of NO accumulated in an Hb(-) line was 2.5-fold higher than that in the Hb(+) line. Treatment of transgenic root lines under 40% oxygen with NO resulted in significant declines in the ATP levels and ATP/ADP ratio of an Hb(-) line and the control line, with no significant change in an Hb(+) line. The root cell structure of an Hb(-) line showed evidence of cell breakdown under hypoxic growth, whereas an Hb(+) line had no evidence of cell breakdown under similar growth conditions. These results lead us to hypothesize that NO is involved in the response of plants to hypoxia and that hemoglobin modulates the levels of NO in the hypoxic cell.