干旱胁迫下水曲柳苗木细根线粒体的形态及活性变化

doi:10.3773/j.issn.1005-264x.2010.12.012

摘要/Abstract

摘要：

根系依赖根细胞内线粒体呼吸代谢产生的能量, 不断从土壤中获取养分。在胁迫条件下, 线粒体的结构和功能会发生一定的变化, 从而影响根系的功能。土壤干旱是最容易引起苗木细根衰老死亡的非生物胁迫因子之一。为了更好地认识干旱胁迫下细根线粒体的结构和功能变化, 对土壤干旱胁迫下水曲柳(Fraxinus mandshurica)不同颜色细根皮层薄壁细胞内线粒体的超微结构(线粒体数量、形态)、线粒体的呼吸功能、线粒体膜脂质氧化(膜透性变化、过氧化氢含量等)情况进行了研究。结果表明: (1)干旱胁迫下, 水曲柳白色及黄色根皮层薄壁细胞内线粒体形状、结构及分布数量与对照相似, 无显著差异。干旱胁迫下产生的褐色根皮层薄壁细胞线粒体数量减少, 分布密度也变小。线粒体内、外膜先后发生不同程度的解体, 最后消失。(2)干旱胁迫显著干扰了线粒体膜的正常呼吸耦联作用, 细根线粒体呼吸控制率(RCR)与磷氧比(无机磷酸/分子氧, P/O)均显著低于对照(p < 0.05)。随着细根颜色加深, 线粒体RCR和P/O值逐渐下降, 白色根﹥黄色根﹥褐色根。褐色根线粒体RCR值最低, 接近极值1。说明褐色根线粒体结构完整性最差, 能量转化效率最低。(3)干旱胁迫下, 不同颜色细根线粒体内的H₂O₂含量、线粒体膜透性、膜脂氧化产物丙二醛(MDA)含量均显著高于对照(p < 0.05)。且随着细根颜色加深, 各个值增加明显。分析可能是由于干旱胁迫导致线粒体内H₂O₂含量升高, 线粒体膜脂质过氧化(MDA含量升高), 膜结构受到破坏(膜透性增加) (电镜下可见部分线粒体内膜电子密度下降及外膜解体)。线粒体膜结构完整性的破坏, 直接影响了线粒体呼吸代谢反应, 使线粒体呼吸功能下降。

关键词: 干旱胁迫, 细根, 水曲柳, 线粒体

Abstract:

Aims In addition to producing energy, mitochondria in fine roots play a dual role in oxidative stress, being both reactive oxygen species (ROS) producers and integrators of the cell antioxidant defense systems. Structural integrity of mitochondria is the fundamental guarantee for producing ATP in fine roots. Therefore, our objective was to observe mitochondrial structural and functional changes in Fraxinus mandshurica fine roots of different colors under drought stress to better relate different-colored fine roots with different functions and to develop a theoretical basis for judging fine root death according to root color.
Methods We observed the number, distribution and structure of mitochondria in different-colored fine roots cortical parenchyma cells of F. mandshurica by electric microscopy. Mitochondrial respiratory control ratio (RCR) and phosphorus oxygen ratio were measured by oxygen electrode. The malondialdehyde (MDA) content, membrane permeability and H₂O₂ concentration were studied by UV spectrophotometer.
Important findings Compared with the control, there were no significant differences of mitochondrial shape, structure or distribution under drought stress in white and yellow roots’ cortical parenchyma cells. However, there were fewer mitochondria in brown fine roots under drought stress, and their membranes had disintegrated and disappeared to a different degree. The normal breathing coupling of mitochondrial membrane role in fine-root mitochondria was disturbed significantly under drought stress. The value of RCR and P/O were significantly lower than that of the control (p < 0.05). With deepened fine-root color, mitochondrial RCR and P/O value decreased gradually, white roots > yellow roots > brown roots. The H₂O₂content, mitochondrial membrane permeability and MDA content in different-colored fine roots mitochondria under drought stress were significantly higher than the control (p < 0.05). Values increased markedly with deepened color.

Key words: drought stress, fine root, Fraxinus mandshurica, mitochondria

卫星, 王政权, 张国珍. 干旱胁迫下水曲柳苗木细根线粒体的形态及活性变化. 植物生态学报, 2010, 34(12): 1454-1462. DOI: 10.3773/j.issn.1005-264x.2010.12.012

WEI Xing, WANG Zheng-Quan, ZHANG Guo-Zhen. Morphological and activity variation of mitochondria in fine roots of Fraxinus mandshurica seedling under drought stress. Chinese Journal of Plant Ecology, 2010, 34(12): 1454-1462. DOI: 10.3773/j.issn.1005-264x.2010.12.012

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https://www.plant-ecology.com/CN/Y2010/V34/I12/1454

图/表 9

图1 水曲柳苗木细根皮层薄壁细胞线粒体超微结构。A, 对照白色根。B, 对照黄色根。C, 干旱胁迫下白色根。D, 干旱胁迫下黄色根。E-O, 干旱胁迫下褐色根。

Fig. 1 Mitochondrial ultrastructures in cotical parenchyma of fine roots in Fraxinus mandshurica seedlings. A, White root of control. B, Yellow root of control. C, White root under drought stress. D, Yellow root under drought stress. E-O, Brown root under drought stress.

图2 干旱胁迫对水曲柳苗木不同颜色细根线粒体数量的影响(平均值±标准误差)。不同的小写字母表示干旱胁迫与对照之间的差异显著(p < 0.05); 不同的大写字母表示干旱处理下不同颜色细根间的差异显著(p < 0.05)。

Fig. 2 Effects of drought stress on mitochondrial quantity of fine roots with different color in Fraxinus mandshurica seedlings (mean ± SE). Different small letters mean significant differences (p < 0.05) between drought treatments and control; different capital letters mean significant differences (p < 0.05) among different color fine roots.

图3 干旱胁迫对水曲柳苗木不同颜色细根线粒体呼吸态3的影响(平均值±标准误差)。注释同图2。

Fig. 3 Effects of drought stress on mitochondrial respiratory state 3 of fine roots with different color in Fraxinus mandshurica seedlings (mean ± SE). Notes see Fig. 2.

图4 干旱胁迫对水曲柳苗木不同颜色细根线粒体呼吸态4的影响(平均值±标准误差)。注释同图2。

Fig. 4 Effects of drought stress on mitochondrial respiratory state 4 of fine roots with different color in Fraxinus mandshurica seedlings (mean ± SE). Notes see Fig. 2.

图5 干旱胁迫对水曲柳苗木不同颜色细根线粒体呼吸控制率的影响(平均值±标准误差)。注释同图2。

Fig. 5 Effects of drought stress on mitochondrial respiratory control ratio (RCR) variations of fine roots with different color in Fraxinus mandshurica seedlings (mean ± SE). Notes see Fig. 2.

图6 干旱胁迫对水曲柳苗木不同颜色细根线粒体P/O值的影响(平均值±标准误差)。注释同图2。

Fig. 6 Effects of drought stress on mitochondrial P/O value of fine roots with different color in Fraxinus mandshurica seedlings (mean ± SE). Notes see Fig. 2.

图7 干旱胁迫对水曲柳苗木不同颜色细根线粒体膜吸收光度的影响(平均值±标准误差)。注释同图2。

Fig. 7 Effects of drought stress on mitochondrial membrane light absorbability of fine roots with different color in Fraxinus mandshurica seedlings (mean ± SE). Notes see Fig. 2.

图8 干旱胁迫对水曲柳苗木不同颜色细根线粒体丙二醛(MDA)含量的影响(平均值±标准误差)。注释同图2。

Fig. 8 Effects of drought stress on mitochondrial malondiadehyde (MDA) content of fine roots with different color in Fraxinus mandshurica seedlings (mean ± SE). Notes see Fig. 2.

图9 干旱胁迫对水曲柳苗木不同颜色细根线粒体H2O2含量的影响(平均值±标准误差)。注释同图2。

Fig. 9 Effects of drought stress on mitochondrial H2O2 content of fine roots with different color in Fraxinus mandshurica seedlings (mean ± SE). Notes see Fig. 2.

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