Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, School of Life Science, Northwest University, Xi'an, China.
Biol Trace Elem Res. 2012 Jun;147(1-3):334-40. doi: 10.1007/s12011-012-9326-8. Epub 2012 Jan 13.
In present study, the effect of lanthanum (La) on the rooting of regenerated shoots of Saussurea involucrata Kar. et Kir was analyzed. Rooting occurred from regenerated shoots inoculated on a medium supplemented with La, the plant rooting hormone indole-3-acetic acid (IAA), or both La and IAA together. The highest rooting efficiency (96%), root number/shoot (8.5), and root length (63 mm) were recorded in shoots cultured on medium containing 2.5 μM IAA combined with 100 μM La(3+). In order to elucidate the mechanism of rooting enhancement by La, we examined dynamic changes in antioxidant enzyme activities in plant tissue over time in culture. We found that the activities of peroxidase (POX) and superoxide dismutase (SOD) were significantly higher in plant tissue cultured in IAA plus La than in La or IAA alone. At the same time, the highest H(2)O(2) content was detected in plant tissue in the presence of 2.5 μM IAA plus 100 μM La(3+). In light of these data and previous results, we speculate that La enhanced IAA-induced rooting by acting as a mild abiotic stress to stimulate POX and SOD activities in plant cells. Then, IAA reacted with oxygen and POX to form the ternary complex enzyme-IAA-O(2) that dissociated into IAA radicals and O(2)(-). Subsequently, IAA-induced O(2)(-) readily converted to hydroxyl radical (HO·) via SOD-catalyzed dismutation. Finally, cell wall loosening and cell elongation occurred as a consequence of HO-dependent scission of wall components, leading to root growth. The treatment of IAA combined with La resulted in the highest plantlet survival (80%) compared to single treatments with IAA or La alone. These data suggest that rare earth elements enhance root morphogenesis and the growth of S. involucrata.
在本研究中，分析了镧（La）对雪莲再生芽生根的影响。再生芽接种在添加 La、植物生根激素吲哚-3-乙酸（IAA）或 La 和 IAA 一起的培养基上，发生生根。在含有 2.5 μM IAA 与 100 μM La(3+)的培养基中培养的芽具有最高的生根效率（96%）、根/芽（8.5）和根长（63mm）。为了阐明 La 增强生根的机制，我们研究了培养过程中植物组织中抗氧化酶活性随时间的动态变化。我们发现，在含 IAA 和 La 的植物组织中，过氧化物酶（POX）和超氧化物歧化酶（SOD）的活性明显高于单独使用 La 或 IAA 的植物组织。同时，在存在 2.5 μM IAA 和 100 μM La(3+)的植物组织中检测到最高的 H2O2 含量。根据这些数据和以前的结果，我们推测 La 通过作为一种温和的非生物胁迫来刺激植物细胞中的 POX 和 SOD 活性，从而增强 IAA 诱导的生根。然后，IAA 与氧和 POX 反应形成三元复合物酶-IAA-O2，该复合物分解为 IAA 自由基和 O2(-)。随后，通过 SOD 催化的歧化作用，IAA 诱导的 O2(-)容易转化为羟基自由基（HO·）。最后，细胞壁成分的 HO 依赖性断裂导致细胞壁松弛和细胞伸长，从而导致根生长。与单独使用 IAA 或 La 相比，IAA 与 La 联合处理导致最高的植株存活率（80%）。这些数据表明，稀土元素增强了雪莲的根形态发生和生长。
