Li Wen, Qi Lin, Lin Xiaodong, Chen Huhui, Ma Zhanqi, Wu Keqiang, Huang Shangzhi
School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China.
J Integr Plant Biol. 2009 Mar;51(3):279-86. doi: 10.1111/j.1744-7909.2008.00790.x.
A manganese superoxide dismutase (Mn-SOD) gene, NnMSD1, was identified from embryonic axes of the sacred lotus (Nelumbo nucifera Gaertn.). The NnMSD1 protein contains all conserved residues of the Mn-SOD protein family, including four consensus metal binding domains and a signal peptide for mitochondrial targeting. Southern blot analysis suggests the existence of two Mn-SOD genes in sacred lotus. NnMSD1 was highly expressed in developing embryonic axes during seed development, but appeared in cotyledons only at the early stage of development and became undetectable in the cotyledons during late embryogenesis. The expression of the NnMSD1 gene in germinating embryonic axes, in response to various stresses such as heat shock, chilling, and exposure to stress-related chemicals, was also studied. Heat shock strongly inhibited the expression of the NnMSD1 gene, whereas the NnMSD1 transcript level increased strongly in chilling stress treatment. An increase in expression was also highly induced by H2O2 in germinating embryonic axes. The results suggest that the expression pattern of the NnMSD1 gene differed between developing axes and cotyledons, and that the NnMSD1 gene expression responds strongly to chilling and oxidative stress.
从荷花（Nelumbo nucifera Gaertn.）的胚轴中鉴定出一个锰超氧化物歧化酶（Mn-SOD）基因NnMSD1。NnMSD1蛋白包含Mn-SOD蛋白家族的所有保守残基，包括四个共有金属结合结构域和一个用于线粒体靶向的信号肽。Southern杂交分析表明荷花中存在两个Mn-SOD基因。NnMSD1在种子发育过程中发育中的胚轴中高度表达，但仅在发育早期出现在子叶中，在胚胎发育后期在子叶中无法检测到。还研究了NnMSD1基因在萌发胚轴中对各种胁迫（如热激、冷害和暴露于胁迫相关化学物质）的响应。热激强烈抑制NnMSD1基因的表达，而在冷害胁迫处理中NnMSD1转录水平强烈增加。在萌发胚轴中，H2O2也高度诱导表达增加。结果表明，NnMSD1基因在发育中的胚轴和子叶中的表达模式不同，并且NnMSD1基因表达对冷害和氧化胁迫有强烈响应。
