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作 者 ：邱龙,熊君,王海斌,方长旬,何海斌,李兆伟,林文雄

期 刊 ：生态学报 2008年 28卷 2期 页码：677~684

关键词：植物养分；化感作用；N素效率；基因表达；水稻；

Keywords:plant nutrient, allelopathy, nitrogen nutrient efficiency, gene expression, Oryza sativa L.,

摘 要 ：为了阐明养分水平引起水稻(Oryza sativa L.)化感抑草潜力变化的生理生态机制，研究了不同N素营养处理下，不同化感潜力水稻苗期对N素营养逆境的响应特性及N素养分效率的差异，并运用实时荧光定量RT-PCR技术（FQ-PCR）检测与N素代谢和次生代谢关键酶的基因表达。结果表明：弱化感水稻品种Lemont对N素营养胁迫较敏感，强化感水稻品种PI312777对资源波动的适应性较强，N素养分效率较高。FQ-PCR分析结果显示，在低N条件下Lemont中的亚硝酸还原酶基因（nir），谷氨酰胺合成酶基因（gs）相对表达量均有不同幅度的下调， PI312777分别下调了1.2倍和1.4倍，而Lemont分别下调了3.0倍和1.8倍， Lemont下调的幅度分别是PI312777的2.5倍和1.3倍，但对于苯丙氨酸解氨酶基因（pal）与3-羟基-3甲基戊二酰辅酶A还原酶基因(hmgr)而言， PI312777叶组织中的pal和hmgr均上调表达,与对照相比上调了6.0倍和1.6倍，而Lemont中对应的基因均下调表达,分别下调了1.3倍和6.8倍，佐证了上述差异的分子生态学特性。

Abstract:Plant allelopathy was a very complicatedly chemoecological phenomenon, which was significantly mediated by ecological factors, such as N nutrient, one of the important factors. In order to explore the inducible mechanism by N nutrient, which markedly affected allelopathic potential in the suppression on the target weeds, we studied the changes in morphological characters of allelopathic rice PI312777 and its counterpart Lemont in the responses to different N supplies and their differences in N nutrient efficiency at the seedling stage, in turn we further detected the differential expressions of the key genes, which were involved in N metabolism and secondary substance synthesis in the two rice varieties concerned using real time quantitative PCR(FQ-PCR). The results indicated that allelopathic rice PI312777 was more insensitive to the nutrient stress than non-allelopathic rice Lemont, performing its stronger adaptable ability and higher N nutrient efficiency especially in lower N supplies. The results obtained form the real time quantitative PCR showed that the relative gene expression quantity of nitrite reductase(nir) and gstamine synthetase(gs) in the leaves of the two rice cultivars were decreased to different extent, indicating that the two gene expressions were down-regulated by 1.2 and 1.4 fold times in allelopathic rice PI312777, and they were also decreased by 3.0 and 1.8 fold times respectively in its counterpart Lemont under lower nitrogen supplies. The decreased ranges of the two genes in non-allelopathic rice Lemont were 2.5 and 1.3 fold times as those in allelopathic rice PI312777. Different trend were observed in the case of phenylalanine ammonia-lyase(pal) and 3-hydroxy-3-methylgstaryl-CoA reductase(hmgr) concerned, which were the key enzymes in phenylalanine and isoprenoids metabolic pathway, indicating that the gene expression of the two key enzymes in the leaves of PI312777 under lower nitrogen condition was up-regulated by 6.0 and 1.6 times respectively compared with the control under normal nitrogen condition. The reverse was true in non-allelopathic rice Lemont, showing that the gene expressions of the two enzymes, i.e. PAL and HMGR in the leaves of Lemont under lower nitrogen condition were down-regulated by 1.3 and 68 fold times as those under normal nitrogen supplies. These findings suggested that allelopathic rice was characterized by its active molecular ecological properties especially in the responses to lower nitrogen stress.

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