---

作 者 ：王海斌;熊君;方长旬;邱龙;吴文祥;何海斌;林文雄

期 刊 ：作物学报 2007年 33卷 08期 页码：1329-1334

关键词：水稻；异戊二烯途径；FQ-PCR；氮素；

Keywords:Rice (Oryza Sativa L.), isoprenoids metabolic pathway, FQ-PCR, nitrogen stress,

摘 要 ：

运用实时荧光定量PCR技术研究低氮条件下化感与非化感水稻异戊二烯代谢途径中关键酶基因的表达差异。结果表明，与正常氮条件下相比，低氮条件下化感和非化感水稻与萜类物质合成相关的12个关键酶基因表达发生了不同程度的变化，其中，化感水稻PI312777有6个基因表达下调，6个基因则上调；而非化感水稻Lemont有7个基因表达下调，5个基因表达上调。在供氮条件从高向低改变的过程中，两水稻中有11个基因的表达行为（上调或下调）相同，从分子水平上，证实了它们萜类代谢相关基因在响应供氮环境变化的行为生态上是相同或相似的。低氮引起两水稻催化生成与化感物质相关的单萜、倍半萜、二萜、三萜类物质的合成酶基因表达量均显著下降，从而认为营养胁迫引起水稻化感抑草作用增强与萜类物质代谢变化无关。还讨论了营养胁迫引起萜类物质代谢变化与内源激素合成和生长速率减缓的关系，认为水稻甲羟戊酸代谢途径支路中3-羟基-3-甲基戊二单酰CoA合酶、3-羟基-3-甲基戊二单酰CoA还原酶和甲羟戊酸激酶相关基因表达量不同程度的上调，维持了生长所必需的激素水平。

Abstract:

The differential expression of the key genes controlling isoprenoid metabolism in allelopathic and weak allelopathic rice accessions was investigated under two nitrogen supply levels using fluorescence quantitative polymerase chain reaction（FQ-PCR）. The results indicated that 12 detected key enzyme genes were mediated by lower nitrogen level. Of the twelve genes, six were up-regulated, and the others were down-regulated in allelopathic rice accession. In weak allelopathic rice Lemont, seven were up-regulated and five down-regulated. Of 12 tested genes, six up-regulated genes and five down-regulated genes detected in allelopathic rice PI312777 were founded in weak allelopathic rice Lemont. In other words, 11 out of 12 key genes involved in isoprenoid metabolic pathway in the two rice accessions had the same gene expression patterns under low nitrogen condition compared with the controls, suggesting that the related genes involved in isoprenoid metabolic pathway possessed the same or the similar ecological behavior in response to the changes of nitrogen supplies in the molecular scale. The further analysis showed that lower nitrogen supplies led to significantly declined expression of the key genes related to monoterpene, sesquiterpene, diterpene and triterpene. In conclusion, the increase of allelopathic potential induced by nutrient stress is not responsible for the variation of the terpenoid metabolism. It was also discussed that the relationships possibly existed among terpenoid synthesis decrease, hormone synthesis reduction and the plant growth inhibition, which in turn resulted in to a great extent, increased expression of the three genes encoding 3-hydroxy-3-methylglutaryl-CoA synthase, 3-hydroxy-3-methylglutaryl-CoA reductase and mevalonate kinase in the branch of mevalonate metabolism to sustain essential level of hormone for rice growth under nutrient stress condition.

---