Germination strategy of Striga hermonthica involves regulation of ethylene biosynthesis
Germination strategy of Striga hermonthica involves regulation of ethylene biosynthesis
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DOI：
10.1034/j.1399-3054.2003.00162.x
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发表时间：
2003-09-01
影响因子：
6.4
通讯作者：
Itai, A
中科院分区：
文献类型：
--
作者：
Sugimoto, Y;Ali, AM;Itai, A
乙烯对水曲菌萌发的影响Benth。摘要从生理和分子水平研究了水煮作物上重要的根寄生杂草。种子在30℃条件下放置14 d，分别用乙烯、乙烯利或1-氨基环丙烷-1-羧酸（ACC）处理。乙烯始终诱导低发芽率。乙烯利和ACC分别在0.01 mM和1 mM浓度下有效促进萌发。与乙烯相反，乙烯利和ACC都以浓度依赖的方式起作用。合成的独角曲内酯GR24的萌发受到氨基乙氧基乙烯基甘氨酸（AVG）和1-甲基环丙烯的抑制。当种子在密封的小瓶中用GR24处理时，顶空气体中的乙烯浓度在萌发开始前就增加了。GR24处理12 h后，从萌发种子中提取总RNA，利用pcr扩增编码ACC合成酶和氧化酶活性位点域的cDNA片段。对编码ACC合成酶的两个不同cDNA片段（SHACS1和SHACS2）和编码ACC氧化酶的一个片段（SHACO1）进行了克隆和测序。Southern的分析表明，克隆的每一个基因都以一个拷贝的形式存在于S. hermonthica基因组中。Northern分析表明，在GR24处理后10 h， SHACS1的表达出现了时间变化，这与乙烯浓度的稳定增加相吻合。SHACS2表达水平较低，表达趋势相似。SHACO1的表达量在调质后第15天达到峰值，此时种子对GR24的反应最为强烈。综上所述，ACC合成酶和ACC氧化酶基因的表达分别对萌发刺激物和条件作用有响应。本文还讨论了这些研究结果在田间条件下对山楂发芽的影响。
Ethylene involvement in germination of Striga hermonthica (Del.) Benth., an important root parasitic weed on poaceous crops, was investigated at the physiological and molecular levels. Seeds, conditioned at 30degreesC for 14 days, were treated with ethylene, ethephon or 1-aminocyclopropane-1-carboxylic acid (ACC). Ethylene consistently induced low germination. Ethephon and ACC effectively stimulated germination at concentrations of 0.01 and 1 mM, respectively. In contrast to ethylene, both ethephon and ACC acted in a concentration-dependent manner. Germination induced by the synthetic strigolactone GR24 was inhibited by aminoethoxyvinylglycine (AVG) and 1-methylcyclopropene. ACC reversed the inhibition caused by AVG. When seeds were treated with GR24 in sealed vials, ethylene concentration in headspace gas increased prior to the onset of germination. Total RNA extracted from germinating seeds 12 h after GR24 treatment was used for PCR-based amplification of cDNA fragments encoding the ACC synthase- and oxidase-active site domains. Two distinct cDNA fragments encoding ACC synthase (SHACS1 and SHACS2) and one encoding ACC oxidase (SHACO1) were cloned and sequenced. Southern analysis suggested that each of the cloned genes was present as a single copy in the genome of S. hermonthica. Northern analyses showed that SHACS1 exhibited a temporal change in expression peaking at 10 h after GR24 treatment, which coincided with a steady increase in ethylene concentration. SHACS2 was expressed at a low level with a similar trend. SHACO1 exhibited a temporal change in expression peaking at 15 days during conditioning, when seed response to GR24 was maximal. In summary, expression of ACC synthase and ACC oxidase genes was found to be responsive to a germination stimulant and to conditioning, respectively. The implications of these findings with respect to germination of S. hermonthica under field conditions are discussed.