Modification of phenolic metabolism in soybean hairy roots through down regulation of chalcone synthase or isoflavone synthase
Modification of phenolic metabolism in soybean hairy roots through down regulation of chalcone synthase or isoflavone synthase
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DOI：
10.1007/s00425-006-0368-z
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发表时间：
2007-02-01
期刊：
影响因子：
4.3
通讯作者：
Widholm, Jack M.
中科院分区：
文献类型：
--
作者：
Lozovaya, Vera V.;Lygin, Anatoliy V.;Widholm, Jack M.
大豆毛状根，转化与大豆查耳酮合酶（CHS6）或异黄酮合酶（IFS 2）基因，具有显着降低的能力，合成异黄酮的生产，以确定这些变化将对真菌病原体的易感性有什么影响。在大多数品系中，由于基因沉默，雌二醇和香豆雌酚的浓度明显降低了约90%。IFS 2转化系在微粒体组分中具有非常低的IFS酶活性，如通过柚皮素转化为染料木黄酮所测量的。CHS6系的CHS酶活性比适当的对照低5至20倍。与对照相比，IFS 2和CHS转化的系积累了更高浓度的可溶性和细胞壁结合的酚酸，在CHS6系中发现了更高的水平，表明途径的木质素生物合成分支发生了改变。大豆植物抗毒素大豆抗毒素的前体是大豆苷元，由真菌病原体Fusarium solani f.大豆猝死综合征（SDS）的病原大豆根瘤菌（FSG）的研究表明，低转化率的转化株系不积累大豆抗毒素，而对照株系积累大豆抗毒素。在IFS 2转化的根中，（异）甘草素含量在FSG诱导后增加，表明在此点之前的途径反应可以控制甘草素的合成。真菌在毛状根上的生长速率最低的是FSG部分抗性对照根，其次是SDS敏感对照根和低转化率转化体。结果表明植物抗毒素的合成在根系抗病性中的重要性。
Soybean hairy roots, transformed with the soybean chalcone synthase (CHS6) or isoflavone synthase (IFS2) genes, with dramatically decreased capacity to synthesize isoflavones were produced to determine what effects these changes would have on susceptibility to a fungal pathogen. The isoflavone and coumestrol concentrations were decreased by about 90% in most lines apparently due to gene silencing. The IFS2 transformed lines had very low IFS enzyme activity in microsomal fractions as measured by the conversion of naringenin to genistein. The CHS6 lines with decreased isoflavone concentrations had 5 to 20-fold lower CHS enzyme activities than the appropriate controls. Both IFS2 and CHS transformed lines accumulated higher concentrations of both soluble and cell wall bound phenolic acids compared to controls with higher levels found in the CHS6 lines indicating alterations in the lignin biosynthetic branch of the pathway. Induction of the soybean phytoalexin glyceollin, of which the precursor is the isoflavone daidzein, by the fungal pathogen Fusarium solani f. sp. glycines (FSG) that causes soybean sudden death syndrome (SDS) showed that the low isoflavone transformed lines did not accumulate glyceollin while the control lines did. The (iso)liquritigenin content increased upon FSG induction in the IFS2 transformed roots indicating that the pathway reactions before this point can control isoflavonoid synthesis. The lowest fungal growth rate on hairy roots was found on the FSG partially resistant control roots followed by the SDS sensitive control roots and the low isoflavone transformants. The results indicate the importance of phytoalexin synthesis in root resistance to the pathogen.