Sorghum is considered an allelopathic crop species and sorgoleone likely accounts for much of its allelopathic properties. Prior investigations into the biosynthesis of sorgoleone suggested the participation of one or more alkylresorcinol synthases (ARS), which are type III polyketide synthases (PKS) that produce 5-alkylresorcinols using medium to long-chain fatty acyl-CoA starter units via iterative condensations with malonyl-CoA. Quantitative real-time RT-PCR analysis of PKS-like sequences mined from isolated root hairs revealed that two sequences, designated ARS1 and ARS2, were preferentially expressed. Recombinant enzyme studies demonstrated that both sequences encode ARS enzymes capable of accepting a variety of fatty acyl-CoA starter units. RNA interference (RNAi) experiments directed against ARS1 and ARS2 resulted in the generation of multiple independent transformant events exhibiting dramatically reduced sorgoleone levels. Thus, both ARS1 and ARS2 participate in the biosynthesis of sorgoleone in planta. ARS1 and ARS2 sequences were used to identify rice genes encoding alkylresorcinol synthases.
高粱被认为是一种化感作物,其中sorgoleone很可能占据了其大部分化感性能。关于sorgoleone
生物合成的先前研究表明,涉及到一种或多种烷基
间苯二酚合酶(ARS),它们是III型多酮合酶(PKS),通过与马来酰辅酶进行迭代缩合反应,使用中长链脂肪酰辅酶起始单元产生5-烷基
间苯二酚。从分离的根毛中挖掘出的PKS类似序列的定量实时RT-PCR分析表明,有两个序列,分别命名为ARS1和ARS2,被优先表达。
重组酶研究表明,这两个序列都编码能够接受各种脂肪酰辅酶起始单元的ARS酶。针对ARS1和ARS2的RNA干扰(RNAi)实验导致产生多个独立的转化事件,这些事件表现出显著降低的sorgoleone
水平。因此,ARS1和ARS2都参与了植物中sorgoleone的
生物合成。ARS1和ARS2序列被用于鉴定编码烷基
间苯二酚合酶的
水稻
基因。