Molecular mechanisms of biosynthesis and exudation of strigolactones and their manipulation for regulation of parasitism and symbiosis

植物根部分泌物Strigollacones能诱导根部寄生植物种子萌发，诱导共生丛枝菌根真菌(AM)的菌丝分枝。因此，植物内酯类化合物是寄生和共生的寄主识别信号。对马立内酯的生物合成和渗出的分子机制进行了研究。通过这些研究，1)分离并鉴定了几种新的植物内酯，2)阐明了营养物质对植物内酯合成和分泌的影响，3)阐明了植物内酯在促进根寄生杂草种子萌发和诱导AM真菌菌丝分枝中的构效关系，4)研究了根寄生植物与其亲和寄主植物和不亲和寄主植物之间的相互作用。此外，水稻植株过多的分枝突变体，无论是在生物合成上还是在信号转导上都存在缺陷，这表明稻枝内酯是一类新的抑制枝条分枝的植物激素。

Strigolactones exuded from plant roots elicit seed germination of root parasitic plants and induce hyphal branching of symbiotic arbuscular mycorrhizal (AM) fungi. Therefore, strigolactones function as host recognition signals for both parasitism and symbiosis. Studies were conducted to understand molecular mechanisms of strigolactone biosynthesis and exudation. Through the studies, 1) several novel strigolactones were isolated and their structures determined, 2) effects of nutrients on strigolactone production and exudation were clarified, 3) structure-activity relationships of strigolactones in germination stimulation of root parasitic weed seeds and in induction of hyphal branching of AM fungi were elucidated, and 4) interactions between root parasitic plants with their compatible and incompatible host plants were examined. In addition, excessive branching mutants of rice plants were found to be the deficit either in biosynthesis or signal transduction of strigolactones, demonstrating that strigolactones are a novel class of plant hormones inhibiting shoot branching.