Dependence of root parasitic plants on host-derived strigolactones

独脚金内酯（SLs）是一类调节植物结构的植物激素，也是已知的共生和寄生的根源信号。本研究考察了由SLs触发种子萌发的根寄生植物Striga hermonthica是否产生SLs，以及寄主提供的SLs对其形态的影响。在独立于寄主的琼脂上生长的Striga植株中，SL的水平低于LC-MS分析的检出限，而在Striga植株中检测到的SL光谱与各自寄主的光谱一致。在缺硫水稻突变体上生长的曲条藻叶片在形状和数量上都出现了异常。这些结果表明，寄生体中SL的产生非常有限，寄主植物提供的SL不仅能调节寄生体种子的萌发，还能调节寄生体的形态。

Strigolactones (SLs) are a class of plant hormones that regulate plant architecture as well as being known as root-derived signals for symbiosis and parasitism. This study examined 1) whether Striga hermonthica, a root parasitic plant, whose seed germination is triggered by SLs, produces SLs, and 2) the effect of SLs provided by the host on morphology of the parasite. The level of SLs in Striga plants growing on agar, independent of host, was below the detection limit of LC-MS analysis while SL spectra detected in Striga plants were consistent with those in their respective hosts. Striga plants growing on SL-deficient rice mutants formed leaves abnormal in shape and number. These results suggest that SL production in Striga, if any, is very limited and that SLs provided by host plants regulate not only germination of Striga seeds but also the parasite morphology.