RIKEN Center for Sustainable Resource Science, Yokohama, 230-0045, Japan.
Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Nara, 630-0192, Japan.
Nat Commun. 2022 Aug 15;13(1):4653. doi: 10.1038/s41467-022-32314-z.
Parasitic plants are worldwide threats that damage major agricultural crops. To initiate infection, parasitic plants have developed the ability to locate hosts and grow towards them. This ability, called host tropism, is critical for parasite survival, but its underlying mechanism remains mostly unresolved. To characterise host tropism, we used the model facultative root parasite Phtheirospermum japonicum, a member of the Orobanchaceae. Here, we show that strigolactones (SLs) function as host-derived chemoattractants. Chemotropism to SLs is also found in Striga hermonthica, a parasitic member of the Orobanchaceae, but not in non-parasites. Intriguingly, chemotropism to SLs in P. japonicum is attenuated in ammonium ion-rich conditions, where SLs are perceived, but the resulting asymmetrical accumulation of the auxin transporter PIN2 is diminished. P. japonicum encodes putative receptors that sense exogenous SLs, whereas expression of a dominant-negative form reduces its chemotropic ability. We propose a function for SLs as navigators for parasite roots.
寄生植物是对全球农业作物造成损害的重大威胁。为了启动感染，寄生植物已经发展出定位宿主并向其生长的能力。这种能力被称为寄主向性，对寄生虫的生存至关重要，但它的潜在机制在很大程度上仍未得到解决。为了描述寄主向性，我们使用了模式兼性根寄生植物 Phtheirospermum japonicum，它是列当科的一员。在这里，我们表明独脚金内酯（SLs）作为宿主来源的化感引诱剂发挥作用。Striga hermonthica 对 SLs 的趋化性也存在于 Orobanchaceae 寄生成员中，但在非寄生植物中不存在。有趣的是，P. japonicum 对 SLs 的化感作用在富含铵离子的条件下减弱，在这种条件下会感知到 SLs，但生长素转运蛋白 PIN2 的不对称积累减少。P. japonicum 编码了感知外源性 SLs 的假定受体，而显性负形式的表达降低了其趋化能力。我们提出了 SLs 作为寄生虫根导航的功能。
