Transfer of photosynthate and naturally occurring insecticidal compounds from host plants to the root hemiparasite Santalum acuminatum(Santalaceae)

Abstract

Plant hemiparasites obtain a wide range of primary compounds from their host plants, including carbon, water and ions. In this paper, we examine the transfer of carbon from the host plant Myoporum parvifolium and the movement of an insecticidal compound from the host Melia azedarach to the root hemiparasite Santalum acuminatum(R.Br) (quandong). By using ¹⁴ C we determined that glucose was moving from the M. parvifolium host to the parasite while the carbon fixed by quandongs was found to be mostly in mannitol. Mannitol occurred in fruit, leaf, stem and root tissue and also in xylem sap. We also provide evidence from direct infusion electrospray mass spectrometry (DIEMS) that quandong fruit from trees growing near Melia azedarach (L.) contain an insecticidal compound. This was supported by results from a bioassay in which apple moth (Epiphyas postvittana Wal ker) larvae suffered higher mortality when fed only on quandong fruit that was growing nearM. azedarach than those fed on quandong fruit from trees growing away from M. azedarach.