Two-way transfer of nitrogen between Dalbergia odorifera and its hemiparasite Santalum album is enhanced when the host is effectively nodulated and fixing nitrogen

Abstract

Nutrient translocation from a host plant is vital to the growth and survival of its root parasitic plant, but few studies have investigated whether a parasitic plant is also able to transfer nutrients to its host. The role of N2-fixation in nitrogen (N) transfer between 7-month-old Dalbergia odorifera T. Chen nodulated with Bradyrhizobium elkanii DG and its hemiparasite Santalum album Linn. was examined by external (15)N labeling in a pot study. Four paired treatments were used, with (15)N given to either host or hemiparasite and the host either nodulated or grown on combined N. N2-fixation supplied 41-44% of total N in D. odorifera. Biomass, N and (15)N contents were significantly greater in both nodulated D. odorifera and S. album grown with paired nodulated D. odorifera. Significantly higher total plant (15)N recovery was in N donor D. odorifera (68-72%) than in N donor S. album (42-44%), regardless of the nodulation status in D. odorifera. Nitrogen transfer to S. album was significantly greater (27.8-67.8 mg plant(-1)) than to D. odorifera (2.0-8.9 mg plant(-1)) and 2.4-4.5 times greater in the nodulated pair than in the non-nodulated pair. Irrespective of the nodulation status, S. album was always the N-sink plant. The amount of two-way N transfer was increased by the presence of effective nodules, resulting in a greater net N transfer (22.6 mg plant(-1)) from host D. odorifera to hemiparasite S. album. Our results may provide N management strategies for D. odorifera/S. album mixed plantations in the field.

A neglected alliance in battles against parasitic plants: arbuscular mycorrhizal and rhizobial symbioses alleviate damage to a legume host by root hemiparasitic Pedicularis species

“…However, the marked effects of dual inoculation (+RH+AMF) on growth of both the host and hemiparasites suggested significant roles of this bacterium in regulating legume–parasite interactions (Figs ; Tables , ). Considering the fact that legumes are preferred hosts for many parasitic plants and are well known to associate with N 2 ‐fixing rhizobia, it is surprising that very few efforts have been made to address the influence of rhizobia on host–parasite interactions (Mabrouk et al ., ; Jiang et al ., ; Lu et al ., ; Cirocco et al ., ). Unfortunately, most of these studies did not include a strict control (i.e.…”

Is nitrogen transfer among plants enhanced by contrasting nutrient‐acquisition strategies?

“…; Lu et al . ). The 15 N pulse‐labelling was undertaken over a 3 week period at the end of the experiment; the end of the ‘chase’ period coincided with the start of the leachate and harvesting (see later).…”

“…; Lu et al . ). However, there remains controversy about whether transfer occurs preferentially via AM networks, ectomycorrhizal (EM) networks, or indirectly through the soil; perhaps because of the very small magnitude of transfers that have been measured via direct pathways (Ikram et al .…”

Does nitrogen affect the interaction between a native hemiparasite and its native or introduced leguminous hosts?

“…Similarly, the root hemiparasite Santalum album grew significantly larger on the nodulated vs nonnodulated host Dalbergia odorifera (Lu et al, 2013; but see Jiang et al, 2008). It appears that, in these studies, hosts grew larger in response to high N or nodulation and so too did the parasites (Lu et al, 2013;Shen et al, 2013). Here, infected plants did not grow larger in HN relative to LN.…”

“…They attributed these decreases to C and N removal by the parasite from the host phloem; however, in this study plants were only supplied with N-free solution. Another study manipulated the nodulation status of Dalbergia odorifera infected with Santalum album, but did not include uninfected plants in the experiment (Lu et al, 2013). Jiang et al (2008) did include uninfected plants in their investigation into the effect of Rhinanthus minor on Vicia faba when colonized or not (provided with inorganic N) with rhizobia.…”