DOI: 10.5061/dryad.x3ffbg7q8
title: Data from: Synergistic effects of canopy chemistry and autogenic soil biota on a global invader

description: Soil biota have strong effects on plants, but we have a poor understanding
 of how plant chemistry might modify these effects. We examined the effect
 of soil biota associated with an exotic invasive tree, Prosopis juliflora,
 vs. that associated with native species, from seven sites across India on
 conspecifics and two other plant species. We then measured changes in
 species-specific soil biota effects (identified as plant-soil feedbacks,
 PSFs) when leaf leachate from P. juliflora or from native plant species
 was added to soil containing respective live and sterile soil inoculum. We
 quantified the amino acid L-tryptophan from leaf leachate of P. juliflora,
 Leucaena leucocephala (another invader), and two native species. We also
 tested effects of P. juliflora or native species soil inoculum amendment
 of tryptophan on P. juliflora, P. cineraria, and L. leucocephala across
 seven sites. We then quantified the microbially metabolized derivatives of
 tryptophan, phytohormone indole-3-acetic acid (IAA), and intermediates
 after adding tryptophan into P. juliflora and native soils. Soil biota
 associated with P. juliflora generated positive effects on conspecifics
 and L. leucocephala, but negative effects on the native congener P.
 cineraria. When P. juliflora leaf leachate was added to soil with live P.
 juliflora inoculum, PSFs became more positive for P. juliflora and other
 species, compared to leaf leachate-amended with sterile soil inoculum.
 Native leaf leachate interacted weakly with soil biota to impact biomass
 of conspecifics and heterospecifics.   There was roughly 10x more
 tryptophan in the leaf leachate of P. juliflora than in the leaf leachate
 of other species. Tryptophan generally increased positive PSFs associated
 with P. juliflora relative to soil biota associated with other plant
 species. When tryptophan was added to live P. juliflora soil, IAA and its
 intermediates were produced at five of seven sites, and at four of these
 sites soil biota from P. juliflora had positive PSFs. Synthesis. These
 results provide the first experimental evidence that a chemical leached
 from the leaves of an invader regulates PSFs. Our results indicate that
 canopy effects and PSFs, which are usually studied independently, can
 interact in ways that strongly affect conspecifics and neighbouring
 species.
description: Experiment 1:
 Seedlings were harvested
 and total biomass was recorded following 56 days of growth after oven
 drying for 48 h at 60°C. Experiment 2: Seedlings were harvested and total biomass was
 recorded following 90 days of growth after oven drying for 48 h at
 60°C. Experiment 3: Leaves of <em>Prosopis
 juliflora, Leucaena leucocephala, Prosopis cineraria, </em>and
 <em>Acacia leucophloea</em> were used to prepare the aqueous
 leaf leachates for quantifying tryptophan with ultra-high-pressure liquid
 chromatography (UHPLC). Experiment 4: Seedlings were harvested and total
 biomass was recorded following 56 days of growth after oven drying for 48
 h at 60°C. Experiment 5: Quantification of tryptophan, IAA
 and its intermediates at 0 or 6 days after the addition of
 tryptophan (300 μg/g soil) or sterile water (control) into soils
 associated with <em>Prosopis juliflora</em> or native species
 from seven sites.