Removal of soil biota alters soil feedback effects on plant growth and defense chemistry

• Published in: The New phytologist Vol. 221; no. 3; pp. 1478 - 1491
• Main Authors: Wang, Minggang, Ruan, Weibin, Kostenko, Olga, Carvalho, Sabrina, Hannula, S. Emilia, Mulder, Patrick P. J., Bu, Fengjiao, van der Putten, Wim H., Bezemer, T. Martijn
• Format: Journal Article
• Language: English
• Published: England Wiley 01.02.2019; Wiley Subscription Services, Inc; John Wiley and Sons Inc
• Subjects: Alkaloids; Bacteria; Bacteria - metabolism; Biomass; Biota; chemistry; Composition; Conditioning; Europe; fauna; Feedback; fractionation; Fungi; Fungi - physiology; Herbivores; Herbivory; Inoculum; Insects; Jacobaea vulgaris; leaves; Macrofauna; Markvetenskap; Negative feedback; Organic chemistry; Outbreaks; Pest outbreaks; phytomass; phytophagous insects; Plant biomass; Plant Development; Plant growth; Plant species; plant–soil feedback (PSF); Principal Component Analysis; Pyrrolizidine alkaloids; pyrrolizidine alkaloids (PAs); Reflectance; Removal; sieving; Soil; soil biota; Soil conditions; Soil Science; soil sterilization; soil-plant interactions; Soils; spectral reflectance; Stress, Physiological; Water; Zoobenthos; Europe; fractionation; spectral reflectance; soil biota; Jacobaea vulgaris; plant-soil feedback (PSF); pyrrolizidine alkaloids (PAs)
• ISSN: 0028-646X; 1469-8137; 1469-8137
• DOI: 10.1111/nph.15485

• We examined how the removal of soil biota affects plant–soil feedback (PSF) and defense chemistry of Jacobaea vulgaris, an outbreak plant species in Europe containing the defense compounds pyrrolizidine alkaloids (PAs). • Macrofauna and mesofauna, as well as fungi and bacteria, were removed size selectively from unplanted soil or soil planted with J. vulgaris exposed or not to above- or belowground insect herbivores. Wet-sieved fractions, using 1000-, 20-, 5- and 0.2-μm mesh sizes, were added to sterilized soil and new plants were grown. Sieving treatments were verified by molecular analysis of the inocula. • In the feedback phase, plant biomass was lowest in soils with 1000- and 20-μm inocula, and soils conditioned with plants gave more negative feedback than without plants. Remarkably, part of this negative PSF effect remained present in the 0.2-μm inoculum where no bacteria were present. PA concentration and composition of plants with 1000- or 20-μm inocula differed from those with 5- or 0.2-μm inocula, but only if soils had been conditioned by undamaged plants or plants damaged by aboveground herbivores. These effects correlated with leaf hyperspectral reflectance. • We conclude that size-selective removal of soil biota altered PSFs, but that these PSFs were also influenced by herbivory during the conditioning phase.