Root responses to domestication, precipitation and silicification: weeping meadow grass simplifies and alters toughness
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Background and aims
Plant breeding usually focuses on conspicuous above-ground plant traits, yet roots fundamentally underpin plant fitness. Roots show phenotypic plasticity in response to soil conditions but it is unclear whether domesticated plants respond like their ancestors. We aimed to determine how root traits differed between ancestral and domesticated types of a meadow grass (Microlaena stipoides) under altered regimes of precipitation and soil silicon availability.
We subjected the two grass types to three simulated precipitation regimes (ambient, +50%/deluge and −50%/drought) in soil with (Si+) and without (Si−) silicon supplementation and then characterised root biomass, architectural complexity and toughness in addition to shoot traits.
Domestication increased root tissue density, decreased specific root length (SRL) and decreased root architectural complexity. Domestication also increased root strength under Si− conditions but not Si+ conditions. Fine roots, SRL, architectural complexity and the force required to tear the roots all decreased under deluge. The ancestral and domesticated grasses responded similarly to precipitation, except that the latter had weaker roots (decreased fracture strain) under drought.
Domestication and increased precipitation caused changes in M. stipoides root traits that could be beneficial against some stresses (e.g. soil compaction, herbivory) but not others (e.g. drought).
KeywordsDeluge Drought Fracture strain Root architectural complexity Root trait selection Tensile strength
root tissue density
specific root length
specific root area
This research was funded by a Discovery Project grant from the Australian Research Council (ARC DP140100636) awarded to SNJ and BDM and an internship from the Hawkesbury Institute for the Environment awarded to MC. We would like to thank Dr. I. Chivers (Native Seeds Pty Ltd., Australia) for providing the seeds.
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