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Do longer root hairs improve phosphorus uptake? Testing the hypothesis with transgenic Brachypodium distachyon lines overexpressing endogenous RSL genes
Author(s) -
Zhang Chunyan,
Simpson Richard J.,
Kim Chul Min,
Warthmann Norman,
Delhaize Emmanuel,
Dolan Liam,
Byrne Mary E.,
Wu Yu,
Ryan Peter R.
Publication year - 2018
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.14980
Subject(s) - brachypodium distachyon , root hair , brachypodium , biology , biomass (ecology) , genetically modified crops , transgene , endogeny , botany , phosphorus , gene , horticulture , agronomy , biochemistry , chemistry , organic chemistry , genome
Summary Mutants without root hairs show reduced inorganic orthophosphate (Pi) uptake and compromised growth on soils when Pi availability is restricted. What is less clear is whether root hairs that are longer than wild‐type provide an additional benefit to phosphorus (P) nutrition. This was tested using transgenic Brachypodium lines with longer root hairs. The lines were transformed with the endogenous Bd RSL 2 and Bd RSL 3 genes using either a constitutive promoter or a root hair‐specific promoter. Plants were grown for 32 d in soil amended with various Pi concentrations. Plant biomass and P uptake were measured and genotypes were compared on the basis of critical Pi values and P uptake per unit root length. Ectopic expression of RSL 2 and RSL 3 increased root hair length three‐fold but decreased plant biomass. Constitutive expression of Bd RSL 2 , but not expression of Bd RSL 3 , consistently improved P nutrition as measured by lowering the critical Pi values and increasing Pi uptake per unit root length. Increasing root hair length through breeding or biotechnology can improve P uptake efficiency if the pleotropic effects on plant biomass are avoided. Long root hairs, alone, appear to be insufficient to improve Pi uptake and need to be combined with other traits to benefit P nutrition.