Increased root hair density by loss ofWRKY6inArabidopsis thaliana.
Root hairs are unicellular elongations of certain rhizodermal cells that improve the uptake of sparingly soluble and immobile soil nutrients. Among differentArabidopsis thalianagenotypes, root hair density, length and the local acclimation to low inorganic phosphate (Pi) differs considerably, when analyzed on split agar plates. Here, genome-wide association fine mapping identified significant single nucleotide polymorphisms associated with the increased root hair density in the absence of local phosphate on chromosome 1. Aloss-of-functionmutant of the candidate transcription factor geneWRKY6, which is involved in the acclimation of plants to low phosphorus, had increased root hair density. This is partially explained by a reduced cortical cell diameter inwrky6-3, reducing the rhizodermal cell numbers adjacent to the cortical cells. As a consequence, rhizodermal cells in positions that are in contact with two cortical cells are found more often, leading to higher hair density. Distinct cortical cell diameters and epidermal cell lengths distinguish otherArabidopsisaccessions with distinct root hair density and -Piresponse from diploid Col-0, while tetraploid Col-0 had generally larger root cell sizes, which explain longer hairs. A distinct radial root morphology withinArabidopsisaccessions andwrky6-3explains some, but not all, differences in the root hair acclimation to -Pi.
Institute of Crop Science, Nutritional Crop Physiology, University of Hohenheim, Stuttgart, Germany; Institute of Plant Breeding, Seed Science and Population Genetics, University of Hohenheim, Stuttgart, Germany.
Markus G
MG
Stetter
Institute of Crop Science, Nutritional Crop Physiology, University of Hohenheim , Stuttgart , Germany.
Martin
M
Benz
Institute of Crop Science, Nutritional Crop Physiology, University of Hohenheim , Stuttgart , Germany.
Uwe
U
Ludewig
Arabidopsis; Cortex; Ecotypes; Epidermis; Genome wide association; Inorganic phosphate; Mixed model; Nutrition; Phosphorus; Root hair