Complexity and specificity of the maize (Zea mays L.) root hair transcriptome

Stefan Hey,Frank Hochholdinger,Nina Opitz,Andrew Lithio,Nicholas Provart,Asher Pasha,Dan Nettleton,Jutta Baldauf

doi:10.1093/jxb/erx104

Stefan Hey, Frank Hochholdinger + Show 6 more

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https://doi.org/10.1093/jxb/erx104

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Abstract

Root hairs are tubular extensions of epidermis cells. Transcriptome profiling demonstrated that the single cell-type root hair transcriptome was less complex than the transcriptome of multiple cell-type primary roots without root hairs. In total, 831 genes were exclusively and 5585 genes were preferentially expressed in root hairs [false discovery rate (FDR) ≤1%]. Among those, the most significantly enriched Gene Ontology (GO) functional terms were related to energy metabolism, highlighting the high energy demand for the development and function of root hairs. Subsequently, the maize homologs for 138 Arabidopsis genes known to be involved in root hair development were identified and their phylogenetic relationship and expression in root hairs were determined. This study indicated that the genetic regulation of root hair development in Arabidopsis and maize is controlled by common genes, but also shows differences which need to be dissected in future genetic experiments. Finally, a maize root view of the eFP browser was implemented including the root hair transcriptome of the present study and several previously published maize root transcriptome data sets. The eFP browser provides color-coded expression levels for these root types and tissues for any gene of interest, thus providing a novel resource to study gene expression and function in maize roots.

Highlights

Root hairs are tubular outgrowths of single epidermal cells instrumental for nutrient uptake and optimal plant development (Gilroy and Jones, 2000)
This study indicated that the genetic regulation of root hair development in Arabidopsis and maize is controlled by common genes, and shows differences which need to be dissected in future genetic experiments
Tissue-specific transcriptomic dynamics have been determined for maize root tissues (Paschold et al, 2014; Baldauf et al, 2016; Opitz et al, 2016), on the level of single cell types in Arabidopsis (Birnbaum et al, 2003; Brady et al, 2007; Dinneny et al, 2008), and individual root cell types of monocots such as pericycle cells of maize (Woll et al, 2005; Dembinsky et al, 2007; Yu et al, 2016a)

Summary

Introduction

Root hairs are tubular outgrowths of single epidermal cells instrumental for nutrient uptake and optimal plant development (Gilroy and Jones, 2000). The epidermis of plant roots comprises two types of cells: trichoblasts and atrichoblasts. In maize and some other monocots, most ferns, and most dicots, type I root hair patterning occurs, in which any root epidermis cell can randomly form a root hair. In type II root hair patterning, root hairs develop from the smaller cell of an asymmetric division. This type is implemented among early land plants, some monocot species, including rice, and the dicot family Nymphaeaceae.

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