An Inventory of Nutrient-Responsive Genes in Arabidopsis Root Hairs.

Jorge E Salazar-Henao,Wolfgang Schmidt

doi:10.3389/fpls.2016.00237

Abstract

Root hairs, single cell extensions of root epidermal cells that are critically involved in the acquisition of mineral nutrients, have proven to be an excellent model system for studying plant cell growth. More recently, omics-based systems biology approaches have extended the model function of root hairs toward functional genomic studies. While such studies are extremely useful to decipher the complex mechanisms underlying root hair morphogenesis, their importance for the performance and fitness of the plant puts root hairs in the spotlight of research aimed at elucidating aspects with more practical implications. Here, we mined transcriptomic and proteomic surveys to catalog genes that are preferentially expressed in root hairs and responsive to nutritional signals. We refer to this group of genes as the root hair trophomorphome. Our analysis shows that the activity of genes within the trophomorphome is regulated at both the transcriptional and post-transcriptional level with the mode of regulation being related to the function of the gene product. A core set of proteins functioning in cell wall modification and protein transport was defined as the backbone of the trophomorphome. In addition, our study shows that homeostasis of reactive oxygen species and redox regulation plays a key role in root hair trophomorphogenesis.

Highlights

Root hairs are the major site for the acquisition of mineral nutrients from the soil
In Arabidopsis, root hairs develop from specialized epidermal cells that are located over the anticlinal walls of two underlying cortical cells
The positional-biased cell fate determination leads to longitudinally oriented files of root hair-bearing cells that are interspersed with non-hair cell files (Dolan et al, 1994; Cederholm et al, 2012; Petricka et al, 2012a)

Summary

INTRODUCTION

Root hairs are the major site for the acquisition of mineral nutrients from the soil. Signal strength, which is influenced by the arrangement of epidermal cells and several feedback loops that increases SCM abundance in trichoblasts, tips the balance of the distribution of two WD-repeat/bHLH/Myb transcriptional complexes that act either as inhibitor or as activator of the root hair cell fate (Kwak and Schiefelbein, 2008, 2014) Subtle changes in this balance leads to accumulation of. Intron retention often leads to the inclusion of premature termination codons and subsequence degradation of the mRNA via the nonsense-mediated decay RNA surveillance pathway (Drechsel et al, 2013) In support of this supposition, transcripts derived from genes that are tightly co-expressed in root hairs and likely to be critically involved in root hair morphogenesis showed less pronounced intron retention (i.e., higher splicing fidelity) than genes that were not coregulated (Lan et al, 2013). This survey revealed a set of nutrient-responsive root hair genes, here designated as the “trophomorphome” that are critically involved in altering root hair morphogenesis to tune developmental programs to the prevailing conditions

RESULTS AND DISCUSSION

CONCLUSIONS

MATERIALS AND METHODS