Unleashing the potential of the root hair cell as a single plant cell type model in root systems biology

Abstract

Plant root is an organ composed of multiple cell types with different functions. This multicellular complexity limits our understanding of root biology because -omics studies performed at the level of the entire root reflect the average responses of all cells composing the organ. To overcome this difficulty and allow a more comprehensive understanding of root cell biology, an approach is needed that would focus on one single cell type in the plant root. Because of its biological functions (i.e., uptake of water and various nutrients; primary site of infection by nitrogen-fixing bacteria in legumes), the root hair cell is an attractive single cell model to study root cell response to various stresses and treatments. To fully study their biology, we have recently optimized procedures in obtaining root hair cell samples. We culture the plants using an ultrasound aeroponic system maximizing root hair cell density on the entire root systems and allowing the homogeneous treatment of the root system. We then isolate the root hair cells in liquid nitrogen. Isolated root hair yields could be up to 800 to 1000~mg of plant cells from 60 root systems. Using soybean as a model, the purity of the root hair was assessed by comparing the expression level of genes previously identified as soybean root hair specific between preparations of isolated root hair cells and stripped roots, roots devoid in root hairs. Enlarging our tests to include other plant species, our results support the isolation of large quantities of highly purified root hair cells which is compatible with a systems biology approach.

Divergent cytosine DNA methylation patterns in single‐cell, soybean root hairs

“…Although cell‐type‐specific methylomes of epidermis, cortex, endodermis, stele and columella have been reported in Arabidopsis , root hairs are quite different from these root cell types. Root hairs are an intact single plant cell type (Libault et al ., ,b; Qiao & Libault, ; Hossain et al ., ) originated from the outer layer of the root epidermis, provide a large surface area and are a vital organ for water and mineral uptake. Therefore, they may be more sensitive to environmental stress relative to the entire root organ.…”

The GmFWL1 (FW2‐2‐like) nodulation gene encodes a plasma membrane microdomain‐associated protein

“…Soybean seeds were surface-sterilized according to Wan et al (2005) (Wan et al 2005) then sowed on pro-mix. Ten days after transformation, the transgenic plants were transferred into the ultrasound aeroponic system (Qiao & Libault 2013). When required, 3 weeks old transgenic soybean root system were treated with nitrogen-free B & D solution (Broughton & Dilworth 1971) or by a suspension of B. japonicum (OD 600 = 0.1) (Qiao & Libault 2013).…”

A Comparative Epigenomic Analysis of Polyploidy-Derived Genes in Soybean and Common Bean

“…Soybean root tissues were isolated at the University of Oklahoma as described (Wan et al, 2005;Qiao and Libault, 2013). Briefly, seeds were surface sterilized and were sown on a 3:1 mixture of vermiculite and perlite.…”