Establishment of a Protein Reference Map for Soybean Root Hair Cells    

Abstract

Root hairs are single tubular cells formed from the differentiation of epidermal cells on roots. They are involved in water and nutrient uptake and represent the infection site on leguminous roots by rhizobia, soil bacteria that establish a nitrogen-fixing symbiosis. Root hairs develop by polar cell expansion or tip growth, a unique mode of plant growth shared only with pollen tubes. A more complete characterization of root hair cell biology will lead to a better understanding of tip growth, the rhizobial infection process, and also lead to improvements in plant water and nutrient uptake. We analyzed the proteome of isolated soybean (Glycine max) root hair cells using two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and shotgun proteomics (1D-PAGE-liquid chromatography and multidimensional protein identification technology) approaches. Soybean was selected for this study due to its agronomic importance and its root size. The resulting soybean root hair proteome reference map identified 1,492 different proteins. 2D-PAGE followed by mass spectrometry identified 527 proteins from total cell contents. A complementary shotgun analysis identified 1,134 total proteins, including 443 proteins that were specific to the microsomal fraction. Only 169 proteins were identified by the 2D-PAGE and shotgun methods, which highlights the advantage of using both methods. The proteins identified are involved not only in basic cell metabolism but also in functions more specific to the single root hair cell, including water and nutrient uptake, vesicle trafficking, and hormone and secondary metabolism. The data presented provide useful insight into the metabolic activities of a single, differentiated plant cell type.

Spatio Temporal Influence of Isoflavonoids on Bacterial Diversity in the Soybean Rhizosphere

“…However, rhizodeposition of isoflavonoids occurs through mechanisms other than root exudation as well, e.g., root border cells (Hawes et al 2000). Therefore, silencing components of root exudation machinery (e.g., ABC transporters [Brechenmacher et al 2009;Sugiyama et al 2007]) might not result in efficient depletion of isoflavonoids in rhizodeposits. Similarly, the use of adsorbents might disrupt quorum signals between bacteria and cause nonspecific modifications in root-surface microbial communities and exert unpredicted, indirect impacts on nontarget organisms, including the plant producing the flavonoids (Hassan and Mathesius 2012).…”

Comparative Proteomic Analysis of Soybean Nodulation Using a Supernodulation Mutant, SS2-2

“…For soybean, proteomic analyses to study nodulation have been applied to root hairs, 12,30) root hair-stripped roots, 12) nodule cytosol, 20) nodule mitochondria, 19) the peribacteroid membrane, 17) xylem sap, 21) and apoplast. 21) Although there were many differences in the sampling and harvesting time points for the studies, our proteome images proved to be similar to those of root hairs, root hair-stripped roots, and nodule cytosol and mitochondria, and the lists of proteins identified also partly overlapped.…”

The Root Hair “Infectome” of Medicago truncatula Uncovers Changes in Cell Cycle Genes and Reveals a Requirement for Auxin Signaling in Rhizobial Infection

“…From the first efforts at isolation of proteins and RNA from purified root hairs (Röhm and Werner, 1987;Covitz et al, 1998;Ramos and Bisseling, 2003;Sauviac et al, 2005) to the recent application of different -omics technologies in soybean (Brechenmacher et al, 2009Libault et al, 2010), the advantages of isolating root hairs have been recognized. We analyzed the root hair transcriptome of M. truncatula during rhizobial infection, studying gene expression over a time course.…”