A comprehensive strategy for identifying long-distance mobile peptides in xylem sap

Plant J. 2015 Nov;84(3):611-20. doi: 10.1111/tpj.13015. Epub 2015 Oct 7.

Abstract

There is a growing awareness that secreted pemediate organ-to-organ communication in higher plants. Xylem sap peptidomics is an effective but challenging approach for identifying long-distance mobile peptides. In this study we developed a simple, gel-free purification system that combines o-chlorophenol extraction with HPLC separation. Using this system, we successfully identified seven oligopeptides from soybean xylem sap exudate that had one or more post-transcriptional modifications: glycosylation, sulfation and/or hydroxylation. RNA sequencing and quantitative PCR analyses showed that the peptide-encoding genes are expressed in multiple tissues. We further analyzed the long-distance translocation of four of the seven peptides using gene-encoding peptides with single amino acid substitutions, and identified these four peptides as potential root-to-shoot mobile oligopeptides. Promoter-GUS analysis showed that all four peptide-encoding genes were expressed in the inner tissues of the root endodermis. Moreover, we found that some of these peptide-encoding genes responded to biotic and/or abiotic factors. These results indicate that our purification system provides a comprehensive approach for effectively identifying endogenous small peptides and reinforce the concept that higher plants employ various peptides in root-to-shoot signaling.

Keywords: C-terminally encoded peptide; CLV3/ESR-related; long-distance; peptidomics; sulfated peptide; xylem sap.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Chemical Fractionation / methods
  • Chlorophenols / chemistry
  • Chromatography, High Pressure Liquid
  • Gene Expression Regulation, Plant
  • Molecular Sequence Data
  • Peptides / analysis
  • Peptides / genetics*
  • Peptides / metabolism*
  • Plant Proteins / isolation & purification*
  • Plant Proteins / metabolism
  • Plant Roots / genetics
  • Plant Roots / metabolism
  • Plant Shoots / metabolism
  • Plants, Genetically Modified
  • Polymerase Chain Reaction / methods
  • Protein Transport
  • RNA Processing, Post-Transcriptional
  • Sequence Analysis, RNA
  • Soybeans / metabolism*
  • Xylem / metabolism*

Substances

  • Chlorophenols
  • Peptides
  • Plant Proteins
  • 2-chlorophenol