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Sep. 8, 2006 Research Highlight Biology

Naturally occurring peptides suppress plant development

Interdisciplinary research demonstrates how peptides control plant stem cell development

Image of Zinnia plant Figure 1: The plant Zinnia elegans.

A team of Japanese plant biologists and biochemists has identified a naturally occurring peptide that suppresses development of critical vascular structures in plants.

As in animals, development of plants includes early ‘body patterning’ and differentiation of primitive stem cells into specialized cells, such as the vascular structures for transporting water and nutrients.

Reporting in Science 1, the team led by the University of Tokyo’s Hiroo Fukuda, studied the development of the main conductive structures in plants required for water transport—the so-called ‘tracheary elements’.

Studying cells from the plant Zinnia elegans (Fig. 1) and a process called trans-differentiation, in which specialized photosynthetic cells become specialized tracheary elements, the team found an inhibitor of tracheary element formation. They called the inhibitor the ‘tracheary element differentiation inhibitory factor’ (TDIF). Preliminary studies indicated TDIF was a protein, but its molecular nature was not immediately clear.

Biochemical analyses by Naoshi Dohmae from the RIKEN Discovery Research Institute in Wako identified TDIF as a 12 amino acid peptide. “We fractionated TDIF from plant materials in a filtered culture medium using a combination of high performance liquid chromatography techniques (ion exchange, gel filtration, reversed-phase),” explains Dohmae. “Finally we isolated TDIF using reversed-phase high performance liquid chromatography. We then determined the TDIF sequence by tandem mass spectrometry and standard peptide sequencing.”

Dohmae’s work enabled TDIF to be identified as a member of the CLE family of peptides. All plants encode approximately 26 small peptides referred to as ‘CLV3/ESR-related’ or ‘CLE’ peptides that have conserved amino acid sequences. Previous studies have shown that CLE peptides likely provide essential cues for normal plant development.

Using the sequence data provided by Dohmae’s team, Fukuda’s team searched protein databases for homologies to TDIF and found matches with the CLE peptides from the plant Arabidopsis thalania.

The CLE peptides of Arabidoposis are grouped into several clades, or groups, based on sequence homology. Tests on all 26 Arabidoposis CLE peptides of 12 amino acids (dodecapeptides) for TDIF activity by Fukuda and colleagues demonstrated two counteracting activities, one that promotes stem cell differentiation, such as the CLE3 peptide of Arabidoposis, and one that inhibits stem cell differentiation, such as TDIF, during vascular development.

This work demonstrates that naturally expressed peptides provide two key opposing functions during plant stem cell differentiation.

Dohmae’s biomedical analyses, crucial for identifying the biochemical nature of TDIF, demonstrate the importance of basic biomolecular characterization techniques in scientific advances.

References

  • 1. Ito, Y., Nakanomyo, I., Motose, H., Iwamoto, K., Sawa, S., Dohmae, N., & Fukuda, H. Dodeca-CLE peptides as suppressors of plant stem cell differentiation. Science 313, 842–845 (2006). doi: 10.1126/science.1128436

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