Plant peptides – taking them to the next level
Overview of peptide signalling and activity. Photo: Barbara de Coninck and Ive de Smet
By Jonathan Ingram, Journal of Experimental Botany
The recent Special Issue from Journal of Experimental Botany – Plant peptides – taking them to the next level – comes in response to the particularly fast-moving pace of discovery in peptide signalling. Together with Peptides take centre stage in plant signalling, in 2015, there is truly comprehensive coverage, with the characteristic focused reviews and latest research findings. Small signalling peptides discussed include CLAVATA3/EMBRYO SURROUNDING REGION (CLE), C-TERMINALLY ENCODED PEPTIDE (CEP), RAPID ALKALINIZATION FACTOR (RALF) and ROOT GROWTH FACTOR/CLE-LIKE/GOLVEN (RGF/ CLEL/GLV).
Barbara de Coninck and Ive de Smet provide a handy introduction and overview, guiding the non-specialist. Key points in peptide signalling and activity are highlighted, moving from inactive precursor proteins through processing and further interaction with a receptor complex; and the broad categories – cysteine-rich peptides and post-translationally modified peptides – are also described. As well as putting the different contributions in the issue into their wider context, they go on to detail current blocks to progress, such as tools for visualizing peptides and peptide–receptor interactions in planta, and speculate about what discoveries might come next – including processing steps and the enzymes involved, and further components downstream of peptide–receptor interactions.
Writing in the eXtra Botany section of the journal, Michael Taleski and colleagues comment on one of the stand-out contributions in the issue, dealing with C-TERMINALLY ENCODED PEPTIDE (CEP) in the control of lateral root growth and development (Roberts et al.). The authors show that auxin negatively regulates CEP5 expression in Arabidopsis, and suggest that CEP5 may act locally in lateral root initiation. They also provide a comparison with the earlier work by Tabata et al. in Science. These authors identified two CEP receptors and evidenced the involvement of long-distance CEP movement in N-demand signalling. Taleski et al. suggest that inconsistency may simply reflect the incomplete nature of the story, and point to the likely complexity (and context-dependency) involved.
State of the field
De Coninck and De Smet note that ‘functional roles of signalling peptides are increasingly understood in roots, a model organ that lends itself to developmental study because of its simple cellular organization and easy growth in non-soil media, which facilitates phenotypic analyses. Although an increasing number of reports indicate that signalling peptides are involved in every aspect of a plant’s life cycle, functional studies are often hampered by the lack of suitable knock-out lines.’
They are also upbeat about progress on peptide–receptor interactions: ‘We are … moving from a handful, largely identified through genetic studies, to several pairs, identified through a wide range of approaches. Very recently, LRR-RLKs have also been identified for RGF/CLEL/GLV peptides … Given the new tools and approaches available, we expect that the number of known peptide–receptor pairs will quickly increase.
Journal of Experimental Botany publishes extensively on peptide signalling. Browse and search on the homepage.
Workshops on peptide signalling in plants
The 3rd European Workshop on Peptide Signalling and Activity in Plants took place in Ghent (Belgium) in 2015, covering peptides in development, peptides and interactions with other organisms, peptide–receptor interactions and peptide downstream signalling. This Special Issue was inspired by that meeting, for which Journal of Experimental Botany was one of a number of sponsors. See also Plant Peptides & Receptors 2016.
Journal of Experimental Botany publishes an exciting mix of research, review and comment on fundamental questions of broad interest in plant science. Regular special issues highlight key areas.
Author: Jonathan Ingram
Category: Journal of Experimental Botany