Despite myriad challenges, clinicians see room for progress.
Image credit: Shutterstock/David Tadevosian.
New Research In
Physical Sciences
Featured Portals
Articles by Topic
Biological Sciences
Featured Portals
Articles by Topic
Contributed by Frederick M. Ausubel, March 10, 2015 (sent for review May 10, 2014; reviewed by Michael G. Hahn and Jonathan D. G. Jones)
Significance
Damage-associated molecular patterns (DAMPs), released from host tissues as a consequence of pathogen attack, have been proposed as endogenous activators of immune responses in both animals and plants. Oligogalacturonides (OGs), oligomers of α-1,4–linked galacturonic acid generated in vitro by the partial hydrolysis of pectin, have been shown to function as potent elicitors of immunity when they are applied exogenously to plant tissues. However, there is no direct evidence that OGs can be produced in vivo or that they function as immune elicitors. This report provides the missing evidence that OGs can be generated in planta and can function as DAMPs in the activation of plant immunity.
Abstract
Oligogalacturonides (OGs) are fragments of pectin that activate plant innate immunity by functioning as damage-associated molecular patterns (DAMPs). We set out to test the hypothesis that OGs are generated in planta by partial inhibition of pathogen-encoded polygalacturonases (PGs). A gene encoding a fungal PG was fused with a gene encoding a plant polygalacturonase-inhibiting protein (PGIP) and expressed in transgenic Arabidopsis plants. We show that expression of the PGIP–PG chimera results in the in vivo production of OGs that can be detected by mass spectrometric analysis. Transgenic plants expressing the chimera under control of a pathogen-inducible promoter are more resistant to the phytopathogens Botrytis cinerea, Pectobacterium carotovorum, and Pseudomonas syringae. These data provide strong evidence for the hypothesis that OGs released in vivo act as a DAMP signal to trigger plant immunity and suggest that controlled release of these molecules upon infection may be a valuable tool to protect plants against infectious diseases. On the other hand, elevated levels of expression of the chimera cause the accumulation of salicylic acid, reduced growth, and eventually lead to plant death, consistent with the current notion that trade-off occurs between growth and defense.
Footnotes
- ↵1To whom correspondence may be addressed. Email: ausubel{at}molbio.mgh.harvard.edu or felice.cervone{at}uniroma1.it.
Author contributions: M.B., S.F., F.C., and G.D.L. designed research; M.B., D.P., S.R., Z.C., F.S., and S.F. performed research; M.B., D.P., S.R., Z.C., S.F., F.M.A., F.C., and G.D.L. analyzed data; M.B., D.P., S.F., F.M.A., F.C., and G.D.L. wrote the paper; and F.M.A., F.C., and G.D.L. supervised the project.
Reviewers: M.G.H., University of Georgia; and J.D.G.J., Sainsbury Laboratory.
The authors declare no conflict of interest.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1504154112/-/DCSupplemental.
Engineering DAMP release in Arabidopsis
Sign up for Article Alerts
Article Classifications
- Biological Sciences
- Plant Biology
Jump to section
You May Also be Interested in
Better explicating the strengths and shortcomings of these models will help refine projections and improve transparency in the years ahead.
Image credit: Witsawat.S.
Using CRISPR, researchers showed that a region some used to label “junk DNA” has a major role in a rare genetic disorder.
Image credit: Nathan Devery.
Mara Reed and Michael Manga explore why Yellowstone's Steamboat Geyser resumed erupting in 2018.
A study demonstrates how two enzymes—MHETase and PETase—work synergistically to depolymerize the plastic pollutant PET.
Image credit: Aaron McGeehan (artist).