Plant-parasitic nematodes use paired nuclear receptors to switch from invasion to feeding mode
Researchers have identified a transcription factor called DGR-1 in the beet cyst nematode Heterodera schachtii that acts as a master regulator, switching off early invasion-related proteins and switching on later proteins needed to establish a feeding site inside the plant. DGR-1 works in opposition to a previously known regulator, SUGR-1, and together the two control nearly half of all early-stage effector proteins the nematode uses to manipulate its host. Disrupting DGR-1 slows nematode development in Arabidopsis and mustard plants, suggesting that targeting effector regulation could be a viable crop protection strategy.
A study posted to bioRxiv describes the discovery of DGR-1 (Dorsal Gland Regulator-1), a nuclear hormone receptor in the beet cyst nematode Heterodera schachtii that coordinates a timed shift in the nematode's infection strategy. Early in infection, the nematode uses lytic effectors to break through plant cell walls and migrate toward the vascular cylinder; DGR-1 represses these early effectors while activating a later suite of biotrophic effectors that help the nematode establish a permanent feeding structure. DGR-1 acts antagonistically with SUGR-1, the only other known transcriptional regulator of effectors in plant-parasitic nematodes, and together the pair governs expression of roughly half of all early-stage effectors and more than one-fifth of all effectors identified in H. schachtii. The researchers also found that chemical signals leaking from roots of Arabidopsis mutants lacking a functional Casparian strip — a barrier that normally confines certain molecules to the vascular cylinder — specifically upregulate dgr-1 but not sugr-1, suggesting the nematode reads compartment-specific host cues to time its effector switch. When DGR-1 was experimentally misregulated, nematode development was delayed in both Arabidopsis and mustard, two agriculturally relevant host plants. The authors propose that strategies aimed at disrupting effector regulation, rather than individual effectors, could offer broader and more durable protection against cyst nematodes, which cause significant crop losses worldwide.
What's missing
As a preprint, this study has not yet undergone formal peer review, so findings should be treated as preliminary. The study does not report field or agronomic trials, leaving open how effectively targeting DGR-1 or effector regulation could be translated into practical crop protection. The precise molecular mechanism by which DGR-1 and SUGR-1 antagonize each other, and the identity of the specific vascular-cylinder-derived signals that activate dgr-1, remain uncharacterized. It is also unclear whether homologs of DGR-1 with similar regulatory roles exist in other economically important cyst nematode species such as Heterodera glycines or Globodera pallida.
What different sources said
- bioRxivCenter
Antagonistic action of a nuclear hormone receptor pair coordinates a switch from lytic to biotrophic effector production in a plant-parasitic nematode
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