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 molecular switch, turning off early invasion-related effectors and turning on later effectors needed to establish a feeding site inside the plant. DGR-1 works antagonistically with a previously known regulator, SUGR-1, and together the pair controls nearly half of all early-stage effectors and over a fifth of all effectors the nematode produces. The discovery suggests that disrupting effector regulation could be a viable strategy for protecting crops from these economically damaging pests.
Plant-parasitic nematodes like Heterodera schachtii cause significant agricultural damage by secreting waves of protein effectors that manipulate host plants at different stages of infection, but the molecular machinery coordinating these effectors has been poorly understood. The new study identifies DGR-1 (Dorsal Gland Regulator-1) as a dual-functional transcription factor that represses 'lytic' effectors used during initial plant invasion while simultaneously activating 'biotrophic' effectors needed to establish a long-term feeding relationship within the plant's vascular tissue. DGR-1 acts in opposition to SUGR-1 (Subventral Gland Regulator-1), the only other known effector transcription regulator in plant-parasitic nematodes, and together they govern expression of nearly half of all early-stage effectors. The researchers also found evidence that the nematode senses compartment-specific signals from the host plant: diffusates from Arabidopsis mutants with a defective Casparian strip — which normally restricts vascular molecules to the inner root — selectively upregulated dgr-1 but not sugr-1, suggesting the nematode detects where it is within the root and adjusts its effector program accordingly. Experimentally disrupting DGR-1 delayed nematode development in both Arabidopsis and mustard plants, providing proof-of-concept that targeting effector regulation could offer a new avenue for crop protection.
What's missing
The study is a preprint posted to bioRxiv and has not yet undergone formal peer review, so findings should be treated as preliminary. The paper does not report whether DGR-1 homologs exist in other economically important cyst or root-knot nematode species, which would be critical for assessing the broader applicability of any crop-protection strategies based on this target. The mechanism by which DGR-1 and SUGR-1 antagonize each other at the molecular level (e.g., direct protein interaction vs. competition for binding sites) is not fully resolved. Additionally, the study does not address whether the vascular-derived signals that upregulate dgr-1 have been chemically characterized.
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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