2026-04-10 ジョージア大学（UGA）
This collage shows fluorescing feeding tubes — specialized structures formed by plant-parasitic root-knot nematodes inside enlarged root cells — to help them efficiently draw nutrients from their host. (Photo by Melissa Mitchum and Richard Hussey)
＜関連情報＞
- https://fieldreport.caes.uga.edu/news/secret-of-root-knot-nematodes-lifeline/
- https://www.pnas.org/doi/10.1073/pnas.2520476123
- https://link.springer.com/article/10.1007/BF02562553
ネコブセンチュウの摂食管の主要構成要素として、口針から分泌されるエフェクタータンパク質ファミリーを同定 Identification of a stylet-secreted effector protein family as a core component of root-knot nematode feeding tubes
Richard S. Hussey, Melissa G. Mitchum, Rebekah L. Paul, +2 , and Lesa J. Beamer
Proceedings of the National Academy of Sciences Published:February 3, 2026
DOI:https://doi.org/10.1073/pnas.2520476123
Significance
Root-knot nematodes represent the most damaging group of plant-parasitic nematodes impacting global crop production. These obligate, sedentary endoparasites produce an essential structure, called a feeding tube, inside the giant feeding cells they induce in host roots to take up nutrients required to complete their life cycle. The feeding tube remains one of the best described, yet the least understood feature of sedentary endoparasitism. We developed a protocol to isolate feeding tubes for proteome analysis and identified a stylet-secreted effector protein family as a core component of feeding tubes that promises to shed light on their structure and function in nematode parasitism of plants.
Abstract
Proteins secreted from a mouth stylet of sedentary plant-parasitic root-knot nematodes self-polymerize to form a unique feeding tube structure within host cells modified into giant feeding cells by the nematode. Feeding tubes have essential functions as they complex with the host endomembrane system for nutrient uptake to sustain parasitism. Despite their significance, they remain one of the least understood aspects of nematode parasitism of plants. Their small size and location within giant-cells deeply embedded within galls encasing adult females has prohibited studies to isolate and discern their molecular composition. Here, we developed a protocol for the isolation and semipurification of root-knot nematode feeding tubes from giant-cell cytoplasm of several host plant species to provide a unique view of these structures at the light and scanning electron microscopy level revealing previously undescribed features of their structure. Our methods allowed for the isolation and solubilization of sufficient quantities of enriched feeding tubes enabling a comparative proteome analysis across host species that identified proteins with an increased likelihood to function in feeding tube formation. A comparison across root-knot nematode species further narrowed candidates to a conserved class of secretory proteins that specifically localized within secretory granules of the dorsal gland of adult females and in feeding tubes formed within host cell cytoplasm to unequivocally demonstrate these proteins as core components of feeding tubes. Our finding gives scientists a look into the protein composition of feeding tubes opening the door to a better understanding of their structure and function in nematode parasitism.
ネコブセンチュウMeloidogyne incognitaによって植物に誘導された巨大細胞内に形成された摂食管の超微細構造 Ultrastructure of feeding tubes formed in giant-cells induced in plants by the root-knot nematodeMeloidogyne incognita
R. S. Hussey & C. W. Mims
Protoplasma Published:June 1991
DOI:https://doi.org/10.1007/BF02562553
Summary
The plant pathogenic nematodeMeloidogyne incognita forms conspicuous tubular structures referred to as feeding tubes in special food cells, called giant-cells, induced and maintained in susceptible host roots by feeding nematodes. Feeding tubes are formed by nematode secretions injected into giant-cells via a stylet and apparently function to facilitate withdrawal of soluble assimilates by the parasite. In giant-cells in roots of the four host species examined in this study, feeding tube morphology was identical. Tubes were straight to slightly curved structures just less than 1 μm wide and up to slightly more than 70 μm long. At the ultrastructural level, each tube consisted of a 190–290 nm thick, electron-dense, crystalline wall surrounding an electron-transparent lumen with a diameter of 340–510 nm. The distal end of the tube was sealed with wall material. Older tubes were found free in the host cytoplasm while the proximal ends of young tubes were attached to the host cell wall via short wall ingrowths through which the nematode’s stylet was inserted. An elaborate membrane system was associated with the feeding tubes and was most extensive around newly formed tubes. Contiguous to the feeding tube wall, this membrane system consisted of strands of smooth endoplasmic reticulum while rough endoplasmic reticulum predominated toward the outer margin of the membrane system. Vacuoles and mitochondria were excluded from a zone of cytoplasm surrounding feeding tubes. This zone of exclusion, as well as the membrane system noted above, tended to be less pronounced or absent around older tubes no longer being used by the nematode.
