In Planta Secretion of a Calreticulin by Migratory and Sedentary Stages of Root-Knot Nematode

Esophageal secretions from endoparasitic sedentary nematodes are thought to play key roles throughout plant parasitism, in particular during the invasion of the root tissue and the initiation and maintenance of the nematode feeding site (NFS) essential for nematode development. The secretion in planta of esophageal cell-wall-degrading enzymes by migratory juveniles has been shown, suggesting a role for these enzymes in the invasion phase. Nevertheless, the secretion of an esophageal gland protein into the NFS by nematode sedentary stages has never been demonstrated. The calreticulin Mi-CRT is a protein synthesized in the esophageal glands of the root-knot nematode Meloidogyne incognita. After three-dimensional modeling of the Mi-CRT protein, a surface peptide was selected to raise specific antibodies. In planta immunolocalization showed that Mi-CRT is secreted by migratory and sedentary stage nematodes, suggesting a role for Mi-CRT throughout parasitism. During the maintenance of the NFS, the secreted Mi-CRT was localized outside the nematode at the tip of the stylet. In addition, Mi-CRT accumulation was observed along the cell wall of the giant cells that compose the feeding site, providing evidence for a nematode esophageal protein secretion into the NFS.

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PUCHI Regulates Giant Cell Morphology During Root-Knot Nematode Infection in Arabidopsis thaliana

Frontiers in Plant Science ◽

10.3389/fpls.2021.755610 ◽

2021 ◽

Vol 12 ◽

Author(s):

Reira Suzuki ◽

Mizuki Yamada ◽

Takumi Higaki ◽

Mitsuhiro Aida ◽

Minoru Kubo ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Cell Wall ◽

Genetic Regulation ◽

Three Dimensional ◽

Acid Synthesis ◽

Giant Cells ◽

Loss Of Function ◽

Wild Type ◽

Root Knot Nematode ◽

In The Wild

Parasitic root-knot nematodes transform the host’s vascular cells into permanent feeding giant cells (GCs) to withdraw nutrients from the host plants. GCs are multinucleated metabolically active cells with distinctive cell wall structures; however, the genetic regulation of GC formation is largely unknown. In this study, the functions of the Arabidopsis thaliana transcription factor PUCHI during GC development were investigated. PUCHI expression was shown to be induced in early developing galls, suggesting the importance of the PUCHI gene in gall formation. Despite the puchi mutant not differing significantly from the wild type in nematode invasion and reproduction rates, puchi GC cell walls appeared to be thicker and lobate when compared to the wild type, while the cell membrane sometimes formed invaginations. In three-dimensional (3D) reconstructions of puchi GCs, they appeared to be more irregularly shaped than those in the wild type, with noticeable cell-surface protrusions and folds. Interestingly, the loss-of-function mutant of 3-KETOACYL-COA SYNTHASE 1 showed GC morphology and cell wall defects similar to those of the puchi mutant, suggesting that PUCHI may regulate GC development via very long chain fatty acid synthesis.

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Cell Wall Modifications in Giant Cells Induced by the Plant Parasitic Nematode Meloidogyne incognita in Wild-Type (Col-0) and the fra2 Arabidopsis thaliana Katanin Mutant

International Journal of Molecular Sciences ◽

10.3390/ijms20215465 ◽

2019 ◽

Vol 20 (21) ◽

pp. 5465 ◽

Cited By ~ 3

Author(s):

Christianna Meidani ◽

Nikoletta G. Ntalli ◽

Eleni Giannoutsou ◽

Ioannis-Dimosthenis S. Adamakis

Keyword(s):

Cell Wall ◽

Meloidogyne Incognita ◽

Cell Walls ◽

Giant Cells ◽

Wild Type ◽

Root Knot Nematode ◽

Cell Wall Polysaccharides ◽

Developmental Defects ◽

Feeding Site

Meloidogyne incognita is a root knot nematode (RKN) species which is among the most notoriously unmanageable crop pests with a wide host range. It inhabits plants and induces unique feeding site structures within host roots, known as giant cells (GCs). The cell walls of the GCs undergo the process of both thickening and loosening to allow expansion and finally support nutrient uptake by the nematode. In this study, a comparative in situ analysis of cell wall polysaccharides in the GCs of wild-type Col-0 and the microtubule-defective fra2 katanin mutant, both infected with M. incognita has been carried out. The fra2 mutant had an increased infection rate. Moreover, fra2 roots exhibited a differential pectin and hemicellulose distribution when compared to Col-0 probably mirroring the fra2 root developmental defects. Features of fra2 GC walls include the presence of high-esterified pectic homogalacturonan and pectic arabinan, possibly to compensate for the reduced levels of callose, which was omnipresent in GCs of Col-0. Katanin severing of microtubules seems important in plant defense against M. incognita, with the nematode, however, to be nonchalant about this “katanin deficiency” and eventually induce the necessary GC cell wall modifications to establish a feeding site.

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