The Root-Knot Nematode Calreticulin Mi-CRT Is a Key Effector in Plant Defense Suppression

• Published in: Molecular plant-microbe interactions Vol. 26; no. 1; pp. 97 - 105
• Main Authors: JAOUANNET, M, MAGLIANO, M, ARGUEL, M. J, GOURGUES, M, EVANGELISTI, E, ABAD, P, ROSSO, M. N
• Format: Journal Article
• Language: English
• Published: St. Paul, MN APS Press 2013; American Phytopathological Society; The American Phytopathological Society
• Subjects: Animals; Arabidopsis - genetics; Arabidopsis - immunology; Arabidopsis - parasitology; Arabidopsis - physiology; Arabidopsis thaliana; Biological and medical sciences; Calreticulin; Calreticulin - genetics; Calreticulin - metabolism; Differentiation; Disease Susceptibility; Feeding; Female; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Profiling; Gene Expression Regulation, Plant - genetics; Gene Knockdown Techniques; Helminth Proteins - genetics; Helminth Proteins - metabolism; Host-Parasite Interactions; Infection; Life Sciences; Nematoda; Nicotiana - parasitology; Oomycetes; Parasite Egg Count; Parasites; Pathogens; Phytopathology and phytopharmacy; Phytopathology. Animal pests. Plant and forest protection; Phytophthora - pathogenicity; Phytophthora parasitica; Plant Diseases - parasitology; Plant Leaves - genetics; Plant Leaves - parasitology; Plant Leaves - physiology; RNA Interference; RNA, Plant - genetics; RNA-mediated interference; Roots; Seedlings - genetics; Seedlings - parasitology; Seedlings - physiology; Sequence Deletion; Solanum lycopersicum - parasitology; Tylenchoidea - pathogenicity; Tylenchoidea - physiology; Vegetal Biology; Virulence; Binding protein; Calreticulin; Plant; Root; Suppression
• ISSN: 0894-0282; 1943-7706
• DOI: 10.1094/mpmi-05-12-0130-r

Root-knot nematodes (RKN) are obligate biotrophic parasites that settle close to the vascular tissues in roots, where they induce the differentiation of specialized feeding cells and maintain a compatible interaction for 3 to 8 weeks. Transcriptome analyses of the plant response to parasitic infection have shown that plant defenses are strictly controlled during the interaction. This suggests that, similar to other pathogens, RKN secrete effectors that suppress host defenses. We show here that Mi-CRT, a calreticulin (CRT) secreted by the nematode into the apoplasm of infected tissues, plays an important role in infection success, because Mi-CRT knockdown by RNA interference affected the ability of the nematodes to infect plants. Stably transformed Arabidopsis thaliana plants producing the secreted form of Mi-CRT were more susceptible to nematode infection than wild-type plants. They were also more susceptible to infection with another root pathogen, the oomycete Phytophthora parasitica. Mi-CRT overexpression in A. thaliana suppressed the induction of defense marker genes and callose deposition after treatment with the pathogen-associated molecular pattern elf18. Our results show that Mi-CRT secreted in the apoplasm by the nematode has a role in the suppression of plant basal defenses during the interaction.