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Plant Physiol

Title:		Argonaute 8 (AGO8) Mediates the Elicitation of Direct Defenses against Herbivory
Author(s):		Pradhan M; Pandey P; Gase K; Sharaff M; Singh RK; Sethi A; Baldwin IT; Pandey SP;
Address:		"Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, Nadia, West Bengal, India. Department of Molecular Ecology, Max Planck Institute for Chemical Ecology, 07745 Jena, Germany. National Institute of Biomedical Genomics, Kalyani, 741251 West Bengal, India. Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, Nadia, West Bengal, India sppandey@iiserkol.ac.in"
Journal Title:		Plant Physiol
Year:		2017
Volume:		20170815
Issue:		2
Page Number:		927 - 946
DOI:		10.1104/pp.17.00702
ISSN/ISBN:		1532-2548 (Electronic) 0032-0889 (Print) 0032-0889 (Linking)
Abstract:		"In Nicotiana attenuata, specific RNA-directed RNA polymerase (RdR1) and the Dicer-like (DCL3 and DCL4) proteins are recruited during herbivore attack to mediate the regulation of defense responses. However, the identity and role(s) of Argonautes (AGOs) involved in herbivory remain unknown. Of the 11 AGOs in the N. attenuata genome, we silenced the expression of 10. Plants silenced in NaAGO8 expression grew normally but were highly susceptible to herbivore attack. Larvae of Manduca sexta grew faster when consuming inverted-repeat stable transformants (irAGO8) plants but did not differ from the wild type when consuming plants silenced in AGO1 (a, b, and c), AGO2, AGO4 (a and b), AGO7, or AGO10 expression. irAGO8 plants were significantly compromised in herbivore-induced levels of defense metabolites such as nicotine, phenolamides, and diterpenoid glycosides. Time-course analyses revealed extensively altered microRNA profiles and the reduced accumulation of MYB8 transcripts and of the associated genes of the phenolamide and phenylpropanoid pathways as well as the nicotine biosynthetic pathway. A possible AGO8-modulated microRNA-messenger RNA target network was inferred. Furthermore, comparative analysis of domains revealed the diversity of AGO conformations, particularly in the small RNA-binding pocket, which may influence substrate recognition/binding and functional specificity. We infer that AGO8 plays a central role in the induction of direct defenses by modulating several regulatory nodes in the defense signaling network during herbivore response. Thus, our study identifies the effector AGO of the herbivore-induced small RNA machinery, which in N. attenuata now comprises RdR1, DCL3/4, and AGO8"
Keywords:		"Amino Acid Sequence Animals Argonaute Proteins/genetics/*metabolism Herbivory Larva Manduca/*physiology MicroRNAs/genetics *Models, Structural Phylogeny Plant Diseases/*immunology/parasitology Plant Proteins/genetics/*metabolism Plants, Genetically Modifi;"
Notes:		"MedlinePradhan, Maitree Pandey, Priyanka Gase, Klaus Sharaff, Murali Singh, Ravi K Sethi, Avinash Baldwin, Ian T Pandey, Shree P eng 2017/08/16 Plant Physiol. 2017 Oct; 175(2):927-946. doi: 10.1104/pp.17.00702. Epub 2017 Aug 15"