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Regulation of Arabidopsis defense responses against Spodoptera littoralis by CPK-mediated calcium signaling

BACKGROUND: Plant Ca(2+ )signals are involved in a wide array of intracellular signaling pathways after pest invasion. Ca(2+)-binding sensory proteins such as Ca(2+)-dependent protein kinases (CPKs) have been predicted to mediate the signaling following Ca(2+ )influx after insect herbivory. However,...

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Detalles Bibliográficos
Autores principales: Kanchiswamy, Chidananda Nagamangala, Takahashi, Hirotaka, Quadro, Stefano, Maffei, Massimo E, Bossi, Simone, Bertea, Cinzia, Zebelo, Simon Atsbaha, Muroi, Atsushi, Ishihama, Nobuaki, Yoshioka, Hirofumi, Boland, Wilhelm, Takabayashi, Junji, Endo, Yaeta, Sawasaki, Tatsuya, Arimura, Gen-ichiro
Formato: Texto
Lenguaje:English
Publicado: BioMed Central 2010
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3095362/
https://www.ncbi.nlm.nih.gov/pubmed/20504319
http://dx.doi.org/10.1186/1471-2229-10-97
Descripción
Sumario:BACKGROUND: Plant Ca(2+ )signals are involved in a wide array of intracellular signaling pathways after pest invasion. Ca(2+)-binding sensory proteins such as Ca(2+)-dependent protein kinases (CPKs) have been predicted to mediate the signaling following Ca(2+ )influx after insect herbivory. However, until now this prediction was not testable. RESULTS: To investigate the roles CPKs play in a herbivore response-signaling pathway, we screened the characteristics of Arabidopsis CPK mutants damaged by a feeding generalist herbivore, Spodoptera littoralis. Following insect attack, the cpk3 and cpk13 mutants showed lower transcript levels of plant defensin gene PDF1.2 compared to wild-type plants. The CPK cascade was not directly linked to the herbivory-induced signaling pathways that were mediated by defense-related phytohormones such as jasmonic acid and ethylene. CPK3 was also suggested to be involved in a negative feedback regulation of the cytosolic Ca(2+ )levels after herbivory and wounding damage. In vitro kinase assays of CPK3 protein with a suite of substrates demonstrated that the protein phosphorylates transcription factors (including ERF1, HsfB2a and CZF1/ZFAR1) in the presence of Ca(2+). CPK13 strongly phosphorylated only HsfB2a, irrespective of the presence of Ca(2+). Furthermore, in vivo agroinfiltration assays showed that CPK3-or CPK13-derived phosphorylation of a heat shock factor (HsfB2a) promotes PDF1.2 transcriptional activation in the defense response. CONCLUSIONS: These results reveal the involvement of two Arabidopsis CPKs (CPK3 and CPK13) in the herbivory-induced signaling network via HsfB2a-mediated regulation of the defense-related transcriptional machinery. This cascade is not involved in the phytohormone-related signaling pathways, but rather directly impacts transcription factors for defense responses.