Submitted to: Meeting Abstract
Publication Type: Abstract only
Publication Acceptance Date: 6/5/2005
Publication Date: 6/5/2005
Citation: Ivashuta, S., Liu, J., Liu, J., Lohar, D.P., Haridas, S., Bucciarelli, B., Vandenbosch, K.A., Vance, C.P., Harrison, M.J., Gantt, J.S. 2005. A calcium-dependent protein kinase controls root development and symbiotic interactions. 2005 Model Legume Congress, June 5-9, 2005, Pacific Grove, California. Paper No. S24, p. 35. Interpretive Summary:
Technical Abstract: It is well established that changes in cellular or sub-cellular Ca2+ concentrations are associated with both plant root hair development and the early steps of plant-microbe symbiotic interactions. However, the roles played by Ca2+ in these processes, the downstream signaling components and the relationships among developmental and symbiotic processes, remain largely unknown. Using a RNA interference (RNAi)-based screen for gene function in Medicago truncatula, we identified a putative Ca2+-dependent protein kinase (MtCDPK1) that is involved in both root development and symbiosis. Silencing MtCDPK1 in M. truncatula resulted in significantly reduced root hair and root lengths and diminution of both rhizobial and mycorrhizal symbiotic colonization. In addition to decreased root hair length, up to 60% of MtCDPK1 RNAi root hairs developed abnormally. These abnormalities, such as root hair tip swelling, growth redirection, and branching, resemble deformations that normally occur in competent root hairs in response to rhizobia or Nod-factor treatments. A MtCDPK1-promoter::GUS reporter construct introduced into M. truncatula roots indicated that MtCDPK1 is transcribed throughout the root with strongest expression in elongating root hairs and the root elongation zone. Additionally, microarray analysis revealed that silencing of MtCDPK1 led to perturbation of cell wall and defense-related gene expression. CM-H2DCF staining and confocal microscopy imaging demonstrated increased levels of reactive oxygen species (ROS) accumulation in MtCDPK1 RNAi roots as compared with control roots. We propose that MtCDPK1 is involved in the regulation of root cell development and is a mediator of symbiotic interactions in legumes.