|DAVIES, LAURA - Washington State University|
|Brown, Charles - Chuck|
|ELLING, AXEL - Washington State University|
Submitted to: Plant Cell Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/7/2014
Publication Date: 1/1/2015
Citation: Davies, L., Brown, C.R., Elling, A. 2015. Calcium is involved in the RMc1(blb)-mediated hypersensitive response against Meloidogyne chitwoodi in potato. Plant Cell Reports. 34:167-177.
Interpretive Summary: When a suceptible potato olant meets a virulent Columbia root-knot nematode, the plant treats the nematode as an honored guest offering it speciall acomodations for the rest of its life and permission to raise two hundred offspring. However, a resistant potato is extremely impolite, slamming the door, so to speak, and starting a series of chemical warfare attacks against the nematode. This is what this study elucidated in the case of this host and its pest. One of the things that happpens with a unouccessful parasitism is there is a burst of synthesis of reactive oxidative species, and oxidative reactions. This is accompanied by the death of plant root cells in the proximity of the nemstode, visible as a browning reaction This study showed that resistant potato recognizes Coumbia root-knot nematode and turns on enzymes which channel calcium ions to the site where a strong oxidative reaction is in full force by 24 hoursafter the nematode enters the root. The visible aspect of this reaction is the accumulation of brown coloration around the nematode, cessation of nematode movement and failure of the nematode to progress in further development. In this world the unwelcome guest is killed and bricked away in her chamber. Our undertanding of components of resistance reactions will help to make them stronger to achieve bigger reductions of damage in crop plants
Technical Abstract: The resistance (R) gene RMc1(blb) confers resistance against the plant-parasitic nematode, Meloidogyne chitwoodi. Avirulent and virulent nematodes were used to functionally characterize the RMc1(blb)-mediated resistance mechanism in potato (Solanum tuberosum). Histological observations indicated a hypersensitive response (HR) occurred during avirulent nematode infection. This was confirmed by quantifying reactive oxygen species activity in response to avirulent and virulent M. chitwoodi. To gain an insight into the signal transduction pathways mediating the RMc1(blb)-induced HR, chemical inhibitors were utilized. Inhibiting Ca2+ channels caused a significant reduction in electrolyte leakage, an indicator of cell death. Labeling with a Ca2+-sensitive dye revealed high Ca2+ levels in the root cells surrounding avirulentnematodes. Furthermore, the calcium-dependent protein kinase (CDPK), StCDPK4had a higher transcript level in RMc1(blb) potato roots infected with avirulent nematodes in comparison to roots infected with virulent M. chitwoodi. The results ofthis study indicate Ca2+ plays a role in the RMc1(blb)-mediated resistance against M. chitwoodi in potato.