Abstract
Calcium regulates diverse physiological functions in organisms. Influx of Ca2+ is evoked by internal or external stimulus. Alterations of cytoplasmic Ca2+ concentration due to Ca2+ influx are detected by calcium-binding proteins, ex. calmodulin, calcium dependent protein kinases, which convert Ca2+ signals into cellular events.
To analyze Ca2+ kinetics in plant cell, we established Ca imaging system in Lotus japonicus. In the root hair cells of leguminous plants, Calcium spiking, a periodical increase of Ca2+ concentration, is induced by perception of infection signals released from symbiotic partners.Our system clearly detected the symbiotic Ca spiking in response to root nodule symbiosis signal, Nod factor. In addition, another type of Ca oscillation was detected during elongation of the root hair cells. This 'non-symbiotic' Ca oscillation had different wave profile from that of the symbiotic Ca spiking, suggesting that different Ca signatures trigger different cellular events in the root hair cells.
