| dc.description.abstract |
Application of Nod factors to growing, responsive root hairs of the bean Phaseolus vulgaris induces marked changes in both the intracellular cytosolic free calcium (Ca2+) and in the influx of extracellular [Ca2+]. The intracellular [Ca2+], which has been measured by ratiometric imaging in cells microinjected with fura-2-dextran (70 kDa), elevates within 5 min from approximately 400 nM to 1500 nM in localised zones in the root hair apex. Of particular note is the observation that the elevated regions of [Ca2+] appear to shift position during short time intervals. Increases in and fluctuations of the intracellular [Ca2+] are also observed in the perinuclear region after 10-15 min treatment with Nod factors. The extracellular Ca2+ flux, detected with the non-invasive, calcium specific vibrating electrode, is inwardly directed and also increases quickly in response to Nod factors from 13 pmol cm(-2) s(-1) to 28 pmol cm(-2) s(-1). Chitin-oligomers, which are structurally similar but biologically inactive when compared to the active Nod factors, fail to elicit changes in either intracellular or extracellular Ca2+. The similar timing and location of the intracellular elevations and the increased extracellular influx provide support for the idea that Ca2+ participates in secretion and cell wall remodelling, which occur in anticipation of root hair deformation and curling. |
en_US |