Studies on Calcium Release and H2O2 Level Produced by the Elicitor Induced Plant Cell by Fluorescence Probing

Using fluorescence probing technology, we studied the mechanism and interrelations of calcium release and H₂O₂ production in situ in living tissues of tobacco and cotton plants which were induced by pathogen elicitor, salicylic acid (SA) and pectinase respectively. Results showed that (1) pathogen elicitors could induced H₂O₂ response in epidermis cells regardless of environmental calcium, but in mesophyll protoplast, H₂O₂ response could only be induced at calcium condition. Similarly, SA and pectinase induced H₂O₂ response could only be observed at calcium condition; (2) pathogen elicitors could induce calcium response in both epidermis cells and protoplasts regardless of environmental calcium, while calcium response couldn’t be induced at non-calcium condition by SA and pectinase; (3) H₂O₂ response and calcium response in protoplast were faster than that in the whole cell. These results indicated that pathogen elicitors can induce the release of cell wall calcium and the cell wall calcium release is independent to pectinase. And it is concluded that free calcium influx is necessary for the oxidative burst and cell wall calcium has an irreplaceable role in defense signal transduction.