ABSTRACT

The alternative technique for collecting exudates from major parts of the plant employs a chelator, EDTA (King and Zeevaar, 1974). The procedure involves soaking petioles, for example, in a buffered solution containing EDTA, which prevents formation of callose (Fig. 14.1). This method is easily implemented and yields qualitative results (proportion of various amino acids transported) comparable to those obtained by the pure sap method (Weibull et ah, 1990). Indeed, it has also been shown that this method does not lead to significant contamination by adjacent xylem tissues (Urquhart and Joy, 1981; Rochat and Boutin, 1991).