Studio sulla diversità di ecotipi di Prunus webbii diffusi in Puglia

Prunus webbii, a wild species related to cultivated almond (Prunus amygdalus), grows spontaneously in marginal areas of mediterranean countries. It is considered a valuable genetic resources not only for im-proving self incompatibility in almond but also as rootstock for drought environments. The objective of this work is to study the diversity, by isozyme markers and multivariate analysis (Cluster), of a population of Prunus webbii. Fruit (80-100) were collected from each of different ecotypes which were identified in marginal areas of Apulia (South Italy). From ger¬minated seeds of each ecotype, 20 random seedlings were re-tained for leaf isozyme analysis (GOT, LAP, ME, G6PDH, MDH, PGM, PGI, SKDH). The genetic relationships among ecotypes were estimated from Rogers distance equation based on electrophoretic band frequency. A cluster analysis (UPG-MA) were applied on these data. Our results reveal that some isozymes systems were poly¬morphic such as GOT and PGM with two zones of activity (Got-1, Got-2, Pgm-1, Pgm-2) each with 3 electrophoretic patterns and Lap-1, G6pdh-l, G6pdh-2, Me-1, Me-2 with two patterns as it is shown in tab.2; other isozymes (MDH and SKDH) were tnonomorphic. Genetic distances based on the electrophoretic banding patterns and Rogers equation were used for cluster analysis to differentiate the Prunus webbii ecotypes under consideration. The dendrogram of fig. 2 doesn't reveal the formation of large and distint groups but the tendency to aggregate ecotypes in few and small groups not only in relation to isozyme pattern but also in relation to the nut size. The gradual distribution of these ecotypes in relation to nut size might be interpreted as representing a variation bet¬ween Prunus webbii (with small nuts) and Prunus amygdalus (with large nuts). Further research is suggested to support pos¬sible hybridations between the two species and to explain the diversity among Prunus webbii ecotypes.