COMPARISON OF SPHAEROPSIS-SAPINEA AND SPHAEROPSIS-SAPINEA F SP CUPRESSI

Seven isolates of Sphaeropsis sapinea, and three of a fungus reported to represent a physiological form of S. sapinea, i.e. S. sapinea f. sp . cupressi, were compared on the basis of various morphological and cu ltural criteria. All isolates lacked conidiophores and conidia were ge nerally produced through holoblastic ontogeny and percurrent prolifera tion. Conidial lengths of S. sapinea were significantly (P = 0.001) lo nger than those of S. sapinea f. sp. cupressi but widths did not diffe r significantly. All isolates of S. sapinea grew significantly faster (P = 0.01) than any single isolate of S. sapinea f. sp. cupressi on 5 of 6 culture media and at 10, 20, 25 and 30 degrees C. Sphaeropsis sap inea, S. sapinea f. sp. cupressi and three closely related taxa, namel y Lasiodiplodia theobromae, Diplodia mutila, and Botryosphaeria dothid ea were compared using isozyme analysis. Of the 16 alleles that occurr ed in S. sapinea f. sp. cupressi, 3 were unique to this taxon. With th e exception of Amy (160) and Gpi (107), which occurred only in S. sapi nea and S. sapinea f. sp. cupressi, 11 other alleles common to these t wo taxa were also common with 1, or more, of the remaining 3 taxa. Clu ster analysis of the genetic distances between the five taxa revealed that S. sapinea was more closely related to D. mutila than to S. sapin ea f. sp. cupressi, The results of this study, therefore, provide subs tantial evidence for the lack of a close relationship between S. sapin ea f. sp. cupressi and S. sapinea.