Ficus carica (2n=26) is one of the oldest fruit trees of the Mediterranean basin. In the last years there has been an increasing interest in this species in particular for questions related to germplasm such as genetic diversity and cultivar identification. This study was undertaken to gain more knowledge on F. carica cytogenetics and provide data useful for the characterization of its germplasm. Karyomorphological analysis and physical mapping of 18S-25S and 5S rDNA by the FISH technique contributed to defining the basic traits of the chromosome complement of F. carica. However the most interesting result was the discovery of triploid (2n=39) cytotypes of the cultivated common fig. This result demonstrates the importance of cytogenetic investigations in studies on fig germplasm and emphasizes the role of cross fertilization as source of variability not only in wild populations but also in cultivated forms. In fact there is no doubt that the triploid cytotypes have a sexual origin. The results of the pollen analysis suggest spontaneous sexual polyploidization as a possible origin of triploid cytotypes. Further studies are necessary to clarify, along with its origin, the effective spreading of polyploidy, the presence of other ploidy levels and their distribution in wild and cultivated forms.
Presence of triploid cytotypes in the common fig (Ficus carica L.)
FALISTOCCO, Egizia
2009
Abstract
Ficus carica (2n=26) is one of the oldest fruit trees of the Mediterranean basin. In the last years there has been an increasing interest in this species in particular for questions related to germplasm such as genetic diversity and cultivar identification. This study was undertaken to gain more knowledge on F. carica cytogenetics and provide data useful for the characterization of its germplasm. Karyomorphological analysis and physical mapping of 18S-25S and 5S rDNA by the FISH technique contributed to defining the basic traits of the chromosome complement of F. carica. However the most interesting result was the discovery of triploid (2n=39) cytotypes of the cultivated common fig. This result demonstrates the importance of cytogenetic investigations in studies on fig germplasm and emphasizes the role of cross fertilization as source of variability not only in wild populations but also in cultivated forms. In fact there is no doubt that the triploid cytotypes have a sexual origin. The results of the pollen analysis suggest spontaneous sexual polyploidization as a possible origin of triploid cytotypes. Further studies are necessary to clarify, along with its origin, the effective spreading of polyploidy, the presence of other ploidy levels and their distribution in wild and cultivated forms.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
