ISOLATION OF TRIPLOID AND TETRAPLOID OLIVE (OLEA-EUROPAEA L) PLANTS FROM MIXOPLOID CV FRANTOIO AND LECCINO MUTANTS BY IN-VIVO AND IN-VITRO SELECTION

This paper reports a procedure for isolating triploid and tetraploid o live plants, which have not been produced before either artificially o r in nature. These polyploids were isolated from two mixoploid somatic mutants obtained earlier by treating 'Frantoio' and 'Leccino' plantle ts with gamma radiation. The mixoploid mutants exhibit increased thick ness of leaf stem and root tissues, short internodes, a modified leaf lamina shape and a strong resistance to Spilocaea oleagina (Cast.) Hug h. In addition, they produce a mixture of normal drupes and some abnor mally large ones, almost twice normal size. The variation in the nucle ar DNA content of the mixoploid mutants is closely correlated with var iation in their pollen size, crop capacity and the production of large fruit. Triploid genotypes with 69 chromosomes were isolated by germin ating the seeds of these large fruits, collected from both the mixoplo id mutants. Tetraploid plantlets, with 92 chromosomes, were obtained f rom cv. 'Frantoio' by selecting in vitro, during several proliferation phases, the shoots with obvate leaf shape which occurred among the sh oots with normal lanceolate or intermediate leaf shape.