A NEW APPROACH TO OBTAIN POLYPLOID FORMS OF APPLE

To induce doubling of chromosome number in somatic tissues of apple cultivars ‘Florina’ and ‘Falstaff’ in vitro, oryzalin was added to shoot regeneration media.
In the range of concentrations from 0.5 μM to 1 μM, the frequency of shoot organogenesis from leaf explants was considerably reduced, suggesting that this range of oryzalin is optimal to induce tetraploidy in the cultivars tested.
A new cytological protocol using a cold pretreatment was developed to determine the chromosome number in cultured regenerants a few weeks after induction.
The chromosome number of the first putative tetraploid clone was confirmed to be 2n=68 from shoot tip squashes.
Induction of roots from stem internodes and shoots from leaf explants of this clone was considerably less efficient than the diploid ‘Florina’ under the same conditions.
If the problems of rooting can be overcome, tetraploid forms of apple cultivars produced in vitro should be useful sources of genetic material for breeding programmes, especially those which aim to create triploid cultivars.

Eucarpia Symposium on Fruit Breeding and Genetics

Igor V. Bartish, Vitaly I. Korkhovoy, Yelena L. Fomina, Yoong K. Lim

Malus, apple breeding, tetraploidy, in vitro culture, organogenesis, oryzalin

https://doi.org/10.17660/ActaHortic.1998.484.95