In vitro induction of aneuploid forms of tetraploid grapes by para-fluorophenylalanine

Abstract

Direct induction of hyper- and hypo-tetraploid forms (2n=4x±1 or 4x±2) from tetraploid grapes without crossings may be useful for establishing seedlessness in the seeded cultivars without greatly loosing their vigor and other characters. For the induction, explants proliferated from cultured shoot tips of tetraploid 'Kyoho', 4x 'Rozaki' and hybrids from 'Kyoho'X'4x Rizamato' cross were treated for 30 and 60 days on MS medium supplemented with various concentrations of para-fluorophenylalanine (PFP; 25-150 mg/l), and subcultured for about three months on rooting medium lacking PFP. Of 348 explants including those of control, 233 explants survived. Of the survived explants, 208 tetraploid (2n=4x=76), six mixoploid consisting of cells with 76 and those with less than 76 chromosomes and two aneuploid plants (2n=72 and 69) were identified by the chromosome observation in their root tip cells; chromosomal variation in 17 explants showing no growth and rooting could not be identified. With increase of the PFP concentration, the rates of survived explants and explants showing no growth increased. Treatment of 75-150 mg/l PFP for 30 and 60 days was effective for elimination of a few chromosomes in the tetraploid explants. The result suggested the possibility of somaclonal induction of hyper- and hypo-tetraploids from tetraploid cultivars by PFP treatment in vitro.