In vitro tetraploid induction of the gooseberry (Ribes glossularia L.)

• Colchicine had high phytotoxic effects on gooseberry plants, despite this, it was possible to generate polyploid plants. • Compared to the diploid plants, the tetraploids of 'White Triumph' had a lower multiplication rate. • Compared to the diploid plants, the shoots of tetraploid of both 'White Triumph' and the AGR9 had a lower rotting frequency. Polyploidisation is a tool widely used in breeding programs of many crop plants. After doubling the number of chromosomes, favorable traits are very often enhanced due to the increased dose of genes determining the desired characteristics. This study aimed to develop an in vitro polyploidisation method and obtain tetraploids of gooseberries. For this purpose, in vitro cultures of five gooseberry genotypes were initiated and the media for their multiplication were optimized. For polyploidization, shoot explants were incubated in the dark for two weeks on cultivar-specific multiplication media containing one of the following antimitotic agents: colchicine, trifluralin, oryzalin, or amiprophos-methyl. The strongest phytotoxic effects were observed for oryzalin and trifluralin (all the explants died). Tetraploids that survived were obtained for two genotypes, four in 'White Triumph' and three in AGR9. The polyploidisation efficiency was 1.7 % and 1.9 % in 'White Triumph' and AGR9, respectively. Compared to the diploid plants, the tetraploids had a lower multiplication rate and the number of shoots useful for rooting. It is the first report of obtaining gooseberry tetraploids.