Effect of indole-3-acetic acid and kinetin on tuberisation parameters of different cultivars and transgenic lines of potato in vitro

The effect of indole-3-acetic acid or kinetin on the weight and number of microtubers formed was studied on single node cuttings of seven different potato (Solanum tuberosum L.) cultivars as well as transgenic lines harbouring rolB or rolC genes under control of the patatin class I (B33) promoter. Plants were cultivated in vitro in the dark on solidified MS medium containing 1 to 8% sucrose with or without phytohormones. Most of the nontransformed potato cultivars and transgenic lines responded to hormone application by an increase in tuber yield. Auxin and cytokinin acted differently: IAA increased predominantly the tuber size while kinetin increased the number of tubers. RolC transformants displayed an altered response to sucrose and especially to auxin. The degree of phytohormone effect on tuberisation parameters depended on sucrose content of the medium and potato genotype.