Study of factors affecting direct shoot regeneration of pear (Pyruscommunis L.)

Conventional methods of pear breeding, largely based on intra- and inter-specific hybridization, aredifficult because pear is highly heterozygous, polygenic and has a long juvenile period. Geneticimprovements of pear cultivars are possible through induction of mutations and gene transfer by geneticengineering. A general prerequisite for these approaches is to establish an efficient plant regenerationsystem. In the present study, the effect of two basal media (MS and NN) and different concentrations ofTDZ (0, 2.5, 5, 7.5 µM) or BAP (0, 4, 8, 16 µM) in combination with NAA (1 µM) on direct shootregeneration of two pear (Pyrus communis L.) genotypes 'Bartlett' and 'Dargazi' was investigated. Theobtained results showed that 'Dargazi' had higher rates of shoot regeneration than 'Bartlett' and in bothcultivars the highest percent of shoot regeneration was observed from lower sections of the leaves.Although the highest percent of shoot regeneration in 'Bartlett' (38%) was attained in the NN mediumcontaining 2.5 µM TDZ and 1 µM NAA, the differences in shoot regeneration between this medium andthe NN media containing 5 or 7.5 µM TDZ and 1 µM NAA were not significant. The highest percent ofshoot regeneration in 'Dargazi' (56%) was obtained in NN medium containing 7.5 µm TDZ and 1 µmNAA. It can be concluded that genotypes, explant types and culture media composition could effect ondirect shoot regeneration of pear.

Keywords:

direct shoot regeneration , pear , thidiazuron