Influence of plant preservative mixture (PPM)(TM) on adventitious organogenesis in melon, petunia, and tobacco

The influence of PPM(TM) on somatic embryogenesis in melon, adventitious sh oot organogenesis in petunia, and androgenesis in tobacco was studied by cu lturing explants in regeneration media supplemented with 0, 2, 5 or 10 ml l (-1) PPM for 8-12 wk. The percentage of melon cotyledon explants that produ ced callus and somatic embryos and the number of embryos per explant were r educed when incubated in embryo initiation and embryo development media con taining more than 5 ml l(-1) PPM. Less PPM was required to inhibit petunia shoot organogenesis. The number of shoots and number of buds per Petri dish were reduced 3-6.9-fold when leaf explants were incubated in shoot regener ation medium containing more than 2 ml l(-1) PPM. In contrast, the addition of up to 10 ml l(-1) PPM to tobacco anther culture medium had no effect on androgenesis. Our results suggest that the influence of PPM on plant regen eration depends on the plant species. We recommend that experimenters exami ne a range of PPM concentrations when using it for the first time on an unt ested plant species.