Different regeneration potential of mesophyll protoplasts from cultivated and a wild species of tomato.

Mesophyll protoplasts were isolated from leaves of three cultivars of Lycopersicon esculentum (L.) Mill., namely "Hilda 72", "Rutgers" and "Rentita", and from the wild tomato species Lycopersicon peruvianum (L.) Mill. Protoplasts from L. peruvianum divided and grew actively in a liquid medium according to Zapata et al. (1977), whereas protoplasts from the tomato cultivars "Hilda 72" and "Rutgers" showed comparable rates for cell division only, when the content of major elements in this medium was reduced to one half of the original concentration and when mannitol as osmoticum was replaced by glucose. In "Rentita" protoplasts no cell division could be observed in about 15 different modifications of the five basic culture media tested. The morphogenetic potential of these tomato cells was assessed by comparing the root and shoot formation of protoplasts and of leaf explants. L. peruvianum exhibited the highest potential. Calli derived from protoplasts regenerated roots on Murastrige-Skoog agar containing 1 μM benzylaminopurine (BAP) plus 10 μM indole-3-acetic acid (IAA) and 0.1 μM BAP plus 1 μM IAA. Shoot formation occurred in the combinations of 10 μM BAP with 0.1, 1.0, and 10 μM IAA. Plantlets regenerated from the L. peruvianum calli could be grown in soil. No shoots or roots were regenerated from calli of "Hilda 72" and "Rutgers" protoplasts in all combinations of BAP and IAA tested in the range from 0.1 μM to 100 μM, thus indicating the rather low morphogenetic potential of these protoplasts as compared to protoplasts from L. peruvianum leaves.