Variations in the satellite DNA content of Cucumis melo in relation to dedifferentiation and hormone concentration.

Total DNA from Cucumis melo contains a 1.706 satellite DNA which can be resolved into two components; one of these components has a higher temperature of melting (component I) then the other component II). In this study, we have further investigated these components by thermal denaturation and by Eco R1 digestion. Component I reveals a homogeneous melting profile and is only partially cleaved by Eco R1, whereas component II reveals a heterogeneous melting profile and is entirely digested by Eco R1. A possible mitochondrial origin for component II is discussed. When an in vitro culture of root tissues from Cucumis melo was initiated or when the phytohormone (NAA) concentration of established cultures was modified, a new satellite DNA (1.719) appears transitorily and the satellite DNAs already present in seedlings undergo quantitative and possibly qualitative variations. Satellite DNAs therefore seem to be involved in the response to some physiological variations.