RAPD analysis of long term micropropagated rootstock plants of Apple Malling 7

Abstract

Apple is the most dominating fruit crop of Himachal Pradesh, constituting about 40 per cent of total area under fruit crops and about 90 per cent of the total fruit production. Plant tissue culture has encouraged production of quality planting material which is disease free and true to type. Due to current trends in favour of high density apple plantations and to fulfill the requirement of planting material from the farmers, commercially viable <i>in vitro</i> propagation method of semidwarf clonal apple rootstock Malling 7 (M7) was developed by axillary branching, initially developed from shoot tip explants. A few thousand plants were transferred to field conditions. In order to check any tissue culture induced variation in these long term micropropagated plants, the genetic fidelity was assessed using Random Amplified Polymorphic DNA (RAPD) markers. Out of the 20 primers screened, 12 generated a total of 44 scorable and distinct bands with an average of 3.7 bands per primer. All the banding patterns for each primer were highly uniform and monomorphic across <i>in vitro</i> multiple shoot clusters and field transplanted micropropagated plants as well as comparable to the field grown mother clone from which the cultures had been established. Our results have shown that the micropropagation protocol developed by this study is appropriate and applicable for clonal propagation of apple rootstock M7 on large scale over a long period without any risk of genetic instability.