Evaluation of apple cv. Jeromine raised on in vitro and conventionally propagated clonal apple rootstocks

Apple is a significant cash crop that is cultivated in the temperate areas around the globe. In the past, seedling rootstocks were used for raising commercial apple orchards however, the increasing demand for apple has led to a rising interest in clonal rootstocks due to early maturity, good fruit quality, disease resistance, and wider temperature adaptability. Traditional propagation methods for rootstock multiplication are time-consuming and labor-intensive, which has prompted the adoption of micro-propagation as a viable alternative for large-scale production of uniform, disease-free, and high-quality plant material. In vitro propagation protocols for apple clonal rootstocks viz., M7, M9, MM106, MM111, and Merton793 have been developed but tissue culture propagated rootstocks are not widely accepted due to concerns regarding graft incompatibility and risk of inducing genetic variability, necessitating the evaluation of regenerated plants for successful commercial utilization. In the present study, no significant variability was observed at morpho-physiological level between tissue culture raised and conventionally propagated clonal rootstocks grafted with ‘Jeromine’. To overcome the limitations of traditional phenotypic observation, further confirmation was done using RAPD and SCoT markers. Out of 33 RAPD primers, 18 primers were successful in DNA amplification resulting in 64 amplicons, out of which 58 were monomorphic. Nineteen out of 36 SCoT primers resulted in DNA amplification leading to 83 amplicons, out of which 36 were monomorphic. Overall, the apple cv. Jeromine trees raised on in vitro and conventionally propagated apple rootstocks grafted were significantly similar at morpho-physiological and molecular levels. These findings support the recommendation of tissue culture-raised clonal rootstocks to farmers for commercial apple cultivation, as they offer the potential for increased yields and improved profitability in high-density apple plantations.