<i>In vitro</i> Production of Virus-Free Sweet Potato [<i>Ipomoea batatas</i> (L.) Lam] by Meristem Culture and Thermotherapy

Abstract

Viral disease is the major factor causing significant yield loss in sweet potato. Production of disease-free clones by tissue culture technique increases yield and income of farmers. Meristems from three varieties of sweet potato were cultured at different combinations of BAP, GA₃ and NAA in MS basal medium. Among the combinations, 1 mg/l BAP and 1 mg/l GA₃ with 0.01 mg/l NAA resulted in 66.67% shoot induction for Awassa-83 and Guntute while 63.33% shoot induction was obtained using 1 mg/l BAP, 2 mg/l GA₃ and 0.01 mg/l NAA for Awassa local. There was 100% sweet potato virus elimination from all the three varieties by meristem culture as observed by using NCM-ELISA technique. Shoot thermotherapy was done for Awassa-83 and Awassa local at 37°C for 31 days and 88.89% and 100% SPFMV and SPCSV virus elimination was achieved for the two varieties, respectively. Best shoot multiplication was obtained in MS medium containing 2 mg/l BAP for Awassa-83 (5.26 ± 0.02 shoots/explant) and Awassa local (5.12 ± 0.02 shoots/explant). For Guntute it was 2.48 ± 0.03 shoots/explant on 3 mg/l BAP. The best root length was 9.5 ± 0.10 cm, 9.68 ± 0.02 cm, and 11.03 ± 0.02 cm for Awassa-83, Awassa local and Guntute, respectively on growth regulators free ½ MS medium. The highest number of roots per shoot (6.34 ± 0.01) was obtained from Awassa-83 on 0.1 mg/l IBA. Acclimatizations were 100%, 91.11% and 90.10% for Guntute, Awassa-83 and Awassa local, respectively. This work indicates the practical applicability of plant tissue culture using meristem culture and thermotherapy to produce virus-free planting materials of sweet potato.