Meristem culture of selected sweet potato (Ipomoea batatasL. Lam.) cultivars to produce virus-free planting material

SummarySweet potato (Ipomoea batatas L. Lam.) is a staple root crop, consumed as a carbohydrate-rich food source in many tropical countries. The production and productivity of sweet potato is limited by several factors, mainly virus infections. This study was conducted to produce virus-free sweet potato planting material using meristem culture. Meristems without leaf primordia were excised from four virus-positive field-grown local sweet potato cultivars ‘Bellela’, ‘Temesgen’, ‘LO-323’, and ‘Zapallo’. Meristems were cultured in Murashige and Skoog (MS) medium supplemented with different combinations and concentrations of 6-benzylaminopurine (BAP), α-naphthaleneacetic acid (NAA), and gibberellic acid (GA3) for shoot initiation. ‘Bellela’ and ‘Temesgen’ exhibited 100% shoot initiation on 5 mg l–1 BAP, 0.01 mg l–1 NAA, and 1 mg l–1 GA3, although the shoots were bushy. ‘LO-323’ showed 90% shoot initiation with the best shoot quality on 2 mg l–1 BAP, 0.01 mg l–1 NAA, and 1 mg l–1 GA3. Shoot tips and nodes from in vitro-grown plantlets were cultured on BAP (0, 0.5, 1.0, or 2.0 mg l–1) or on BAP (0, 0.5, 1.0, or 2.0 mg l–1) + kinetin (Kin; 0, 0.1, 0.5 or 1.0 mg l–1) for multiple shoot formation. The best shoot proliferation was obtained on MS + 0.5 mg l–1 BAP + 0.5 mg l–1 Kin. In vitro-grown shoots were cultured on MS medium containing 0.0, 0.01, 0.1, 0.5, or 1.0 mgl–1 indole-3-butyric acid (IBA). The best root formation was obtained on IBA-free medium. The plantlets thus produced were tested for the presence of ten sweet potato viruses [Sweet potato chlorotic stunt virus (SPCSV), Sweet potato feathery mottle virus (SPFMV), Sweet potato mild mottle virus (SPMMV), Sweet potato chlorotic fleck virus (SPCFV), Sweet potato caulimo-like virus (SPCaLV), Sweet potato mild speckling virus (SPMSV), C-6 (a flexuous rod virus), Sweet potato latent virus (SwPLV), Sweet potato virus G (SPVG), and Cucumber mosaic virus (CMV)] using nitrocellulose membrane enzyme-linked immunosorbent assay (NCM-ELISA). Ninety-nine percent of plantlets were free from all viruses.