In Vitro Regeneration of Valencia-type Peanut (Arachis hypogaea L.) from Cultured Petiolules, Epicotyl Sections and Other Seedling Explants1

Abstract

Abstract This study evaluated plant development via direct organogenesis from in vitro-cultured young seedling tissues of cultivated peanut, especially the valencia-type peanut. Complete plants were regenerated from in vitro-cultured petiolule-with-blade-attached explants, leaflet segments, and epicotyl andpetiole sections. Multiple shoots arose on Murashige and Skoog medium (MS) supplemented with 6-benzylaminopurine (BA) (5–25 mg/L) plus 1-naphthaleneacetic acid (NAA) (0.5–3 mg/L). After 30 d culture on 25 mg/L BA + 1 mg/L NAA, 1.6 buds or shoots/explant were regenerated from the petiolule-with-blade-attached explants. Comparable numbers of shoots were obtained from epicotyl sections of the first node region of the seedling after 60 d culture using 10 mg/L BA + 1 mg/L NAA. Leaflet segments and petiole sections were less responsive for shoot formation. Excised shoots developed roots in vitro upon transfer for 15 d to MS medium supplemented with NAA at 1 mg/L. Plantlets were transferred to soil and grown in a greenhouse to maturity. A wide range of cultivated peanut genotypes was evaluated for organogenic responsiveness, using the petiolule-with-blade-attached explant source. Only valencia-type cultivars, or a hybrid derivative with a Valencia background, were responsive with this regeneration system.