Somatic Embryogenesis in Common Bermudagrass
A culture method capable of plant regeneration is necessary to utilize tissue and cell culture techniques in bermudagrass research [Cynodon dactylon (L.) Pers.], but no plant regeneration has been reported in the literature. The objectives of this research were to: a) establish an in vitro culture system for callus induction and plant regeneration of common bermudagrass, and b) examine the mode of regeneration. Expiants from young leaves were cultured on Murashige and Skoog (MS) and B5 media supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D) (2.0, 4.0 mg/1) and kinetin (0.2 mg/1). Immature inflorescences at different developmental stages (0.5, 1.0, 1.5, 2.0, and 2.5 mm long) were grown on MS and N6 media (2.0 mg/1 2,4-D; 2 or 6% sucrose). The most leaf callus growth occurred on MS containing 2.0 mg/1 2,4-D without kinetin in the dark. However, calli induced from immature inflorescences grew better on N6 than on MS. A higher sucrose concentration (6%) affected the compactness of embryogenic callus and frequency of embryogenic callus compared with a lower concentration (3%). Calli originating from leaf or node tissues were soft and white. These nonembryogenic calli consisted of large, tubular cells. Upon transfer to hormone-free medium, they readily produced roots without shoot formation.