Somatic embryogenesis and plant regeneration of turf-type bermudagrass: Effect of 6-benzyladenine in callus induction medium

Abstract

In order to optimize tissue culture conditions for bermudagrass, an important warm-season turfgrass species, tissue culture responses of young inflorescences of a hybrid bermudagrass cultivar `Tifgreen' (Cynodon dactylon×Cynodon transvaalensis) and a common bermudagrass cultivar `Savannah' (Cynodon dactylon) were investigated. When cultured on Murashige and Skoog medium with 4.52 to 13.57 μM (1–3 mg l^-1) 2,4-D, young inflorescence segments yielded non-embryogenic calli which were unorganized and had loosely associated, long tubular cells on the surface. However, inclusion of 6-benzyladenine (BA) in callus induction medium at a level of 0.044 μM (0.01 mg l^-1) induced formation of a compact, nodular embryogenic structure on approximately 20% of the calli. Calli with such a compact embryogenic structure were highly regenerable. When young inflorescences smaller than 0.75 cm were cultured, the embryogenic structure yielded green plantlets with regeneration rates of 79.5% and 83.3%, respectively for the two cultivars. All 96 plants regenerated from calli induced in the BA-containing medium were green and morphologically normal. The embryogenic nature of the compact structure was confirmed by scanning electron microscopy.