Plant regeneration in Kentucky bluegrass (Poa pratensis L.) via coleoptile tissue cultures

Plant regeneration in Kentucky bluegrass (Poa pratensis L. cv. Touchdown) via culture of seedling tissues was investigated. When coleoptile, leaf, and stem sections of dark-germinated seedlings were cultured on Murashige and Skoog (MS) medium, different types of callus were produced, depending on the expiant source and growth regulator combinations. Only compact-friable callus (type 3) and moderately compact, friable callus (type 2) produced shoots upon subculture. The nonstructured watery callus (type 4) produced roots without shoots. Shoot differentiation from callus tissues was highest when the culture medium contained 0.2 mgL(-1) picloram + 0.01 mgL(-1) α-naphthaleneacetic acid (NAA). Calli grown from coleoptiles had higher shoot regeneration frequency (32%) than that obtained from either stem sections (12%) or young leaf tissues (2%) of the same seedlings. Some organogenic callus lines produced exclusively green plants, while others produced albino shoots or a mixture of green and albino shoots. The green plants were multiplied in a medium containing 0.1 mgL(-1) BAP plus either 0.2 mgL(-1) picloram or 0.1 mgL(-1) indole-3-acetic acid (IAA). Over 90% of the cultures in the shoot proliferation medium produced roots in 4 weeks. The rooted plants were successfully established in soil medium and grown in the greenhouse.