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Big bluestem ( Andropogon gerardii Vitman) and little bluestem [ Schizachyrium scoparium (Michaux) Nash.] are native to the North America and are important forage grasses and ornamental grasses. Both grasses are proposed as ideal biomass producers for cellulosic ethanol production. To apply genetic transformation, which is an important tool for incorporating desirable agronomic traits into plants to both species, however requires an efficient and reproducible regeneration protocol. We used mature caryopses from big and little bluestem as explants and tested the effect of various combinations of 2, 4-dichlorophenoxyacetic acid (2, 4-D) (1, 2, 3, 4 or 5 mg l −1 ) and kinetin (KT) (0, 0.1 or 0.2 mg l −1 ) on embryogenic callus induction with LS as the basal medium. The highest percentage of embryogenic calli induction occurred on medium containing 2, 4-D alone at 2 mg l −1 for ‘Bison’ and on medium containing 4 mg l −1 2, 4-D alone for ‘Bonilla’ big bluestem. For little bluestem, the highest percentage of embryogenic callus induction occurred on medium containing 3 mg l −1 2, 4-D plus 0.1 mg l −1 kinetin, suggesting that addition of KT is beneficial. Shoot regeneration took place on LS basal medium without any plant growth regulator for both species, although the addition of KT increased both regeneration frequency and the number of shoots produced per callus. Rooting of shoots reaching about 2 cm long occurred readily with or without α-naphthaleneacetic acid (NAA). Rooted plantlets were all successfully established in the soil.

Indiangrass [ Sorghastrum nutans (L.) Nash.] is native to the North America and is an important component of the original tall grass prairie. It is also an important ornamental and forage grass. Recently, it has been proposed as an ideal biomass producer for cellulosic ethanol production. Genetic transformation is an important tool for introducing important agronomic traits into plants, but an efficient and reproducible in vitro regeneration protocol is a prerequisite for successful genetic transformation. In this report, we used mature caryopses as explants and tested the effect of various combinations of 2,4-dichlorophenoxyacetic acid (2,4-D) (1–5) and kinetin (KT) (0, 0.1, and 0.2) on embryogenic callus induction using LS basal medium. Caryopses cultured on media supplemented with 2,4-D alone generally outperformed those cultured on media supplemented with both 2,4-D and kinetin for embryogenic callus induction. The best treatment is LS basal medium supplemented with 3 mg l −1 2,4-D. LS basal medium supplemented with KT of 0, 0.5, 1, 2 or 5 mg l −1 were tested for regeneration efficiency which was shown to increase as the KT concentration increased. The quality of the shoots produced on the medium containing KT at 5 mg l −1 , which produced the highest regeneration frequency appeared to be lower as leaves become vitrified. Shoots were moved to a rooting medium containing either 0 or 0.1 mg l −1 α-naphthaleneacetic acid (NAA). Rooted plantlets were then transferred to soil-containing pots and were placed in a mist room for 1 week before they are transferred to a normal greenhouse where they all survived. The reported regeneration protocol is very efficient and highly reproducible in spite of the heterogeneous nature of the tested cultivar; thus it should be suitable for genetic transformation.