Callus induction and high efficiency plant regeneration via somatic embryogenesis in paspalum

Paspalum vaginatum Swartz (seashore paspalum) is a warm season grass that can be used for turf, forage, erosion control, or bioremediation. The species is a sexual diploid, but produces less than 5% viable seed, which poses problems for genetic enhancement by conventional breeding methods. The selection of somaclonal variants is one alternative method for genetic improvement. The objective of this study was to develop a standard tissue-culture regeneration protocol for this species. Immature inflorescences of nine seashore paspalum ecotypes were used as explants for the induction of embryogenic callus in two controlled laboratory experiments during 1993 to 1994 in Georgia. Five levels of (2,4-dichlorophenaxy)acetic acid (2,4-D; 0.0, 1.0, 2.0, 6.0 mg L-1) and three 6-benzylaminopurine levels (BAP; 0.0, 1.0, 2.0 mg L-1) were tested for callus induction during 1993 and four levels of 2,4-D (2.0, 3.0, 6.0, 10.0 mg L-1) during 1994 in a factorial experiment with all treatment combinations. BAP effects were not significant for all ecotypes except Adalayd. The 2,4-D response varied by ecotype, but all ecotypes responded to the lowest rate (1 mg L-1). A significant embryogenic response was obtained in all ecotypes with 1 mg L-1 BAP in combination with 0.5 to 2.0 mg L-1 alpha-naphthaleneacetic acid (NAA). HI-1, Mauna Key, PI 299042, and K3 were highly embryogenic and PI 509021 and Adalayd were less embryogenic. High frequency plant regeneration of five ecotypes (PI 509021, HI-1, Mauna Key, Adalayd, PI299042) was successfully achieved. The protocol from callus induction to plant regeneration for seashore paspalum has been streamlined to be effective and efficient.