In vitro plant regeneration from seed explants of wild groundnut species (Genus Arachis, Section Extranervosae)

In vitro regeneration of wild groundnut species from Section Extranervosae (Arachis villosulicarpa, A. macedoi, A. retusa, A. burchellii, A. pietrarel lii, A. prostrata, A. aff. prostrata and a new species) was examined for th e purpose of germplasm renewal and conservation. Seeds of different ages, s tored at the seed bank of CENARGEN/EMBRAPA were either inoculated on cultur e medium or used as a source of embryo axis and cotyledon explants. Whole s eeds failed to germinate on MS either without growth regulators (MS0) or su pplemented with 10 mu M TDZ. Embryo axes cultured on MS0 produced only sing le plants. In the presence of 8.8 mu M BAP these explants showed multi-shoo t formation. Cotyledons cultured on MS supplemented with 110 mu M BAP devel oped adventitious shoots through direct organogenesis. Plant regeneration w as obtained from A. villosulicarpa, A. macedoi, A. retusa, A. burchellii an d A. pietrarellii both from embryo axes and cotyledons. Explants from A. pr ostrata and A. aff. prostrata did not produce regenerants. Rooting of shoot s was induced in the presence of 5.4 mu M NAA. Primary plants derived from these explants were further multiplied by culturing nodal segments on MS me dium plus 2.7 mu M NAA.