An in vitro seed germination protocol for Plukenetia volubilis L.

Plukenetia L. (Euphorbiaceae) is a genus of tropical climbers containing several neglected and underutilized crops. The seeds are oleaginous with a very high percentage of polyunsaturated fatty acids, which are often present in insufficient quantities in human diets. Several species are of horticultural value and crosses may provide plants with increased yield, hardiness and sensorial characteristics. However, the genus is still only scarcely studied and studies of in vitro culture and compatibility are lacking. To ensure rapid rearing of F1 offspring from such crosses and to enable the survival of underdeveloped embryos a protocol for in vitro germination and propagation is needed. Mature seeds of Plukenetia volubilis L. were sterilized and the testa was removed. The endosperm was sectioned transversely, the upper half was removed, and the embryos were inoculated in a Murashige and Skoog medium containing 0.1 mg L-1 6-benzylaminopurine and 3% sucrose. After germination and development of cotyledons, the seedlings were transferred to soil. A 100% germination rate was observed for P. volubilis, with seedlings showing good root and shoot growth, showing that the growth medium is efficient for stimulating germination and that the protocol enables the generation of new plants. Furthermore, the protocol is likely to work for different species of the genus, and for underdeveloped embryos, e.g., resulting from interspecific hybridization. The described protocol provides an efficient method for germinating seeds of P. volubilis and is likely to enable the cultivation of underdeveloped embryos of different species of Plukenetia, overcome seed dormancy and allow for rapid multiplication of Plukenetia.