Direct somatic embryogenesis and organogenesis in cultured immature zygotic embryos of Pisum sativum L.

Nine cultivars of Pisum sativum L. were screened for their ability to develop somatic embryos and buds from immature zygotic embryos cultured in vitro. In certain cultivars, such as «Bonnaire» and «Davina», high frequency regeneration was achieved via direct somatic embryogenesis or organogenesis, depending on the composition of the medium. Embryogenesis was achieved when zygotic embryos were plated in darkness for 4-5 weeks on MS medium (Murashige and Skoog, 1962)containing 43 µM NAA, thiamine hydrochloride (15 µM), nicotinic acid (40 µM)and arginine (60 µM). However, the percentage of somatic embryos obtained depended on the cultivar used. These embryos developed into plantlets when cultured on MS + 0.01 M KNO 3 supplemented with 15 µM IBA and 2.2 µM BAP. Direct organogenesis was obtained when MS containing 16 µM NAA, 13.3 µM BAP and 0.2 µM TIBA was used. Regenerated shoots were rooted on the same medium, but without TIBA. Following transfer to soil, the plants developed normally and set seed. Histological studies revealed that proliferating somatic embryos or buds originated directly from the cotyledons, without an intermediate callus stage. The cultivars «Bemol» and «Mini» were among the lines that could not be regenerated