Production of cotyledon-type somatic embryos directly from immature cotyledonary explants of Camellia sinensis (L.)

SummaryAttempts were made to produce cotyledon-type somatic embryos from immature cotyledonary explants of Camellia sinensis (tea). Seeds of the tea cultivar ‘TRI 2043’ were collected at successive developmental stages, and separated into groups depending on the morphological complexity of the seed coat. Further separation was based mainly on the size (diameter) of the cotyledons in each seed (early, mid and late immature: stages 1–3; intermediate: stage 4; mature: stage 5). To determine the most suitable stage for direct somatic embryogenesis, sterilised cotyledons at various developmental stages were placed on MS basal medium containing 2 mg l–1 6-benzyl aminopurine (BAP) and 0.2 mg l–1 naphthalene acetic acid (NAA). The results indicated that immature cotyledons, 10 mm in diameter (stage 3), were most responsive for the production of typical (cotyledon-type) somatic embryos. Cytological examination revealed that typical somatic embryos exhibited gradual tissue differentiation. Immature (stage 3) cotyle...