PRODUCTION OF COCOA PLANTS (THEOBROMA-CACAO L) VIA MICROGRAFTING OF SOMATIC EMBRYOS

The possibilities for in vitro regeneration of cocoa plants have been limited. Somatic embryos can differentiate from cotyledonary cells, but their conversion into plants has remained largely unsolved. In the present study, we attempted micrografting of somatic embryos to seedling rootstocks. Different conditions were analyzed for the rootstocks and embryos, and it was found that complete plant regeneration needed about 10 mo. The best results were obtained using a simple culture medium, 3-wk-old rootstocks, and somatic embryos without cotyledons. Histologic events associated with the graft union were also analyzed. Cells, mainly from the rootstock, initiate cellular division in different patterns, producing a callus at the graft junction. Within this region some cells differentiated into zylem and phloem, establishing vascular connection in the graft. Afterward, micrografted plants start to grow and differentiate new leaves and roots allowing for transfer to soil.