SOMATIC EMBRYOGENESIS IN TAMARILLO (CYPHOMANDRA BETACEA): RECENT ADVANCES

Abstract

Cyphomandra betacea (Cav.) Sendtn. is a woody plant of the Solanaceae family commonly known as tamarillo or tree tomato. This species is used mainly for its edible fruits which have a high nutritional value and contain relatively high amounts of the vitamins B6, C, and E and provitamin A. In recent years, different aspects related with somatic embryogenesis induction and somatic embryo development of tamarillo have been studied in our lab, making it a suitable model to understand the cytological and molecular mechanisms involved in this morphogenic process with important applications both for plant cloning and genetic transformation. Several explants of tamarillo have the potential to initiate embryogenic cultures such as mature zygotic embryos and young leaves. Attempts are being made to induce somatic embryogenesis from adult plants with the objective of cloning selected genotypes. To achieve this goal assays with the pith stem and floral tissues are being performed. The ability of different tamarillo genotypes to undergo somatic embryogenesis is also being tested, with preliminary results indicating that some genotypes are more suitable than others for somatic embryo formation. Tamarillo embryogenic calli can be maintained in vitro in an auxinic containing medium for several years. However, some lines of these long-term embryogenic calli are quite unstable in culture and variations in chromosome number have been detected. Following the identification of a protein associated with non-embryogenic calli of tamarillo, somatic embryogenesis induction is under investigation in mutant lines of Arabidopsis thaliana in which this protein is not produced.