FACTORS AFFECTING SOMATIC EMBRYOGENESIS INDUCTION AND DEVELOPMENT IN FEIJOA SELLOWIANA BERG.

Abstract

Feijoa sellowiana Berg. (Myrtaceae) is a small tree known as feijoa or pineapple guava. In recent years, this species has gained horticultural and consumer recognition due to the qualities of its fruits which possess high levels of vitamin C and iodine. Somatic embryogenesis induction in feijoa was first achieved by our group in 1990 from mature zygotic embryos and, since then, several improvements have been made in the protocol for somatic embryo induction and conversion. However, some drawbacks still persist in the process of plant regeneration through somatic embryogenesis in feijoa such as the high number of anomalous somatic embryos formed, the low frequencies of plant somatic embryo conversion, and the reduced potential of adult explants to undergo somatic embryogenesis. Trying to overcome these problems several lines of investigation are being followed at our lab with the objective of improving the quality of the somatic embryos and, at the same time, to understand the factors responsible for these negative aspects. Recent experiments have shown that the culture of somatic embryos in abscisic acid for 4 weeks before conversion increased the levels of storage lipids and proteins in the cotyledons of the somatic embryos as well as the number of somatic embryos able to develop into plantlets. Moreover, it was found that somatic embryos of feijoa usually possess a morphologically variable suspensor-like structure that, in the first stages of development, is quite similar to the suspensor of the zygotic embryos. Another line of investigation indicated that an auxinic shock instead of a continuous culture in the presence of auxin reduced the levels of anomalous embryos formed. The role of the genotype on somatic embryo formation and some preliminary results about somatic embryogenesis induction from young leaves of adult micropropagated genotypes will also be presented.