CHARACTERIZATION OF THE MORPHOLOGICAL EVENTS IN THE DIRECT SOMATIC EMBRYOGENESIS OF Coffea arabica L. GENOTYPE LEAF EXPLANTS

The vegetative multiplication of Coffea genotypes can be obtained by direct somatic embryogenesis. However, little is still known regarding the occurrence of this process in C. arabica. The objective of this study was to characterize the events during the formation of somatic embryos of this species by direct somatic embryogenesis. For this purpose, foliar explants from three genotypes were inoculated into a culture medium with ½ the concentration of MS salts, plus the addition of 10 µM 2-Isopentenyladenine, and maintained in the dark at 30°C. A sequence of morphological events was observed leading to the formation of somatic embryos. First, the explants formed rounded structures on their edges starting from 15 days after inoculation in the culture medium. Following this, the event of oxidation occurred simultaneously in the foliar explants and in the structures formed, starting from 60 days of cultivation. The last event was the initiation of somatic embryos, which started 90 days after inoculation. All the events occurred in a single culture medium.