In vitro multiplication and genetic stability of two species of Micranthocereus Backeb. (Cactaceae) endemic to Bahia, Brazil

The two targeted species of this study, Micranthocereus flaviflorus subsp. densiflorus and M. polyanthus subsp. alvinii, are endemic to the state of Bahia and have ornamental value. The main goal of this work was to micropropagate these species and to evaluate the genetic stability of the regenerated plants. To do so, shoots originated from in vitro germinated plants were inoculated in MS/2 (Murashige, Skoog, Physiol Plant 15:473–497, 1962) media containing 1.34 μmol L−1 of α-naphthaleneacetic acid (NAA) for morphogenesis induction. This was repeated for three consecutive subcultures, and the subcultured shoots were designated by order of production as S1, S2 and S3. Retention of morphogenic potential and acceleration of organogenic response was observed after the three subsequent propagation events, so that if shoots were used as explant source the in vitro propagation of M. flaviflorus could be achieved in 90 days and that of M. polyanthus could be optimized to 60 days of duration. In order to perform genetic stability analysis along subcultures, ISSR markers were used and genetic variation between shoots of each subculture and their donor plant was measured with Jaccard’s similarity coefficient. This analysis revealed high genetic stability in the in vitro propagation of all the donor plants of M. flaviflorus and M. polyanthus in regards to three consecutive shoot subcultures, in which similarities were 100% for both species. The study of a greater number of subcultures is suggested to assess morphogenesis potential and genetic fidelity in long term.