The Effect of Slow-grown in Vitro Storage Under Different Light Spectra on Banana Plantlets Cv. Prata Catarina (AAB).

Maintaining updated in vitro plant subcultures is essential for commercial micropropagation and tissue culture research. In unusual situations, the subcultures can be delay and the slow-growth in vitro storage technic could be applied to reduce the loss of plant material. The present study aimed to evaluate the slow-growth in vitro storage of banana plantlets (‘Prata Catarina’; group AAB) under different light spectra. Shoot cultures in MS medium without plant growth regulators were maintained under blue (B), red (R), red plus blue (R2B), and white (CW) light spectra (25°C ± 2°C; 50 µmol m -2 s -1 ) for up to 140 days. The plantlets maintained under the R, CW, and R2B spectra did not survive after 140 days of in vitro slow-growth storage. The plantlets maintained under the B spectrum survived after 140 days of in vitro slow-growth storage and showed little browning.

In vitro conservation and genetic diversity of threatened species of Melocactus (Cactaceae)

The high endemism, the natural habitat degradation, and the over-collection for ornamental purposes have led some species such as Melocactus paucispinus and M. glaucescens to be threatened with extinction. The use of in vitro conservation techniques, such as slow growth storage, promotes the preservation of genetic diversity with integrity. The goal of this study was to establish a strategy for in vitro conservation of apical segments of the cladode of M. paucispinus and M. glaucescens and evaluate the genetic diversity of individuals from in vitro germinated plants. For such purpose, different concentrations of the plant regulator ancymidol and the osmotic agent sucrose on the inhibition of the in vitro growth were tested, and the genetic diversity of M. paucispinus and M. glaucescens individuals stored in vitro was evaluated. Sucrose showed higher efficiency in the reduction of growth than ancymidol for both species. However, due to the reduction in survival percentage, the use of sucrose over 75 g L− 1 in the in vitro conservation of both species for 360 days is not recommended. In the genetic diversity analysis, 76.92% of polymorphic loci (P), expected heterozygosity (He) = 0.276 and Shannon index (S) = 0.414 were observed for M. paucispinus. For M. glaucescens, the observed values were P = 95.38%, He = 0.228 and S = 0.369. These values observed here were higher than those previously found for the natural populations of these species, which demonstrated that this in vitro collection showed genetic diversity and can be used in management and reintroduction programs of these species.

In vitro conservation of ornamental plants

The market of flowers and ornamental plants is dependent on the diversification of species and the availability of high quality propagation materials. Actually, in vitro culture techniques performance a prominent role in the multiplication and maintenance of commercially propagated ornamental plant species, and are promising for the production of thousands of high quality plants in relatively short term. In addition, when market demand for a particular species is low or zero in a specific period of the year, in vitro culture techniques allow the conservation of cultures under aseptic conditions, by Slow Growth Storage (SGS), from a few weeks to one year (or more), without affecting their viability and potential regrowth. This can be achieved by modifying the constitution of the culture medium and the maintenance conditions of in vitro cultures. Obviously, the success of the technique depends on greatly on the physiological characteristics of the species to be conserved, as well. Once a SGS protocol is optimized, the expenses labor, the possibility of contamination and the probability of somaclonal variation can be reduced markedly.