The development of gamma ray-mutated rice lines is a solution for introducing genetic variability in indica rice varieties already being used by farmers. In vitro gamma ray (⁶⁰Co) mutagenesis reduces chimeras and allows for a faster selection of desirable traits but requires the optimization of the laboratory procedure. The objectives of the present work were sequencing of matK and rbcL, the in vitro establishment of recalcitrant rice embryogenic calli, the determination of their sensitivity to gamma radiation, and optimization of the generation procedure. All sequenced genes matched perfectly with previously reported matK and rbcL O. sativa genes. Embryogenic calli induction improved using MS medium containing 2 mg L⁻¹ 2,4-D, and regeneration was achieved with MS medium with 3 mg L⁻¹ BA and 0.5 mg L⁻¹ NAA. The optimized radiation condition was 60 Gy, (LD20 = 64 Gy) with 83% regeneration. An immersion system (RITA^®, Saint-Mathieu-de-Tréviers, France) of either 60 or 120 s every 8 h allowed systematic and homogeneous total regeneration of the recalcitrant line. Other well-known recalcitrant cultivars, CR1821 and CR1113, also had improved regeneration in the immersion system. To our knowledge, this is the first study reporting the use of an immersion system to allow for the regeneration of gamma-ray mutants from recalcitrant indica rice materials.

Vaccinium consanguineum, blueberry native to Costa Rica, presents nutritional and antioxidant qualities that makes it a fruit of high medicinal and nutritional value. Its adaptation to the highlands of the country places it as a species of interest, so that having techniques for obtaining clonal planting material are advisable. The objective of this research was to continue the development of the protocol for the micropropagation of this species. The in vitro establishment stage was validated and the use of more effective disinfectants such as the combination of enzymatic soap (5 ml.l(-1)) and sodium hypochlorite (3% i.a.) was included at this stage. It was possible to establish field material in the greenhouse by sowing plants, rooting cuttings and seed germination without using any type of growth regulators, 100% survival and adaptation to environmental conditions of the greenhouse were observed. A sign of the adaptation shown by the plants harvested in the field was that 40% presented flowering and fruiting. With the aseptically established stakes, the effect of three growth regulators in 50% WPM culture medium, BA (0, 3, 5, 10, 15 and 20 mgl-1) and Z (0, 0.5 mgl-1), both cytokinin being effective at concentrations of 3 mgl-1 and 0.1 mgl(-1) respectively, but the best procedure for sprouting and multiplication consisted in exposing the micro-cuttings to a heat shock at 5 degrees C for 15 days, using the same medium with 120 gl(-1) of sucrose and 0.1 mgl(-1) of Z. Subsequently, the materials were transferred to the liquid WPM medium supplemented with 30 gl(-1) sucrose and 0.1 mgl(-1) of Z with a filter paper bridge, which reduced the oxidation of the explants and improved the nutritional conditions of the culture, being reflected in higher growth and better appearance of the outbreaks.