Alleviation of hyperhydricity of sugarcane plantlets produced in RITA® vessels and genotypic and phenotypic characterization of acclimated plants

AbstractThe effect of employing a RITA® system in one or both of somatic embryo induction and germination stages was investigated, and it was deemed far superior to a semi-solid (agar) substrate in terms of in vitro plant yields for sugarcane genotype N41. Approximately 18,000 plants/leaf roll were obtained in vitro in 12weeks, when both culture stages were undertaken using temporary immersion, compared with approximately 2000 plants/leaf roll produced on semi-solid medium. However, due to hyperhydricity, only ~34% of the plants produced in RITA® survived acclimatization. To overcome this, and realize the potential yields of the RITA® system, various culture conditions were investigated, viz. nutrient and sucrose supplies, a rockwool substrate and the immersion regime. Of these, increasing the resting time between immersions from 1min/12h to 1min/72h, and lowering MS nutrient to 1/2 strength, proved the most beneficial, resulting in 60% acclimation success. Genetic fidelity of these plants was investigated by AFLP analyses where only 0–0.9%, of polymorphic bands were scored compared with the conventionally- propagated N41 control. Phenotypic characterization of plants grown in the field for 6months showed that, although all in vitro derived plants had a reduced stalk diameter relative to the control, there were no significant differences regarding stalk mass, height and population