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

• Published in: South African journal of botany Vol. 77; no. 3; pp. 685 - 692
• Main Authors: Snyman, S.J., Nkwanyana, P.D., Watt, M.P.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.08.2011
• Subjects: Acclimation; agar; amplified fragment length polymorphism; Genotypic fidelity; germination; hyperhydricity; leaf rolling; Phenotypic characterization; plantlets; Somatic embryogenesis; sucrose; sugarcane; Temporary immersion; Temporary immersion; Somatic embryogenesis; Acclimation; Genotypic fidelity; Phenotypic characterization
• ISSN: 0254-6299; 1727-9321
• DOI: 10.1016/j.sajb.2011.03.004

The 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 12 weeks, 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 1 min/12 h to 1 min/72 h, 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 6 months 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. ► Results confirm that in vitro yields are greater RITA® vessels instead of agar. ► 1/2 MS and 1 min/72 h immersion regime overcame shoot hyperhydricity in RITA®. ► The benefit of such a long resting time between immersions has not been reported. ► The established protocol yielded ± 6000 acclimated plants/leaf roll. ► AFLP and phenotypic tests showed few differences between ex-vitro and control plants.