Effects of carbohydrate source and BAP concentration on in vitro morphogenesis of four Rose genotypes
Résumé
Roses are known to be recalcitrant to in vitro regeneration methods. Regeneration
via de novo shoot organogenesis or somatic embryogenesis is the key step for the successful
process of genetic transformation and functional validation of genes. To improve the de
novo shoot organogenesis process in rose genotypes, it is essential to control the
physiological state of donor plants in order to prepare explant tissues and increase their
regeneration abilities. Therefore, the aim of this study was to improve donor plant in vitro
culture and mainly: (1) to understand the effect of media composition, including cytokinin
and carbohydrate sources on cultured node morphogenesis, (2) to verify a possible
interaction between genotype and media content and (3) to evaluate the best composition
of the medium for a long in vitro storage to manage collections by increasing subculture
period of four donor plant rose genotypes. All genotypes were able to increase their
multiplication rate when they were subcultured on medium supplemented with
benzylaminopurine, (BAP) 3 mg/L and high concentration of carbohydrate except
sorbitol. Fructose or glucose was the best carbohydrate sources for multiplication but the
optimal dose depends on genotype. The maximum of shoot elongation was obtained on
medium including 0.5 mg/L benzylaminopurine and 0.1 mg/L gibberellic acid
supplemented with 30 g/L fructose or glucose. Callus formation and rooting were
enhanced by high concentration of fructose, glucose or sucrose. Maltose and sorbitol
allowed an extended storage time for all genotypes. On the other hand, leaf explants issued
from medium containing high concentration of benzylaminopurine and lacking
gibberellic acid were able to regenerate adventitious shoot after transfer on shoot
regeneration medium if combined with the optimal carbohydrate type and concentration
which allow multiplication for the mother plants.