Influence of exogenous polyamines on the secondary somatic embryogenesis of cork oak (Quercus suber L.)

ABSTRACT

Quercus suber L. is the main woody tree species in the Mediterranean basin. The in vitro regeneration from adult material, through primary somatic embryogenesis, is a well-known process, but the use of secondary somatic embryos for plant regeneration remains a very sparsely studied process. The main objective of this work is to explore the cork oak regeneration potential by using the secondary somatic embryogenesis process. Mainly, in this work, we report the polyamine effect. Explants used consisted on primary mature embryos, derived from leaves rejuvenated by epicormic shoot of the Moroccan Quercus suber. Three different polyamines were added to the basal medium, which was composed by macronutrients of N₃₀K, 30 g/l glucose, and 7 g/l agar. Three polyamines, Putrescine, Spermine, and Spermidine, were added to the basal medium at 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6 mg/l. Explants were tested after 8 weeks. Morphological analysis showed that the medium with 0.4 mg/l Spermidine provided the best result for secondary embryos, which corresponds to a very significant (p < 0.05) increase of 375%. The number of secondary embryos directly formed was 2.70 ± 0.51. Similarly, the optimum concentrations for high number of clusters (0.50 ± 0.11) and embryo clusters (1.43 ± 0.35) were increased by 145% and 158%. The addition of the polyamine also acted on the quality of embryos formed. A very significant (p < 0.05) increase in the size of secondary embryos was observed compared to the medium without polyamines. Spermidine showed the greatest increase (about 38%).

KEYWORDS:

• Cork oak
• secondary embryos
• somatic embryos
• Putrescine
• Spermidine
• Spermine

Disclosure statement

No potential conflict of interest was reported by the author(s).

Authors contributions

Naouar Ben Ali: acquisition of data, conception and design, methodology, formal analysis, writing, editing, and finalizing the manuscript; Rajae Benkaddour, Safaa Rahmouni, Ouafaa Hamdoun, Ibtissam Boussaoudi and Latifa Azaroual: Substantial contributions to the conception of this article, analysis and interpretation of data; Mustapha Hassoun: drafted the manuscript and critically revising it for important intellectual; Alain Badoc and Patrick Martin: critical review of important intellectual & editing the manuscript; Ahmed Lamarti: conception, design and editing the manuscript. All authors have read and approved the final version of the manuscript.

Data availability statement

The data that support the findings of this study are available from the corresponding author [Naouar Ben Ali] upon reasonable request.

Additional information

Funding

This work was funded by Hassan II Academy of Science and Technology (Morocco) through the project entitled “Study of the genomic variability of the cork oak (Quercus suber L.) and clonal multiplication by somatic embryogenesis”.