Behavior of Opuntia ficus-indica (L.) Mill. Heat-Stressed Microspores Under "In Vitro" Culture Conditions as Evidenced by Microscopic Analysis

• Published in: In vitro cellular & developmental biology. Plant 2020-02, Vol.56 (1), p.122-133
• Main Authors: Bouamama-Gzara, Badra, Zemni, Hassène, Zoghlami, Néjia, Gandoura, Samia, Mliki, Ahmed, Arnold, Marianne, Ghorbel, Abdelwahed
• Format: Article
• Language: English
• Subjects: Acids; Aluminum; Androgenesis; Anthers; Biomedical and Life Sciences; Cell Biology; Cell culture; Cell division; Culture media; Developmental Biology; Dichlorophenoxyacetic acid; Embryos; Flowers & plants; Fruits; Gibberellic acid; Heat shock; Heat stress; Heat treatment; Life Sciences; Maturation; Microscopic analysis; Microspores; Opuntia ficus-indica; Plant Breeding/Biotechnology; Plant Genetics and Genomics; Plant Sciences; PLANT TISSUE CULTURE; Plantlets; Pollen; Scanning electron microscopy; Thidiazuron; Variance analysis
• ISSN: 1054-5476; 1475-2689
• DOI: 10.1007/s11627-019-10032-4

When constrained by in vitro culture conditions, microspores from Opuntia ficus-indica (L.) Mill. (Barbary fig) anthers were forced to stall out their gametophytic pathway and switch towards androgenesis. Five microspore stages were characterized based on cellular architecture. A relationship was also established between anthers and bud flower features. Anthers were cultured on three culture media containing 2,4-dichlorophenoxyacetic acid, thidiazuron and gibberellic acid at 22°C for 4 wk, followed by heat shock treatment at 32°C or 42°C for 2 wk, and the stressed material was recultured at 22°C for 24 wk in the dark. When anthers were heat shocked at 32°C and 42°C, the cultivated anthers swelled and burst, followed by the microspores flowing onto the expiant surface. Androgenesis occurred directly and indirectly at uni- and binucleate stages. The micromorphology of multicellular, proembryos, globular, torpedo and cotyledonary-like-shaped structures from dehisced anthers was confirmed by environmental scanning electron microscopy. Furthermore, at 42°C, microscopic analysis demonstrated that the non-responsive microspores achieved pollen maturation and more rarely, the emission of a pollen tube. However, 11.4 to 14.4% of the mature pollen grains were converted into pollen embryos. The established system may serve, for the first time, as a protocol to produce microspore embryos in O. ficus-indica. Nevertheless, more efforts are needed to complete the development of diplo-haploid plantlets.