Somatic embryogenesis research in rubber: achievements, challenges and future perspectives

• Published in: Plant cell, tissue and organ culture tissue and organ culture, 2023-05, Vol.153 (2), p.237-255
• Main Authors: Jayasree, Parukuttyamma Kumari, Rekha, Karumamkandathil
• Format: Article
• Language: English
• Subjects: Biomedical and Life Sciences; Biotechnology; Breeding; Callus; CRISPR; Crop improvement; Embryonic growth stage; Embryos; Genetic engineering; Genetic improvement; Genetic modification; Genetic transformation; Genome editing; Latex; Life Sciences; Natural rubber; Plant cells; Plant Genetics and Genomics; Plant Pathology; Plant Physiology; Plant Sciences; Polyploidy; Regeneration; Review; Rubber; Somatic cells; Somatic embryogenesis
• ISSN: 0167-6857; 1573-5044
• DOI: 10.1007/s11240-023-02472-z

Somatic embryogenesis is a totipotency based in vitro phenomenon whereby embryos are induced from plant somatic cells and regenerate into whole plants. This pathway is the only regeneration system for genetic improvement in Hevea brasiliensis (rubber), the prime resource for commercial natural rubber production. The ever increasing global demand for natural rubber have necessitated development of new varieties with increased latex yield, better adaptation to biotic/abiotic stresses and low incidence of tapping panel dryness. The long breeding cycle and narrow genetic base of this crop limits the scope for improving the traits by conventional breeding. Hence, it became imperative to adopt biotechnological interventions for widening the genetic base. Plant regeneration through somatic embryogenesis opens up new avenues for genetic improvement of rubber especially with the advent of advanced genetic engineering techniques. Research on somatic embryogenesis in rubber began in the early 1970s. Since then, substantial progress have been made in laboratories worldwide and several interacting factors affecting callus and somatic embryo induction and plant regeneration were identified. Emphasis was also given for studying the process at histochemical, biochemical and molecular levels. Recently, there has been a shift towards molecular research to understand the mechanism behind somatic embryogenesis. In the present article, the research achievements in somatic embryogenesis in H. brasiliensis during the past 50 years are reviewed with emphasis on the developments over the last 2 decades. Current progress made in various crop improvement methods in rubber such as polyploidy induction, CRISPR gene editing and genetic transformation are also discussed. Key message This review summarizes the progress and limitations associated with rubber somatic embryogenesis over the last five decades. Highlights from histological, biochemical and molecular mechanism were discussed. The potential applications of somatic embryogenesis in advanced research for the genetic improvement of rubber is also reviewed.