Isolated microspore culture in eggplant and inducing heart-shaped embryos

In many crops, androgenesis is one of the most common methods for in vitro haploid induction. The most effective technique in this system is the isolated-microspore culture, in which haploid cells are reprogrammed to follow the sporophytic pathway. But this pathway has been stopped at the globular shape stage of embryogenesis in eggplant, and efforts are still being made to overcome this problem. In this study, the effects of different concentrations of gum arabic, sucrose, and plant growth regulators (6-Benzylaminopurine, BAP, and 1-Naphthaleneacetic acid, NAA) were evaluated on isolated microspore cultures from two cultivars of eggplant. In cultivar Ricarda, the highest number of microspore-derived calli (711.4 per Petri dish) was produced when 2000 mg/l gum arabic, 2% sucrose, 0.5 mg/l BAP, and 0.5 mg/l NAA were used together. By combining 2600 mg/l gum arabic, 2% sucrose, and 0.5 mg/l BAP and NAA, the cultivar Chantale produced the most calli (230.33 per Petri dish; 5.27-fold higher than the control (43.73 per Petri dish). In addition, the results showed that heart-shaped embryos could be produced in eggplant. The culture of microspores of cultivar Ricarda in NLN medium supplemented with 2600 mg/l of gum arabic, 2% sucrose, 0.5 mg/l BAP, and 0.5 mg/l NAA led to the developmental progression of some of the globular structures. In fact, the globular embryos were induced to develop into heart-shaped embryos, which is a promising step forward in the process of eggplant microspore embryogenesis.