Protocol optimization for callus induction and shoot regeneration of Ethiopian rice varieties (Oryza sativa L.)

Rice is the primary food source for the majority of the global population. In African countries, rice is considered a critical cereal crop essential for food security. Rice consumption in Ethiopia has been increasing from year to year, and the demand for rice food is not fulfilled by domestic production, the Ethiopian government imports rice products from Asia. Therefore increasing the production of rice in terms of quantity and quality through modern technology is a recent priority and strategy in the country. This study was, therefore, designed to optimize the protocol for callus induction and shoot regeneration of two Ethiopian rice (X-Jigna and Shaga) varieties. Three media types (LS, N6, and MS) supplemented with different concentrations of 2, 4-D were used for callus induction. The maximum callus induction was observed on MS-media supplemented with 2.5 mg/L for X-Jigna and Shaga varieties, respectively. The lowest callus induction frequencies were recorded on N6-media supplemented with 1.5 mg/L 2, 4-D for both varieties. The highest shoot regeneration for X-Jigna (80.67%) and Shaga (72%) was recorded on MS-media containing a combination of kinetin (2 mg/L) and Naphtalin Acetic Acid (0.2 mg/L). The survival rate of acclimatized plantlets was 100% and 66.6% for X-Jigna and Shaga, respectively. In conclusion, this study is distinctive as, to our knowledge, no other research has addressed the optimization of protocols for the Ethiopian rice varieties, serving as a foundational element for future investigations into rice transformation and breeding in Ethiopia.