Seasonal impact on embryogenic callus induction under subtropical conditions in banana (Musa spp. cv. Grand Naine [AAA])

Gene editing tools for banana crop improvement necessitates efficient embryogenic cell suspensions, which are derived through embryogenic calli (EC). Although many factors are known to influence EC formation, the roles of seasonal effects and environmental factors in EC induction of banana remain unclear. We therefore examined the formation of EC from immature male flower buds (IMFB) collected in each month of the years 2020 and 2022. Among 12 batches examined, IMFB initiated between January and April produced the highest percentage of EC in both years. In 2020, the percent of EC ranges from 8.22 to 12.14, whereas in 2022 the EC percentage ranges from 2.50 to 4.47. IMFB initiated from May to August produced moderate response and those initiated between September and December gave the lowest percentage of EC in both the years. Plants that generated highest percentage of EC underwent transition from vegetative to reproductive phase in autumn and flowered in winter. During this period, environmental factors such as global radiation, relative humidity and temperature were relatively low compared to summer. In contrast, plants that underwent vegetative–reproductive transition under extreme summer conditions and flowered at the end of summer and autumn yielded lowest percentage of EC. Exposure to high temperature and radiation during this period might have altered inflorescence development. Our results indicate that seasonal alterations in environmental factors influence the rate of EC induction. Key Message We explored the optimum months for EC induction. During January to April, the percentage of EC induction was highest. The seasonal impact of environmental factors on EC induction discussed.