INCREASED INDUCTION OF MICROSPORE EMBRYOS FOLLOWING MANIPULATION OF DONOR PLANT ENVIRONMENT AND CULTURE TEMPERATURE IN CORN (ZEA-MAYS L)

Microspore cultures were initiated from the North American sweet corn hybrid, 'Seneca 60'. Donor plants were grown under two environments. One treatment comprised plants that matured completely in the greenhouse (GH) (28-degrees-C/23-degrees-C: day/night), while in a second treatment donor plants were transferred after four weeks to a growth chamber (GC) (18-degrees-C/15-degrees-C: day/night). Microspores were isolated and divided into two treatment sets: cultured directly at 25-degrees-C, or given a heat treatment of 32-degrees-C for 10 days. Greenhouse-grown plants produced fewer embryo-like structures (ELS) than growth chamber-treated plants regardless of the culture temperature treatment. If the microspores isolated from GC plants were subsequently provided with the initial high culture temperature, the number of ELS that could be recovered was more than doubled compared to the cultures incubated at 25-degrees-C continuously. The high culture temperature treatment also resulted in a higher quality of ELS (more compact), which led to a higher frequency of ELS that survived and were subsequently transferred to regeneration medium. However, while plant regeneration and subsequent selfed seeds were obtained, the frequency was very low and further research is required in this area.