TEMPERATURE CONTROLS BOTH GAMETOPHYTIC AND SPOROPHYTIC DEVELOPMENT INMICROSPORE CULTURES OF BRASSICA-NAPUS

Temperature controls the developmental fate of isolated Brassica napus microspores in vitro. Culture at 32.5 degrees C leads to sporophytic development and the formation of embryos. Here we show that culture at 17.5 degrees C leads to gametophytic development, and the formation o f pollen-like structures at high frequencies (up to 80% after 7 days i n culture). Early stages of both developmental pathways are observed i n culture at 25.0 degrees C, and embryos are produced at low frequenci es (0.7%) at that temperature. Culturing B. napus microspores at 32.5 degrees C versus 17.5 degrees C brings the switch from gametophytic to sporophytic development under simple experimental control and provide s a convenient tool for investigating the cellular and molecular mecha nisms controlling this developmental switch.