TEMPERATURE CONTROLS BOTH GAMETOPHYTIC AND SPOROPHYTIC DEVELOPMENT IN MICROSPORE 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 of pollen-like structures at high frequencies (up to 80% after 7 days in culture). Early stages of both developmental pathways are observed in culture at 25.0 degrees C, and embryos are produced at low frequencies (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 provides a convenient tool for investigating the cellular and molecular mechanisms controlling this developmental switch.