Figure 2.

Effect of different periods of heat-stress treatment on suspensor formation in rapeseed microspore culture. A, The frequencies of embryos with long, normal-looking suspensors ≥30 μm (dark gray bars), embryos with short suspensor-like structures (irregular-shaped appendant structures or uniseriate structures <30 μm; light gray bars), or embryos without a suspensor (white bars), B, Total embryo yield. All cultures were started with a density of 40,000 microspores per milliliter. After the heat-stress treatment, cultures were kept at 25°C. For the determination of total embryo yield (B), embryos larger than 0.4 mm were counted after 16 d of culture when the largest embryos had already reached 3 mm. Data are the means of five replicate experiments, each with three 6-cm petri dishes per treatment and 3 mL of original microspore suspension per dish. Bar = ±se.