Influence of Gamma Irradiation on Pollen Viability, Pollen Tube Growth, and Fruit Development in Tomato (Solanum lycopersicum L.)

The goal of this study was to assess whether irradiated pollen technology could be used in tomato breeding research. The effects of irradiation on pollen viability, fruit set rate, and embryo formation were investigated. For this purpose, pollens were exposed to gamma rays of 0, 50, 100, 200, 300, and 400 Grays (Gy). The effect of irradiation on pollen viability and tube growth was found to be significant based on counting and measurements performed under in vitro conditions at 24, 48, 72, and 144 h after irradiation. Fruit set and embryo formation in seeds were evaluated 30 days after pollination with pollen irradiated at different doses. It was determined that increasing the irradiation dose resulted in reduced pollen viability and tube length. Endosperm formation was detected in all seeds after 50 Gy of irradiation. However, 50 Gy had no effect on gynogenesis stimulation. Therefore, 100, 200, and 300 Gy doses stimulated embryo formation without endosperm, while 400 Gy of irradiated pollen did not support fruit to set. These results indicate the importance of harvesting time to obtain viable embryos. It should be retracted to an earlier time since late harvest resulted in necrosis of globular embryos on the 30^th day after irradiation. Pollination with one-day-old irradiated pollen was more suitable for gynogenesis induction. The results showed that the irradiated pollen technique can be applied in tomato breeding studies, especially in terms of purifying the obtained breeding lines in a shorter time. In particular, determining the appropriate induction dose for gynogenesis depending on the genotype is important for stimulation efficiency.