Overcoming Self-incompatibility and Pollen Tube Growth of Japanese Flowering Cherry, ‘Somei-yoshino’

Abstract

Self-compatibility is an important trait in plant breeding and genetics. To overcome self-incompatibility (SI) in Prunus × yedoensis ‘Somei-yoshino’, one of the most popular flowering cherry cultivars in Japan, we examined pollen tube growth and adaptability after bud pollination (BP), stigma excision (SE), and hot water immersion (HI: 40°C for 1 min, 40°C for 3 min, 45°C for 3 min, and 50°C for 3 min) treatments. On SE treatment, only a few pollen grains adhered to the cutting surface of the style, and sufficient pollen tube growth was not observed. After BP and HI at 40°C, self-pollen tube growth was arrested at a depth of approximately 4 mm from the stigma, at the center of the style, and it was similar to that of the control pollination (P > 0.05). Thus, these methods were not suitable for overcoming SI in ‘Somei-yoshino’. On the other hand, an increase in self-pollen tube growth (P < 0.001) was observed after HI treatment at 45°C (6.9 mm) and 50°C (8.6 mm), where some of the pollen tubes extended to the bottom of the style. Thus, HI (over 45°C) enabled pollen tube growth in the self-styles, thereby overcoming SI in ‘Somei-yoshino’. However, all flowers subjected to HI treatment at 45 and 50°C had necrotized a few weeks after pollination.