Decreased rnase activity under high temperature is related to promotion of self-pollen tube growth in the pistil of the Japanese flowering cherry, prunus × yedoensis ‘somei-yoshino’

Abstract

Prunus × yedoensis Matsum. ‘Somei-yoshino’ is one of the most popular flowering cherry cultivars in Japan. However, because flowering cherries have strict self-incompatibility (SI), it is difficult to develop selfing families or inbred lines for breeding and genetic studies. SI in Prunus is achieved through arrest of self-pollen tube growth in the style by ribonuclease S-RNase. To determine a suitable way to overcome SI in Prunus, we examined the influence of hot water immersion on RNase activity in the style of ‘Somei-yoshino’. When the styles were immersed in 20°C, 30°C, and 40°C water baths, their RNase activity was not significantly different from that of untreated styles (P > 0.05); however, it significantly decreased in styles heated in 50°C water baths (P < 0.01). Furthermore, the RNase activity decreased with an increase in the incubation time (e.g., 1, 3, and 5 min). Additionally, heat treatment at 50°C promoted the growth of self-pollen tubes in the style. Some selfpollen tubes even reached the bottom of the style. The high temperature treatment with reduced RNase activity can overcome stylar SI in Prunus.