Effect Of Paclobutrazol (PP₃₃₃) On The Floral Bud Differentiation Of Cucumber Cotyledonary Nodes Cultured In Vitro

The mechanism of flowering is one of the hottest fields in plant developmental biology. The whole course of floral bud differentiation includes stages of the physiological changes and the morphological differentiation. This paper focused on the latter.Paclobutrazol (PP333), a kind of triazole compounds, is the inhibitor of gibberellins (GAs) biosynthesis. In this paper, the effect of PP333 was studied during the course of flower differentiation of cucumber cotyledonary nodes cultured in vitro by histological method. The results were shown as belows: Inducement on floral differentiation with PP333 treatment, the sutible medium was MS supplemented with PP333 (0.3 mg / L), the optimized stage was the first 24 hours after the seedlings were decapitated, and the most effective stage PP333-precultured was the first 6 hours period after decapitation. As a result, the floral bud inducement with PP333 mainly worked in short time, and the process of accumulation also exhibited some promotion on floral differentiation. The treatment with PP333 improved floral differentiation and the floral buds formation, the percentage of floral bud formation was 40.74% and it was 2.6 times of the control. The results of observation by light microscopy showed that the treatment with PP333 enhanced the primordial differentiation with the percentage of numbers of floral primordia / explants up to 1.4 times of the control, and decreased the tendency of primordial abortion, and facilitated the normal growth of the plant. The treatment with PP333 had little effect on the initiation and formation of the primordium, this was consistent both on the tissue level and the organ level.The results suggested that PP333 maybe affected the floral initiation, promoted the primordium differentiation, be advantage to the normal growth and development of plant.