关键词: 荷花, 花型, 重瓣化, 石蜡切片, 花芽分化

Abstract:

Five forms of flower are included in lotus (Nelumbo nucifera). The single flower is the primitive type of lotus flowers, followed by semidouble, double, duplicated and thousandpetalled flower. To understand the molecular mechanism underlying the flower doubling in Nelumbo, it is necessary to investigate morphologically the origin of different flower forms. We studied the differentiation of lotus floral buds by paraffin section of five cultivars in Nnucifera, representing the five forms of flower, ie.‘Dan Sajin’ (single), ‘Da Sajin’ (double), ‘Zhongshan Hongtai’ (duplicated), ‘Zhizun Qianban’ (fullydouble) and ‘Qianban Lian’ (thousandpetalled), respectively. The anatomical examination showed that the differentiation of the sepal and petal primodia shared a similar pattern, but the stamen and carpel primordia were distinct in differentiation. The normal differentiation processes of stamen and carpel primordia were observed in the flower buds of single, double and duplicatedpetalled cultivars. However, in ‘Zhizun Qianban’, a fullydouble cultivar, all the primordial stamens and carpels were transformed into the petals. The thousandpetalled cultivar didn’t produce either stamen primordia or carpel primordia but developed the tiny petals instead. These results suggested that the petals of doubleflowered lotus were mainly derived from the petalody of stamens, followed by pistils. For the thousandpetalled cultivar, further molecular studies are needed to understand the origin of the petals and the role of receptacle in flower doubling of lotus.

Key words: Nelumbo nucifera, Flower form, Flower doubleness, Paraffin section, Floral differentiation