Nymphaea prolifera has a peculiar and unusual asexual reproductive mechanism called floral “vegetative viviparity” which allows it to produce new seedlings directly from its flowers. Understanding the formation process of floral vegetative viviparity and the effect of endogenous hormones on its formation will provide a basis for further elucidating the mechanism of vegetative viviparity in N. prolifera and the biology of asexual plant reproduction. Morphological observation, paraffin sectioning and scanning electron microscopy were used to analyse the morphological characteristics of vegetative viviparity flowers of N. prolifera as the test group and normal flowers as the control group. Elisa assay was used to compare the deviation in endogenous hormones between “nutrient propagules” from vegetative viviparity flowers and pistils from normal flowers. Nutrient propagules were formed on the receptacle in the original pistil area and are already formed at the stage of flower bud differentiation. In contrast to the flowers of normally developing water lilies, vegetative viviparity flowers only retained receptacle, sepals, and other organs; they lack petals, stamens, and pistils. Then, the nutrition propagules could continually develop leaf and flower buds. The leaf buds were mostly triangular and curled, while the flower buds were mostly hooked or conical and had many ciliated tissues on the surface. A vegetative viviparity growing flower's nutritional propagules could give rise to several asexually reproducing buds, which could then proceed to reproduce in a second and third generation once they reached a particular stage of development. Endogenous hormone assays showed that indoleacetic acid (IAA) and gibberellin (GA) levels were not significantly different between normal and vegetative viviparity water lily flower nutrient propagules, whereas jasmonic acid (JA), cytokinin (CTK) and abscisic acid (ABA) levels were systematically higher in vegetative viviparity water lily flower trophozoites. Vegetative viviparity flowers of N. prolifera had obvious differences in tissue structure compared to normal flowers. During flower bud differentiation, the gynoecium of N. prolifera flowers was replaced by the nutritive propagules to form vegetative viviparity flowers. Compared with those of the gynoecium of normal flowers, three endogenous hormones such as jasmonic acid (JA), cytokinin (CTK) and abscisic acid (ABA) levels were consistently higher in the nutritive propagules of vegetative viviparity flowers, which may contribute to the formation of the floral vegetative viviparity phenomenon.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |