Variability of Flavonol Contents during Floral Morphogenesis in the Poppy Papaver somniferum L.

We studied the contents of flavonols (kaempferol and quercetin) in the meristem of vegetative and generative apices of the main plant shoot in floral Papaver somniferum L. mutants, as well as in the normal plants at successive stages of flower development. Five stages of flower development were distinguished. Flavonols (kaempferol and quercetin) were present in all flower organs at all stages of floral morphogenesis we studied. However, their contents and distribution in different organs and at different stages of flower development markedly varied. No significant differences were found in the contents of flavonols in the meristems of vegetative and generative apices of the main shoot in the lines of floral mutants, as well as between the lines with different amounts of vegetative phytomeres. In the plants with normal flower structure, the contents of flavonols (kaempferol + quercetin) sharply increased with the beginning of differentiation of flower organs, i.e. from stage 3, to reach a maximum in the open flower, when gametogenesis is terminated and fertilization takes place. The level of flavonol contents in the petals (upper part) and stamen was at a maximum at all stages of flower development, while that in the gynaecium was at a minimum. The kaempferol : quercetin ratio was shifted towards quercetin at successive stages of flower development, most significantly in the stamens. The involvement of flavonols in the regulation of floral morphogenesis at stages of flower organs differentiation and functioning is discussed.