|Waters, Mark -|
|Tiley, Anna -|
|Kramer, Elena -|
|Langdale, Jane -|
|Scotland, Robert -|
Submitted to: Plant Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 11, 2013
Publication Date: March 15, 2013
Citation: Waters, M.T., Tiley, A.M., Kramer, E.M., Meerow, A.W., Langdale, J.A., Scotland, R.A. 2013. The corona of the daffodil Narcissus bulbocodium is distinct from the orthodox floral whorls.. Plant Journal. doi: 10.1111/tpj.12150. Interpretive Summary: Using gene expression studies and anatomical investigations, the coronas of the daffodil flower is shown to originate from tissue located between the male reproductive parts and the flower petals. This occurs late in the development of the flower, after all other parts are developed. However, the floral organ identity genes expressed in the corona tissue are more similar to those expressed in the male reproductive parts than in the petals.
Technical Abstract: The structural homology of the daffodil corona has remained a source of confusion throughout the history of botany. Over the years it has been separately referred to as a modified petal stipule, stamen and tepal. Here we provide new insights from anatomy and molecular studies to clarify the early developmental stages and position of corona initiation in Narcissus bulbocodium. We demonstrate that the corona initiates as six separate anlagen from hypanthial tissue between the stamens and perianth. SEM images and serial sections demonstrate that corona initiation occurs late in development, after the other floral whorls are fully developed. To define more precisely the identity of the floral structures, daffodil orthologues of the ABC floral organ identity genes were isolated and expression patterns were examined in perianth, stamens, carpel, hypanthial tube and corona tissue. Coupled with in situ hybridization experiments, these analyses showed that the pattern of ABC-class gene expression in the corona is more similar to that of the stamens than that of the tepals. In combination our results demonstrate that the corona of the daffodil Narcissus bulbocodium exhibits stamen-like identity, develops independently from the orthodox floral whorls, and is best interpreted as a late elaboration of the region between the petals and stamens associated with epigyny and the hypanthium.