ARS | Publication request: A Cytochemical and Developmental Comparison of Soybean (Glycine Max L.) and Tobacco (Nicotiana Lxs8) Floral Nectaries

Submitted to: International Congress On Sexual Plant Reproduction Proceedings
Publication Acceptance Date: August 18, 2004
Publication Date: August 18, 2004
Citation: Horner, H.T., Healy, R.A., Thornburg, R.W., Palmer, R.G. 2004. A Cytochemical And Developmental Comparison Of Soybean (Glycine Max L.) And Tobacco (Nicotiana Lxs8) Floral Nectaries. International Congress On Sexual Plant Reproduction Proceedings. Abstract No. 66.

Technical Abstract: Floral nectaries of soybean and tobacco were studied microscopically from their initiation to beyond their active secretory stages. Both differ greatly in their time frame of development and their manner of secretion. Both secrete nectar through special stomates. Soybean nectaries form in several days, and become secretory and degenerate within 24 hours, whereas tobacco nectaries form and become secretory in about 12 days. They may remain active beyond this time. Phloem fingers innervate the soybean nectary, and its special parenchyma contains little starch accumulation prior to and during secretion. In contrast, tobacco nectary is not innervated by any vasculature and its special parenchyma becomes engorged with starch prior to secretion. Histochemical localization of proteins and RNA in special parenchyma of both nectaries shows intense staining, indicating highly metabolic cells. Soybean nectary secretion is described as holocrine, in that during secretion its cells undergo apoptosis. Tobacco nectary cells remain intact after secretion before they eventually wither. A number of tobacco genes have been identified as being expressed during the life of its nectary. Some of them have a reasonably high level of homology in soybean. In situ hybridization is being used to determine spatial and temporal patterns of expression of these genes in both nectaries.