Unravelling the structure of cucurbitoid teeth in the Cucurbitaceae

Leaf teeth, i.e. projections of the leaf margin, are common among angiosperms. These structures may differ in several aspects, e.g. in the presence or absence of an associated gland. Cucurbitoid teeth, which have an associated gland, have been reported to species of Datiscaceae, Begoniaceae and Cucu...

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Bibliographic Details
Published in:	Plant systematics and evolution Vol. 306; no. 4
Main Authors:	Gonçalves, Jailma R., Rios, Alex B. M., Dalvi, Valdnéa C.
Format:	Journal Article
Language:	English
Published:	Vienna Springer Vienna 01-08-2020 Springer Nature B.V
Subjects:	Angiosperms Begoniaceae Biomedical and Life Sciences Cucurbitaceae Datiscaceae Developmental stages Epidermis Exudation Glands Leaves Life Sciences Original Article Plant Anatomy/Development Plant Ecology Plant Sciences Plant Systematics/Taxonomy/Biogeography Scanning electron microscopy Sheaths Species Structural analysis Sugar Teeth Vascularization Xylem Secretory structures Guttation Cucurbitoid teeth Hydathodes
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Summary:	Leaf teeth, i.e. projections of the leaf margin, are common among angiosperms. These structures may differ in several aspects, e.g. in the presence or absence of an associated gland. Cucurbitoid teeth, which have an associated gland, have been reported to species of Datiscaceae, Begoniaceae and Cucurbitaceae, all from order Cucurbitales. However, no structural characterization has ever been made to confirm the nature of such associated gland in species of Cucurbitaceae; rather, studies so far have merely reported the occurrence of guttation. We aimed to anatomically characterize and identify the nature of glands associated with cucurbitoid teeth in Cucurbitaceae species. Margin samples of leaves at different developmental stages were obtained from seven Cucurbitaceae species, fixed in FAA and processed following usual procedures in optical and scanning electron microscopies. Saplings of Cucumis sativus were placed in a humidity chamber to induce guttation for ulterior chemical characterization of the exudate. Hydathodes were confirmed to occur in all studied species. Their structure consists of an uniseriate epidermis with water pores, reduced epithem, absent sheath and terminal vascularization being formed exclusively by xylem. The presence of sugars in the exudate, which could lead to mistaking hydathodes for nectaries, was ruled out by glucose strip tests. We have characterized, for the first time, the structure of hydathodes in the Cucurbitaceae, thereby elucidating the structure of the glands associated with cucurbitoid teeth. Investigating tooth structure in the Begoniaceae and Datiscaceae should contribute to better knowing the order through taxonomic and biological perspectives.
ISSN:	0378-2697 1615-6110 2199-6881
DOI:	10.1007/s00606-020-01694-4