Developmental and Structural Section
Little, Stefan A. , Christianson, Michael L. , Jernstedt, Judy .
When is apical damage most effective in inducing vegetative short-shoot branches in Ginkgo biloba?
Rare cases of vegetatively-branched short-shoots of Ginkgo biloba are reported in the older literature; these document that vegetative lateral shoots can be produced on short-shoots in addition to the usual reproductive laterals. Last year, we reported that such vegetative branching can be experimentally induced by damage to, or removal of, the short-shoot apical meristem. However, a variety of factors must be determined for a more complete understanding of the developmental biology of vegetative lateral branching and for an efficient practical application of this experimental approach. In order to document the window of response to such treatment, recent experiments use a time-course of apical meristem ablations beginning in early spring, prior to swelling of terminal buds, and extending to late in the season. These experiments assay the response of short-shoots on both mega- and microsporangiate trees; previous experiments, and reports in the literature, documented the branching ability of short-shoots in megasporangiate plants only. Additional factors include the importance of the age of the short-shoot, and whether the short-shoot is located in a juvenile or reproductive portion of the canopy. The experimentally generated branched short-shorts test our preliminary observations that vegetative laterals arise in axils of bud scales or the latest foliage leaves, and not in positions where reproductive laterals arise. Since short-shoots of Ginkgo share many morphological similarities with the typically unbranched shoots of cycadophytes, our results not only probe ginkgophyte developmental potential but provide a cycadophyte-like model amenable to experimentation. We intend such studies of the living clades of seed plants to stimulate consideration of branching and of potential variation in developmental fating of meristems among extant and extinct seed plants. Supported in part by the Grady L. Webster Memorial Research Fund (MLC) and a Katherine Esau Postdoctoral Fellowship (SAL).
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1 - University of California, Davis, Plant Sciences, One Shields Avenue, Davis, California, 95616-8780, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 551A/Convention Center
Date: Tuesday, August 3rd, 2010
Time: 10:00 AM