Developmental and Structural Section
Budke, Jessica , Goffinet, Bernard , Jones, Cynthia .
Experimental Manipulation of the Moss Calyptra: The effect of cuticle removal and desiccation on sporophyte development in Funaria hygrometrica.
In mosses and other bryophytes, the sporophyte is small, unbranched, and physically attached to the maternal gametophyte. A cap of gametophyte tissue, called the calyptra, covers the sporophyte apex during early development and throughout seta elongation in mosses. The calyptra is necessary for sporangium formation and ultimately sporogenesis. Calyptra-less sporophytes wilt unless grown in high humidity chambers suggesting that the maternal calyptra may prevent desiccation of the developing sporophyte. We have confirmed that the calyptra is covered by a multi-layered cuticle. Furthermore this cuticle is thicker than the cuticle on all other parts of the moss plant.
A manipulation experiment was carried out to test the role of the calyptra by determining the effect of cuticle removal and desiccation on sporophyte development. A complete block design with three treatments and a control (removal of calyptra, removal then replacement with calyptra intact, removal then replacement with calyptra cuticle removed, un-manipulated control with calyptra intact) was carried out for sporophytes of Funaria hygrometrica at a pre-meiotic developmental stage. Following these manipulations, plants were grown under four humidity levels, ranging from 30 to 99% RH, for 6 hours and then returned to 99% RH for the remainder of their development.
Preliminary results indicate that calyptrae without their cuticle are less effective in preventing desiccation of the sporophyte apex at lower humidity levels; resulting in decreased sporangium development, stunted growth, and sporophyte death. Additionally, measurements of spores per capsule and spore viability are currently underway to quantify the experimental effects on maternal gametophyte fitness and sporophyte reproductive success. We propose that the calyptra and its cuticle provide a unique mode of maternal care, which may have favored a taller moss sporophyte stalk via the seta meristem and increased architectural complexity of the moss capsule.
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1 - University Of Connecticut, Department Of Ecology & Evolutionary Biology, 75 N. Eagleville Rd. U-3043, Storrs, CT, 06269, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Lindell A/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 3:45 PM