Ganger, Michael , Sturey, Tiffany , Bahny, Beth .
Induction and conversion in Ceratopteris richardii, a gender-labile fern: more pieces to the puzzle.
Ceratopteris richardii is a homosporous fern whose gametophytes may develop into either males or hermaphrodites. Development of an undifferentiated spore into a male, a process called induction, is strongly influenced by the presence of antheridiogen, a gibberellin-like hormone secreted by hermaphrodites. In the absence of antheridiogen or in the presence of both antheridiogen and abscisic acid (ABA), spores are likely to develop into hermaphrodites. Males have been shown to remain male in the continued presence of antheridiogen, but may convert to hermaphrodites with its removal, in a process called conversion. Two experiments will be discussed. The first concerns the determinants of male gametophyte size. Spores of determined sizes from two strains, wild type (RNWT1) and highly male (him1), were sown onto agar containing 0x, 0.5x, 1x, and 2x strength antheridiogen and allowed to grow for 3 weeks under 24 hour grow lights at 24-28 degrees Celsius. Spore size was positively, though weakly, related to male gametophyte size, while antheridiogen concentration was negatively related to ultimate male gametophyte size. No difference in size was observed between C. richardii strains. These results suggest that antheridiogen may influence gender through slowing growth. Slow growing gametophytes would be expected to bias toward male development, while faster growing gametophytes would develop as hermaphrodites. This would be due to the resource requirements of the hermaphrodite since it supports sporophyte growth. The second experiment concerns the role of ABA in conversion. Three-week old males were exposed to several concentrations of ABA, 0 microM, 1 microM, 10 microM, 100 microM, and 300 microM. Males in low concentrations of ABA were more likely to convert and converted more quickly than those in higher concentrations. While ABA is antagonistic to antheridiogen during early development, it appears to function similarly to antheridiogen during conversion.
Log in to add this item to your schedule
1 - Gannon University, Biology, 109 University Square, Erie, PA, 16541, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Westminster Room/Chase Park Plaza
Date: Tuesday, July 12th, 2011
Time: 9:50 AM