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Abstract Detail



Pteridology

Kuo, Li-Yaung [1], Chen, Cheng-Wei  [2], Hung, Yu-Ling [3], Ko, Chia-Wen [2], Li, Fay-Wei [1], Chiou, Wen-Liang [4], Wang, Chun-Neng [5], Huang, Yao-Moan [2].

Heterochronic response to antheridiogen could explain the mating behavior shifts in polyploid ferns.

Ferns are the second largest group among extant vascular plants and have evolved a complex mating system. Diploid ferns often develop dioecious gametophytes through the regulation of a sex-determination pheromone – antheridiogen. Mature gametophytes secret antheridiogen that induce nearby young gametophytes to differentiate into males (i.e. with only sperm-producing antheridia), and thus promote outcrossing. In contrast, in polyploid ferns, gametophytes tend to be bisexual, having both antheridia and archegonia simultaneously, and under the most extreme situation, a single gametophyte can self intragametophytically, resulting in a complete homozygous sporophyte. However, to date the mechanism for such different modes of gender expression between diploid and polyploid ferns has remained unclear. To shed light on this, we compared the gametangium development in autohexaploidy Deparia lancea and its conspecific diploids. We found that in mix-aged gametophyte populations, the hexaploids are biased being bisexual, while the conspecific diploids displayed a higher degree of dioecy. In the further transplant experiments, we found that for the hexaploids, gametophytes in the later developmental stages, which were matured enough to produce archegonia, were most sensitive to antheridiogen, and, on average, produced more antheridia per individual. By contrast, gametophytes of the diploids were most sensitive to antheridiogen during the earlier stage when the notch meristem has not yet developed. Our results imply that the inbreeding syndrome in polyploid ferns can be achieved via delaying sensitivity to antheridiogen, and, consequently, their gametophytes can produce both male and female gametangia at the same developmental stage. Our finding is the first to provide direct evidence supporting that a mating system switch in ferns involves a heterochronic regulation on antheridiogen sensitivity.


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1 - Cornell University, Boyce Thompson Institute, Ithaca, NY, 14853, USA
2 - Taiwan Forestry Research Institute, Division of Silviculture, Taipei, Taiwan
3 - National Taiwan University, Instituite of Plant Biology, Taipei, Taiwan
4 - Dr. Cecilia Koo Botanic Conservation and Environmental Protection Foun, Pingtung County, Taiwan
5 - National Taiwan University, Institute of Ecology and Evolutionary Biology, Tapei, Taiwan

Keywords:
fern
antheridiogen
mating system
Inbreeding
Polyploid
Gametophyte
Deparia lancea.

Presentation Type: Oral Paper
Session: 5, Pteridology I
Location: 108/Mayo Civic Center
Date: Monday, July 23rd, 2018
Time: 11:30 AM
Number: 5014
Abstract ID:516
Candidate for Awards:Edgar T. Wherry award


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