Gametophyte contribution to sporophyte growth on the basis of carbon gain in the fern <Emphasis Type="Italic">Thelypteris palustris</Emphasis>: effect of gametophyte organic-matter production on sporophytes |
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Authors: | Yoshiaki Sakamaki Yoshio Ino |
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Institution: | (1) Department of Biology, School of Education, Waseda University, 1-6-1 Nishiwaseda, Shinjuku-ku, Tokyo 169-8050, Japan |
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Abstract: | At an early stage of growth gametophytes support the sporophytes of ferns. Young sporophytes become independent of gametophytes
when the first leaves develop. Although large fern gametophytes produce multiple archegonia simultaneously, only one sporophyte
is typically established on one gametophyte. The number of sporophytes is believed to be controlled in two possible directions,
from gametophyte to sporophyte or from preceding sporophyte to another sporophyte. To investigate the effects of gametophytes
on their sporophytes, we studied the relationship between organic matter production by gametophytes and the growth of young
sporophytes of Thelypteris palustris. We cut gametophytes in half (CGs) to reduce the gametophytes’ production of matter. There was no significant difference
between the growth of sporophytes on intact gametophytes (IGs) and that on CGs. According to our estimates, based on the rate
of organic matter production, the large gametophyte was able to produce two or more sporophytes. The resources required for
CGs to make similar-sized sporophytes was twice that for IGs. In polyembryony each of the multiple sporophytes was similar
in size to the single sporophytes. Resource limitation does not seem to explain why fern gametophytes establish single sporophytes. |
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Keywords: | Pteridophytes Gametophytes Sporophytes Organic matter production Thelypteris palustris |
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