A histological comparison of the development of pollen and female gametophytes in fertile and sterile Cryptomeria japonica |
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Authors: | Yoshihiro Hosoo Eri Yoshii Kenji Negishi Hideaki Taira |
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Institution: | (1) Chair of Climate Change Science for Forestry and Water-Resources, Graduate School of Science and Technology, Niigata University, 8050 Ikarashi 2-no-cho, Niigata 950-2181, Japan;(2) Chair of Ecosystem Science, Graduate School of Science and Technology, Niigata University, 8050 Ikarashi 2-no-cho, Niigata 950-2181, Japan;(3) Department of Production and Environmental Science, Faculty of Agriculture, Niigata University, 8050 Ikarashi 2-no-cho, Niigata 950-2181, Japan |
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Abstract: | To determine a possible mechanism causing male and female sterility in Cryptomeria japonica male and female cones were collected from a C. japonica, tree, ShinDai2, that lacks pollen release and fertile seeds and specimens were processed to examine the development of pollen
and female gametophytes using light microscopy and field emission scanning electron microscopy. Pre-meiotic development proceeded
normally, but the formation of aberrant meiotic products was observed in cones of both sexes. In sterile microsporangia, heterogeneous
microspore populations ranging from monads to polyads gave rise to mature pollen grains of non-uniform size. These pollen
grains were covered with an amorphous layer and adhered to each other. In addition, they remained in the microsporangia and
were not released even after the onset of pollen dissemination from fertile trees. In the ovules of sterile female cones,
megaspores with abnormal shapes, numbers, and sizes formed, and the development of female gametophytes was arrested at the
free nuclear or archegonium formation stages. These gametophytes collapsed, and no fertile embryo was generated. Results indicate
that meiotic defects are important in the sterility mechanism. |
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Keywords: | Cryptomeria japonica Female gametophyte Meiosis Pollen Sterility |
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