Wang, Ruohan , Zhang, Zhixiang , Wang, Jianzhong .
Flowering and pollination patterns of Magnolia denudata with emphasis on anatomical changes in ovule and seed development.
Magnolia denudata is an excellent ornamental and ecologically important tree that exhibits low fecundity because of seed abortion. To better understand the cause of this low sexual reproduction, pistil receptivity and pollen quality were investigated using culture medium and histochemical staining, with emphasis on pollen viability at different flowering stages. Cross-pollination, geitonogamy, and self-pollination were undertaken on flowers of sample trees. We found that flowers produce a large number of pollen grains available for effective pollination. Pollen viability varied at different stages, but was highest during stage 3, in which the stamens detach from the axis, the anthers dehisce, and the gynoecium stigma starts to fade. The duration of pistil receptivity was approximately 5 h. These results indicate that poor fertilisation may occur if the optimum period for pollination is missed or the stigma receives poor-quality pollen grains from stages other than stage 3. Although dichogamy avoids selfing, it has led to considerable geitonogamy. Our anatomical analysis of ovule and seed development further revealed that fertilisation occurred in samples with geitonogamy, but that the embryo degenerated in the torpedo stage. Our results provide new insights into the mechanism of reduced seed set under natural conditions. This work was supported by a grant from the Ph.D. Programs Foundation of Ministry of Education of China (No. 200800220007)
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Floral Biology of Magnolia
1 - Beijing Forestry University, College of Biological Science and Biotechnology, Beijing Forestry University, # 35 Qinghua East Road, Haidian District, Beijing, China , University of British Columbia, Canada, Beijing, 100083, China
2 - Beijing Forestry University, College of Biological Science and Biotechnology, # 35 Qinghua East Road, Haidian District, Beijing, China, Beijing, 100083, China
Presentation Type: Poster:Posters for Topics
Location: Event Tent/Cliff Lodge
Date: Monday, July 27th, 2009
Time: 5:30 PM