A study of plant polyspermy using Arabidopsis mutants detective in the synergid-endosperm fusion.

2022 Fiscal Year Final Research Report

• Project/Area Number: 20H03280
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 44030:Plant molecular biology and physiology-related
• Research Institution: Yokohama City University
• Principal Investigator: Maruyama Daisuke 横浜市立大学, 木原生物学研究所, 准教授 (80724111)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 花粉管 / 助細胞 / 細胞融合 / 多精 / 被子植物 / 重複受精 / 卵細胞 / 胚乳

Outline of Final Research Achievements

In flowering plants, immotile two sperm cells are delivered by a pollen tube and finally released into one of the two synergid cells secreting pollen tube attractant peptides in the ovule. During pollen tube discharge, sperm nuclei enter the egg cell and the central cell by double fertilization, while the other pollen tube contents (PTC) remain outside of those female gametes. However, we found unusual PTC entry named DEAD-End in fertilized central cell through the observation of thousands of ovules. Non-receptive persistent synergid is absorbed by early endosperm in fertilized ovules (SE fusion). DEAD-End can be caused by reception of second pollen tube by the inactivating persistent synergid after SE fusion. We identified a key factor of SE fusion and demonstrated its prerequisite role in DEAD-End. These results indicate novel polyspermy blocking mechanism in flowering plants and provide molecular insight of unique cell fusion mechanism and morphological plasticity in plant cells.

Free Research Field

植物生殖学

Academic Significance and Societal Importance of the Research Achievements

動物の生殖では、卵に対して多くの精子が同時にアクセスするため、雌雄の配偶子が1対1で受精できるように保証する多精拒否のメカニズムが存在する。被子植物にも同様の仕組みが存在することが示唆されていたが、実態は明らかとなっていない。本研究によって植物の多精拒否のメカニズムの一端が明らかになることで、生物の多様な生殖機構の理解に貢献するとともに、多精を利用した新規の育種技術の開発につながると期待される。