Unraveling the fertilization mechanism focusing on a removal of the of an unusual membrane enclosing sperm cells in flowering plants.

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K21432
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 44:Biology at cellular to organismal levels, and related fields
• 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): 2020-07-30 – 2024-03-31
• Keywords: シロイヌナズナ / 花粉管 / 精細胞 / 内部形質膜 / 栄養核

Outline of Final Research Achievements

In flowering plants, sperm cells are delivered to the egg cell within the ovule through a narrow tubular structure called the pollen tube, facilitating fertilization. During pollen-tube growth, a pair of sperm cells are enclosed by the Inner Vegetative Plasma Membrane (IVPM) and connected with the pollen tube vegetative nucleus to form a functional assemblage termed Male Germ Unit (MGU). It has been hypothesized that immediate IVPM removal from the sperm cells plays a crucial role in double fertilization via exposing the surface of sperm cell upon pollen tube discharge into the ovule. However, the dynamics and molecular mechanisms underlying this process were not well understood. In this study, we successfully observed the dynamics of the IVPM removal and identified several factors necessary for its IVPM fragmentation using a combination of live imaging techniques in Arabidopsis thaliana, genetic approaches, and the use of inhibitors.

Free Research Field

植物生殖学

Academic Significance and Societal Importance of the Research Achievements

私たちの生活を支える穀物や果実を収穫するためには多くの場合受精が必要となる。また、有用なゲノムを組み合わせて臨んだ形質の植物を作出する際も植物の受精は欠かせない。精細胞を覆う内部形質膜は適切なタイミングで崩壊することによって重複受精に必須の役割を果たすと考えられている。本研究によって明らかとなった花粉管放出時の精細胞が示した内部形質膜崩壊の動態や、崩壊に必要な因子の知見は、重複受精を理解するための基礎的な知識として植物発生学における普遍的な重要性をもつ。