Japan Women’s University
Exploring the mysteries of plant sexual reproduction and terrestrial expansion – Genome sequencing and identification of the mating type-determining gene of the mating algae Himemikazukimo –
Professor Hiroyuki Sekimoto, Department of Chemistry and Life Sciences, Japan Women’s University, Specially Appointed Professor Atsushi Toyoda and Specially Appointed Professor Akisao Fujiyama, National Institute of Genetics, Research Organization of Information and Systems, and Assistant Professor Tomoaki Nishiyama, Center for Disease Model Research, Kanazawa University The joint research team identified the genes that determine the mating type of the mating algae (Fig. 1). did.
Furthermore, using the Himemikazukimo genome editing technology established by this group, we showed that this gene is the body of the gene that determines the mating type.
This gene is thought to have evolved from a gene important for sexual reproduction in land plants to a mating type determination gene. In addition, the algae are one of the most closely related algae to terrestrial plants (Fig. 2). It is expected to contribute to the elucidation.
The results of this research were published in the online version of the British scientific journal “New Phytologist”.
【background】
In many organisms, males and females are genetically determined, and sexual reproduction takes place between them. In the unicellular algae called Himemikazukimo, which is closely related to terrestrial plants, it is known that there are also two types of sexes, and that sexual reproduction occurs only between different types. Males and females are distinguished by focusing on the production of germ cells of different sizes, such as sperm and eggs. This is called a junction type. The mechanism that determines the mating type has been elucidated only in a limited number of organisms.
So far, this joint research team has established and published technologies for foreign gene transfer (*2) and genome editing (*3) into the genus Abe et al. 2011, 2016, while proceeding with genome sequencing. Kanda et al. 2017, Kawai et al. 2022).
[Image 1
Figure 1. Vegetative cells and zygotes of Pleurotus spp. When two Pleurotus spp. (left) with different mating types are mixed under appropriate conditions, they meet and fuse to form zygotes (right). [Image 2
Figure 2. Phylogenetic relationship between zygomatic algae and terrestrial plants The zygomatic algae, including zygomatic algae, are the most closely related group of terrestrial plants.
[Results of this research]
Outline genome sequences (approximately 360 million base pairs and 340 million base pairs) of two phylogenetic strains (NIES-67: + type, NIES-68: – type) corresponding to two mating types ), identified a sequence (a region of about 2 million base pairs) that was inherited in the -type offspring but not in the +type offspring, and found a candidate gene in the -type genome, named CpMinus1. I was. When this gene is introduced into the NIES-67 strain (+ type), it behaves as a – type, such as conjugating with NIES-67 (+ type) but not NIES-68 (- type). It was found that when CpMinus1 in 68 strains was disrupted by genome editing technology, it behaved as a + type (Fig. 3). From this, we found that CpMinus1 is a gene that almost exclusively determines mating type (Fig. 4).
CpMinus1 is thought to have been derived independently as a mating type-determining gene in asexual mating algae from the RKD(A) gene family, which shows an important role in the sexual reproduction process of land plants. In addition, it is thought that the mating type determinant (MID) of Chlamydomonas came to control the
determination of mating type independently.
[Image 3
Figure 3. Experimental verification that CpMinus1 is a sex-determining factor When the CpMinus1 gene is introduced into the chromosome of +-type cells, they behave as –type cells (= mating with +-type cells; not mating with –type cells).
When the CpMinus1 gene of -type cells is disrupted, they behave as +type cells (= do not mate with +type cells; mate with -type cells). [Image 4
Figure 4. Mechanism of sex determination
In -type cells, expression of CpMinus1, a -type-specific gene, produces CpMinus1 protein (M1 in the figure), gene group necessary for differentiation into -type (-type differentiation gene group in the figure) ) is induced. It is thought that the induced genes include those encoding proteins (X in the figure) that suppress the gene group necessary for + type differentiation (+ type differentiation gene group in the figure). and the influence of X suppresses the
differentiation into the + type. Since CpMinus1 does not exist in +-type cells, −-type differentiation genes are not expressed, and the expression of +-type differentiation genes is not suppressed. AAA indicates mRNA transcribed from the gene.
[Significance of this research]
In recent years, it has become relatively easy to obtain the genome information of various organisms, and in the field of plants as well, evolutionary developmental research on how plants evolved from their ancestral algae to the evolution of their genomes to land on land. is attracting attention. To date, among green algae, zygotes have been suggested to be the most closely related group to land plants, and the genome sequencing of several zygotes has been reported. However, zygotic algae whose genome information has been reported so far cannot introduce foreign genes or edit their genomes. could not confirm the role of the gene. Furthermore, the genomes of mating algae whose genomes have been examined so far have not been analyzed with a focus on the sexual reproduction phenomenon of mating, and it is completely clear how the mating type, which corresponds to the sex of the gametes, is determined. It wasn’t.
It is the only algae that can be genome-edited among algae that are closely related to land plants. It can be analyzed directly. The results of this research will provide important information not only for the physiology and evolutionary development of plants, but also for the study of plant physiology and evolution.
本研究は、日本学術振興会 科学研究費助成事業（20017013, 23770277, 24247042, 24370038, 25304012, 26440223, 26650147, 15H05237, 16H02518, 16H04836, 16H06378, 18H06367, 18K19365, 19K06827, 19K22446, 19K22448, 20K21451, 21H02549, 22H05177).
In addition, it was supported by the Ministry of Education, Culture, Sports, Science and Technology Grants-in-Aid for Scientific Research on Innovative Areas Genome Support (221S0002) and Advanced Genome Support (16H06279 PAGS). Furthermore, research was conducted using the supercomputer system service of the National Institute of Genetics and the biological information analysis system of the National Institute for Basic Biology.
[Published article bibliographic information]
Paper title: A divergent RWP-RK transcription factor determines mating type in heterothallic Closterium
Authors: Hiroyuki Sekimoto, Ayumi Komiya, Natsumi Tsuyuki, Junko Kawai, Naho Kanda, Ryo Ootsuki, Yutaka Suzuki, Atsushi Toyoda, AsaoFujiyama, Masahiro Kasahara, Jun Abe, Yuki Tsuchikane, Tomoaki Nishiyama
Publication journal: New Phytologist (IF = 10.323)
[Glossary]
*1 Mating type: When mating occurs between two genetically different gametes but they are morphologically indistinguishable, it is assumed that there is a genotype according to the combination of whether they can mate with each other. are called junction types.
*2 Foreign gene introduction: The introduction of DNA that does not originally exist in the organism, or DNA that has been modified in sequence, into the nucleus. In this study, DNA was physically delivered into cells using a “gene gun.”
*3 Genome editing: A technology that selectively modifies specific DNA sequences within the genome. Here, we used the CRISPR/Cas9 system to cut a specific DNA sequence, and used the phenomenon of a sequence that differs from the original when repaired to create a mutation that destroys the function of the gene.
[Inquiries regarding the content of this research]
Professor, Department of Chemistry and Life Science, Faculty of Science, Japan Women’s University
Hiroyuki Sekimoto
TEL: 03-5981-3674
Email: sekimoto@fc.jwu.ac.jp
[About New Phytologist]
New Phytologist is a leading international journal focusing on high quality, original research across the broad spectrum of plant sciences, from intracellular processes through to global environmental change. the promotion of plant science.
https://www.newphytologist.org/
Page of this research: https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.18662 Japan Women’s University was founded as Japan’s first systematic institution of higher education for women, and celebrated its 120th anniversary last year. It is the only private women’s university with a faculty of science, and is a comprehensive women’s university with an educational environment that integrates the humanities and sciences. Through integrated education from kindergarten to graduate school, and recurrent education that is open to non-graduates, we provide opportunities for everyone to learn throughout their lives and create a society that continues to grow. We are cultivating human resources who can create a new tomorrow together in a diverse and discontinuous society. For more information, please visit
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