ゼツアツ コウトウ ウンドウ ケイソク システム ニ ヨル パーキンソンビョウ カンジャ ノ エンゲ ドウタイ ヒョウカ

The different forms of flowers in a species have attracted the attention of many evolutionary biologists, including Charles Darwin. In Fagopyrum esculentum (common buckwheat), the occurrence of dimorphic flowers, namely short-styled and long-styled flowers, is associated with a type of self-incompatibility (SI) called heteromorphic SI. The floral morphology and intra-morph incompatibility are both determined by a single genetic locus named the S-locus. Plants with short-styled flowers are heterozygous (S/s) and plants with long-styled flowers are homozygous recessive (s/s) at the S-locus. Despite recent progress in our understanding of the molecular basis of flower development and plant SI systems, the molecular mechanisms underlying heteromorphic SI remain unresolved. By examining differentially expressed genes from the styles of the two floral morphs, we identified a gene that is expressed only in short-styled plants. The novel gene identified was completely linked to the S-locus in a linkage analysis of 1,373 plants and had homology to EARLY FLOWERING 3. We named this gene S-LOCUS EARLY FLOWERING 3 (S-ELF3). In an ion-beam-induced mutant that harbored a deletion in the genomic region spanning S-ELF3, a phenotype shift from short-styled flowers to long-styled flowers was observed. Furthermore, S-ELF3 was present in the genome of short-styled plants and absent from that of long-styled plants both in world-wide landraces of buckwheat and in two distantly related Fagopyrum species that exhibit heteromorphic SI. Moreover, independent disruptions of S-ELF3 were detected in a recently emerged self-compatible Fagopyrum species and a self-compatible line of buckwheat. The nonessential role of S-ELF3 in the survival of individuals and the prolonged evolutionary presence only in the genomes of short-styled plants exhibiting heteromorphic SI suggests that S-ELF3 is a suitable candidate gene for the control of the short-styled phenotype of buckwheat plants

Assembly of the draft genome of buckwheat and its applications in identifying agronomically useful genes.

世界初となるソバの全ゲノム解読に成功 －ソバの安全性、高品質性、収量安定性の鍵となる遺伝情報の発見－. 京都大学プレスリリース. 2016-04-13.Buckwheat (Fagopyrum esculentumMoench; 2n= 2x= 16) is a nutritionally dense annual crop widely grown in temperate zones. To accelerate molecular breeding programmes of this important crop, we generated a draft assembly of the buckwheat genome using short reads obtained by next-generation sequencing (NGS), and constructed the Buckwheat Genome DataBase. After assembling short reads, we determined 387, 594 scaffolds as the draft genome sequence (FES_r1.0). The total length of FES_r1.0 was 1, 177, 687, 305 bp, and the N50 of the scaffolds was 25, 109 bp. Gene prediction analysis revealed 286, 768 coding sequences (CDSs; FES_r1.0_cds) including those related to transposable elements. The total length of FES_r1.0_cds was 212, 917, 911 bp, and the N50 was 1, 101 bp. Of these, the functions of 35, 816 CDSs excluding those for transposable elements were annotated by BLAST analysis. To demonstrate the utility of the database, we conducted several test analyses using BLAST and keyword searches. Furthermore, we used the draft genome as a reference sequence for NGS-based markers, and successfully identified novel candidate genes controlling heteromorphic self-incompatibility of buckwheat. The database and draft genome sequence provide a valuable resource that can be used in efforts to develop buckwheat cultivars with superior agronomic traits

S-LOCUS EARLY FLOWERING 3 is exclusively present in the genomes of short-styled buckwheat plants that exhibit heteromorphic self-incompatibility.

The different forms of flowers in a species have attracted the attention of many evolutionary biologists, including Charles Darwin. In Fagopyrum esculentum (common buckwheat), the occurrence of dimorphic flowers, namely short-styled and long-styled flowers, is associated with a type of self-incompatibility (SI) called heteromorphic SI. The floral morphology and intra-morph incompatibility are both determined by a single genetic locus named the S-locus. Plants with short-styled flowers are heterozygous (S/s) and plants with long-styled flowers are homozygous recessive (s/s) at the S-locus. Despite recent progress in our understanding of the molecular basis of flower development and plant SI systems, the molecular mechanisms underlying heteromorphic SI remain unresolved. By examining differentially expressed genes from the styles of the two floral morphs, we identified a gene that is expressed only in short-styled plants. The novel gene identified was completely linked to the S-locus in a linkage analysis of 1,373 plants and had homology to EARLY FLOWERING 3. We named this gene S-LOCUS EARLY FLOWERING 3 (S-ELF3). In an ion-beam-induced mutant that harbored a deletion in the genomic region spanning S-ELF3, a phenotype shift from short-styled flowers to long-styled flowers was observed. Furthermore, S-ELF3 was present in the genome of short-styled plants and absent from that of long-styled plants both in world-wide landraces of buckwheat and in two distantly related Fagopyrum species that exhibit heteromorphic SI. Moreover, independent disruptions of S-ELF3 were detected in a recently emerged self-compatible Fagopyrum species and a self-compatible line of buckwheat. The nonessential role of S-ELF3 in the survival of individuals and the prolonged evolutionary presence only in the genomes of short-styled plants exhibiting heteromorphic SI suggests that S-ELF3 is a suitable candidate gene for the control of the short-styled phenotype of buckwheat plants

PCR survey of <i>S-ELF3</i> (<i>SSG3</i>) in 47 buckwheat landraces and modern cultivars.

<p>The numbering of individual plants corresponds to that shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031264#pone.0031264.s008" target="_blank">Table S2</a>. L, long-styled plant. S, short-styled plant. N, negative control. M, 1-kb DNA ladder (GenDireX).</p

Dimorphic flowers of buckwheat and schematic presentation of the intra-morph incompatibility response in buckwheat.

<p>Short-styled flowers of buckwheat have long stamens and vice versa. A pollen grain from a long-styled plant germinates and the pollen tube successfully elongates to reach the ovary in the pistil of a short-styled plant, whereas it germinates but fails to elongate in the style of long-styled flower.</p

Expression of genes selected by in <i>silico</i> subtraction as determined by RT-PCR.

<p>The expression of genes corresponding to the 15 contigs selected by <i>in silico</i> subtraction was examined by RT-PCR using cDNA from long styles (LS) and short styles (SS) as templates. See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031264#pone.0031264.s007" target="_blank">Table S1</a> for RT-PCR primers.</p

<i>S-ELF3</i> in <i>Fagopyrum</i> species.

<p>The gene structure and phylogeny of <i>S-ELF3</i> in five <i>Fagopyrum</i> species, including the SC Kyushu PL4 line, which contains the <i>S^h</i> allele of <i>F. homotropicum</i>, are shown. Species in blue and red font exhibit heteromorphic SI and homomorphic SC, respectively. Dark brown boxes and lines represent 5′- and 3′-untranslated regions and introns, respectively. Coding regions are colored blue. Red boxes and line indicate large insertions (>400 bp) and nonsense mutation, respectively. The phylogenetic tree in the inset was obtained by the Neighbor-joining method. The <i>S-ELF3</i> sequence from <i>F. urophyllum</i> was used as an outgroup. The bootstrap numbers (500 replicates) are shown next to the branches. The scale bar corresponds to 0.02 substitution per nucleotide site.</p

Expression analysis of <i>S-ELF3</i> transcripts.

<p>cDNA prepared from roots, stems, leaves, pistils, stamens and pollen was used for RT-PCR analysis. <i>ACTIN</i> was amplified as a loading control. DBF: one day before flowering. DF: the day of flowering.</p