Highly divergent sequences of the pollen self‐incompatibility (S) gene in class‐I S haplotypes of Brassica campestris (syn. rapa) L

Watanabe, Masao; Ito, Akiko; Takada, Yukyo; Ninomiya, Chie; Kakizaki, Tomohiro; Takahata, Yoshihito; Hatakeyama, Katsunori; Hinata, Kokichi; Suzuki, Go; Takasaki, Takeshi; Satta, Yoko; Shiba, Hiroshi; Takayama, Seiji; Isogai, Akira

doi:10.1016/s0014-5793(00)01514-3

Cited by 111 publications

(79 citation statements)

References 38 publications

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“…Both SRK and SCR exhibit an extraordinarily high degree of DNA and protein sequence variability. Furthermore, the number of S locus variants, or S haplotypes, and consequently of SRK and SCR alleles, is typically large, with as many as 100 S haplotypes occurring in one species (9), and these polymorphisms are estimated to be at least 20-40 million years old (10). These features are consistent with the expectation that new SI variants have a strong reproductive advantage and persist in populations for long periods.…”

supporting

confidence: 53%

Specificity determinants and diversification of the Brassica self-incompatibility pollen ligand

Chookajorn

Kachroo

Ripoll

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

119

114

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Self-incompatibility in crucifers is effected by allele-specific interactions between the highly polymorphic stigmatic S locus receptor kinase (SRK) and its pollen ligand, the S locus cysteine-rich protein (SCR). Here we show that specificity in SCR function is determined by four contiguous amino acids in one variant, indicating that the minimum sequence requirement for gaining a new specificity can be low. We also provide evidence for an extraordinarily high degree of evolutionary flexibility in SCR, whereby SCR can tolerate extensive amino acid changes within the limits of maintaining the same predicted overall structure. This remarkable adaptability suggests a hypothesis for generation of new self-incompatibility specificities by gradual modification of SRK-SCR affinities and, more generally, for functional specialization within families of homologous ligands and receptors. In the self-incompatibility (SI) response of crucifers, the recognition of self-related pollen by the stigma epidermis is effected through the activity of two tightly linked and highly polymorphic genes encoded by the S locus (1). The S locus receptor kinase gene SRK encodes a single-pass transmembrane serine͞threonine kinase (2), which is an integral component of the plasma membrane of the stigma epidermis (3-5) and is displayed with its glycosylated N-terminal S domain external to the cell (6). The S locus cysteinerich protein gene SCR (7) [also designated SP-11 (8)] encodes a small (Ͻ8 kDa) hydrophilic and positively charged peptide that is localized to the pollen coat. Both SRK and SCR exhibit an extraordinarily high degree of DNA and protein sequence variability. Furthermore, the number of S locus variants, or S haplotypes, and consequently of SRK and SCR alleles, is typically large, with as many as 100 S haplotypes occurring in one species (9), and these polymorphisms are estimated to be at least 20-40 million years old (10). These features are consistent with the expectation that new SI variants have a strong reproductive advantage and persist in populations for long periods.Recent studies have shown that SCR is a ligand for SRK (11, 12) and that specificity in the SI response is determined by allelespecific interactions between the SRK receptor and the SCR ligand (11). In a self-pollination, the SCR protein delivered to the stigma binds to the ectodomain of its cognate ''self'' SRK and activates the SRK kinase. In turn, this activation presumably triggers a signal transduction pathway that results in the inhibition of pollen hydration, germination, and pollen tube penetration into the stigma epidermal cell wall. In contrast, in a cross-pollination, pollen tube growth proceeds unimpeded because the SCR variant that is delivered to the stigma by the pollen coat cannot bind nor activate ''non-self'' SRK. An implication of this model is that the SRK and SCR genes must coevolve to maintain their interaction. Thus, in this two-gene system, the generation of a novel SI specificity requires the occurrence of compensatory mutations in recep...

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supporting

confidence: 53%

Specificity determinants and diversification of the Brassica self-incompatibility pollen ligand

Chookajorn

Kachroo

Ripoll

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

119

114

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“…Some of our DEFL genes could be involved in reproductive regulation as are members of the stig1 gene family (Goldman et al, 1994), or the Sterility-locus (S-locus) Cys-rich (SCR; Schopfer et al, 1999) and related pollen coat proteins (Watanabe et al, 2000). Beginning with the male determinant of sporophytic self-incompatibility (SSI), SP11 (a SCR protein), Vanoosthuyse et al (2001) used iterative BLAST searches to discover 37% of the peptides we identified.…”

Section: Defls May Have Functions Unrelated To Defensementioning

confidence: 99%

“…Beginning with the male determinant of sporophytic self-incompatibility (SSI), SP11 (a SCR protein), Vanoosthuyse et al (2001) used iterative BLAST searches to discover 37% of the peptides we identified. SP11 adopts the same three-dimensional fold as many defensins (Chookajorn et al, 2004) and displays high levels of divergent selection and allelic diversity (Watanabe et al, 2000). Binding of SP11 from selfpollen to the stigma-specific S-locus receptor kinase (SLK) starts the cascade of responses that leads to rejection.…”

Section: Defls May Have Functions Unrelated To Defensementioning

confidence: 99%

Genome Organization of More Than 300 Defensin-Like Genes in Arabidopsis

et al. 2005

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Defensins represent an ancient and diverse set of small, cysteine-rich, antimicrobial peptides in mammals, insects, and plants. According to published accounts, most species' genomes contain 15 to 50 defensins. Starting with a set of largely nodulespecific defensin-like sequences (DEFLs) from the model legume Medicago truncatula, we built motif models to search the nearcomplete Arabidopsis (Arabidopsis thaliana) genome. We identified 317 DEFLs, yet 80% were unannotated at The Arabidopsis Information Resource and had no prior evidence of expression. We demonstrate that many of these DEFL genes are clustered in the Arabidopsis genome and that individual clusters have evolved from successive rounds of gene duplication and divergent or purifying selection. Sequencing reverse transcription-PCR products from five DEFL clusters confirmed our gene predictions and verified expression. For four of the largest clusters of DEFLs, we present the first evidence of expression, most frequently in floral tissues. To determine the abundance of DEFLs in other plant families, we used our motif models to search The Institute for Genomic Research's gene indices and identified approximately 1,100 DEFLs. These expressed DEFLs were found mostly in reproductive tissues, consistent with our reverse transcription-PCR results. Sequence-based clustering of all identified DEFLs revealed separate tissue-or taxon-specific subgroups. Previously, we and others showed that more than 300 DEFL genes were expressed in M. truncatula nodules, organs not present in most plants. We have used this information to annotate the Arabidopsis genome and now provide evidence of a large DEFL superfamily present in expressed tissues of all sequenced plants.Organisms are constantly confronted with potentially pathogenic microorganisms. Yet, few encounters result in disease, due to the multilayered lines of defense each organism possesses. In vertebrates, adaptive immunity has long held center stage because of its ability to recognize almost any foreign antigen. The ancient innate immune system is equally important and provides a critical line of defense in vertebrates, invertebrates, plants, and insects (Thomma et al., 2002;Beutler, 2004;Bulet et al., 2004;Finlay and Hancock, 2004).In plants, innate immunity occurs via elaborate mechanisms (Dangl and Jones, 2001;Veronese et al., 2003). The plant cell wall serves as a barrier to microbial penetration. Antimicrobial compounds deter would-be invaders. Should penetration occur, recognition leads to the production of reactive oxygen intermediates, cell wall strengthening, activation of protein kinase pathways, and the production of signaling intermediates. Signaling events lead to localized responses such as a hypersensitive response (programmed cell death) or to the release of antimicrobial compounds. The plant is also immunized against unrelated pathogens via systemic acquired resistance (Delaney, 1997;Dong, 2001;Gozzo, 2003).Much attention has focused on the interaction of plant resistance genes (R-genes) and pathoge...

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“…These cDNA clones were encoding genes related to secondary metabolism (Group 2: chalcone synthase, Group 9: flavonone-3-hydroxylase), transcription (Group 517: Myb26 protein, Group 554: MADS-box protein, GDEF1, Group 606: MADS box 26 protein), signal transduction (Group 642: protein kinase), hypothetical protein (Group 6, Group 16) and human disease associated protein (Group 170: cleft lip and palate associated transmembrane protein-like protein). In order to perform RT-PCR analysis, mRNA isolated from anthers from mature flower buds, anthers from immature flower buds, pistils from mature flower buds, pistils from immature flower buds, and leaves were reverse-transcribed by using the First-Strand cDNA synthesis kit (Amersham-Pharmacia, Uppsala, Sweden), as described in Watanabe et al (2000). The first strand cDNA was then used as a template for PCR amplification with a set of primers, Not I-dT and a specific primer to each gene.…”

mentioning

confidence: 99%

Generation of 919 expressed sequence tags from immature flower buds and gene expression analysis using expressed sequence tags in the model plant Lotus japonicus.

et al. 2002

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Lotus japonicus has received increased attention as a potential model legume plant. In order to study gene expression in reproductive organs and to identify genes that play a crucial function in sexual reproduction, we constructed a cDNA library from immature flower buds containing anthers at the stage of developing tapetum cells in L. japonicus , and characterized 919 expressed sequence tags (ESTs) randomly selected from a cDNA library of the immature flower buds. The 919 ESTs analyzed were clustered into 821 non-redundant EST groups. As a result of a database search, 436 groups (53%) out of the 821 groups showed sequence similarity to genes registered in the public database. Out of these 436 groups, 109 groups showed similarity to genes encoding hypothetical proteins whose function had not yet been estimated. Three hundred eighty five groups (47%) showed no significant homology to known sequences and were classified as novel sequences. A comparison of 821 non-redundant EST sequences and EST sequences derived from the whole plant L. japonicus revealed that 474 EST sequences derived from immature flower buds were not found in the EST sequences of the whole plant. In order to confirm the expression pattern of potential reproductive-organ specific EST clones, nine clones, which were not matched to ESTs derived from the whole plant, were selected, and RT-PCR analysis was performed on these clones. As a result of RT-PCR, we found two novel anther specific clones. One clone was homologous to a gene encoding human cleft lip and palate associated transmembrane protein (CLPTM1) like protein, and the other clone did not show a significant similarity to any genes deposited in the public database. These results indicate that ESTs analyzed here represent a valuable resource for finding reproductive-organ specific genes in Lotus japonicus .Large-scale random sequencing of cDNA has provided a large amount of information for gene identification during genome research. This kind of information could help to identify genes expressed in a particular tissue or under a specific condition and to understand the complexity of gene expression. Expressed sequence tags (ESTs) analysis focusing on guard cells in Brassica campestris (Kwark et al., 1997), roots in B. napus (Park et al., 1993), wood forming tissues in poplars (Sterky et al., 1998) and female sexual organs in liverworts (Nagai et al., 1999) have revealed tissue specific transcripts or gene expression patterns.The developmental programs of the male and female organs are substantially independent of each other and of vegetative plants. It is of great interest to discover the underlying molecular mechanisms that control the development of the stamen and pistil and the interaction between the pollen and pistil. In the late developmental

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Highly divergent sequences of the pollen self‐incompatibility (S) gene in class‐I S haplotypes of Brassica campestris (syn. rapa) L

Cited by 111 publications

References 38 publications

Specificity determinants and diversification of the Brassica self-incompatibility pollen ligand

Specificity determinants and diversification of the Brassica self-incompatibility pollen ligand

Genome Organization of More Than 300 Defensin-Like Genes in Arabidopsis

Generation of 919 expressed sequence tags from immature flower buds and gene expression analysis using expressed sequence tags in the model plant Lotus japonicus.

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