Sequence of an S-protein of Lycopersicon peruvianum and comparison with other solanaceous S-proteins

Tsai, De Sheng; Lee, H. S.; Post, Laura; Kreiling, K. M.; Kao, Teh Hui

doi:10.1007/bf00197375

Cited by 65 publications

(54 citation statements)

References 35 publications

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“…Michelmore, unpubl.). Accumulation of amino acid changes over long periods of time has been proposed as the mechanism for evolution of gametophytic S-allele specificities (Tsai et al 1992). …”

Section: Clusters Of Resistance Genes Genome Research 1121mentioning

confidence: 99%

Clusters of Resistance Genes in Plants Evolve by Divergent Selection and a Birth-and-Death Process

1998

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Classical genetic and molecular data show that genes determining disease resistance in plants are frequently clustered in the genome. Genes for resistance (R genes) to diverse pathogens cloned from several species encode proteins that have motifs in common. These motifs indicate that R genes are part of signal-transduction systems. Most of these R genes encode a leucine-rich repeat (LRR) region. Sequences encoding putative solvent-exposed residues in this region are hypervariable and have elevated ratios of nonsynonymous to synonymous substitutions; this suggests that they have evolved to detect variation in pathogen-derived ligands. Generation of new resistance specificities previously had been thought to involve frequent unequal crossing-over and gene conversions. However, comparisons between resistance haplotypes reveal that orthologs are more similar than paralogs implying a low rate of sequence homogenization from unequal crossing-over and gene conversion. We propose a new model adapted and expanded from one proposed for the evolution of vertebrate major histocompatibility complex and immunoglobulin gene families. Our model emphasizes divergent selection acting on arrays of solvent-exposed residues in the LRR resulting in evolution of individual R genes within a haplotype. Intergenic unequal crossing-over and gene conversions are important but are not the primary mechanisms generating variation.Plants, like animals, are continually challenged by a myriad of potential pathogens. There is increasing evidence that defense systems of plants are at least as complex as vertebrate defense systems. Unlike animals, however, plants do not have a circulatory system and therefore cannot rely on a specialized, proliferative immune system. Each plant cell has to be capable of defense, even though this defense is coordinated locally and systemically between cells. There are a variety of types of resistance genes and mechanisms, some induced and some constitutive (for review, see Godiard et al. 1994;Michelmore 1995;Hammond-Kosack and Jones 1997). Often, although not always, disease resistance in plants is determined by single, usually dominant, genes. The recent cloning of several such resistance genes (R genes) is providing insight into their function and evolution. The defense system of plants may be ancient and predate the evolution of the immune system; genes similar to plant R genes have been identified in mammals van der Biezen and Jones 1998).In this review we consider what is known about the genomic organization and evolution of disease resistance genes in plants. The picture that is emerging for the organization and evolution of plant R genes is similar to that of the vertebrate major histocompatibility complex (MHC), T-cell receptor (TCR), and immunoglobulin genes. Therefore, although the specific types of genes involved are different, the evolutionary forces shaping the plant and vertebrate defense systems may be similar. We propose a model for the evolution of plant R genes that is adapted and expanded from a m...

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Section: Clusters Of Resistance Genes Genome Research 1121mentioning

confidence: 99%

Clusters of Resistance Genes in Plants Evolve by Divergent Selection and a Birth-and-Death Process

1998

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“…Sequence comparisons of solanaceous S-proteins have revealed five conserved regions and two hypervariable regions (Ioerger et al, 1991;Tsai et al, 1992). The presence of distinct conserved regions has made it possible to clone genomic and cDNA fragments for S-proteins by PCR.…”

Section: Female Specificity Determinant: the S-rnase Genementioning

confidence: 99%

“…For example, the two most divergent solanaceous S-RNases share only 38% sequence identity (Tsai et al, 1992). There are a large number of variable sites scattered throughout the protein; however, the most highly variable sites are clustered in two regions, named HVa and HVb.…”

Section: S-allele-specificity Determinant Of S-rnasesmentioning

confidence: 99%

“…There are a large number of variable sites scattered throughout the protein; however, the most highly variable sites are clustered in two regions, named HVa and HVb. These two hypervariable regions were identified initially from comparison of solanaceous S-RNases (Ioerger et al, 1991;Tsai et al, 1992). They were found subsequently to be the hypervariable regions of Antirrhinum S-RNases as well (Xue et al, 1996) and to correspond to two of the four regions of rosaceous S-RNases for which evidence of positive selection has been found (Ishimizu et al, 1998).…”

Section: S-allele-specificity Determinant Of S-rnasesmentioning

confidence: 99%

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The Molecular and Genetic Bases of S-RNase-Based Self-Incompatibility

Kao

Tsukamoto

2004

THE PLANT CELL ONLINE

248

185

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“…The primers used corresponded to two of the conserved regions of solanaceous S-RNases, C2 (NFTIHGLWP), and C5 (ELNEIGICF; Tsai et al, 1992;Tsukamoto et al, 2003). An approximately 430-bp fragment of the expected size was obtained from all three plants.…”

Section: Isolation Of Full-length Cdna Clones Encoding S C1 - S C2 -mentioning

confidence: 99%

Breakdown of Self-Incompatibility in a Natural Population ofPetunia axillaris Caused by Loss of Pollen Function

et al. 2003

Self Cite

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Although Petunia axillaris subsp. axillaris is described as a self-incompatible taxon, some of the natural populations we have identified in Uruguay are composed of both self-incompatible and self-compatible plants. Here, we studied the selfincompatibility (SI) behavior of 50 plants derived from such a mixed population, designated U83, and examined the cause of the breakdown of SI. Thirteen plants were found to be self-incompatible, and the other 37 were found to be selfcompatible. A total of 14 S-haplotypes were represented in these 50 plants, including two that we had previously identified from another mixed population, designated U1. All the 37 self-compatible plants carried either an S C1 -or an S C2 -haplotype. S C1 S C1 and S C2 S C2 homozygotes were generated by self-pollination of two of the self-compatible plants, and they were reciprocally crossed with 40 self-incompatible S-homozygotes (S 1 S 1 through S 40 S 40 ) generated from plants identified from three mixed populations, including U83. The S C1 S C1 homozygote was reciprocally compatible with all the genotypes examined. The S C2 S C2 homozygote accepted pollen from all but the S 17 S 17 homozygote (identified from the U1 population), but the S 17 S 17 homozygote accepted pollen from the S C2 S C2 homozygote. cDNAs encoding S C2 -and S 17 -RNases were cloned and sequenced, and their nucleotide sequences were completely identical. Analysis of bud-selfed progeny of heterozygotes carrying S C1 or S C2 showed that the SI behavior of S C1 and S C2 was identical to that of S C1 and S C2 homozygotes, respectively. All these results taken together suggested that the S C2 -haplotype was a mutant form of the S 17 -haplotype, with the defect lying in the pollen function. The possible nature of the mutation is discussed.Naturally occurring or induced (e.g. by radiation) self-compatible mutants of self-incompatible species in the Solanaceae have provided useful materials for studying the mechanism of the S-RNase-mediated self-incompatibility (SI) system. For example, molecular genetic studies of a self-compatible line of Lycopersicon peruvianum have suggested that the RNase activity of S-RNases is an integral part of the SI mechanism because mutations in the S-RNase gene rendering its protein product without the RNase activity cause the breakdown of SI (Kowyama et al., 1994a;Royo et al., 1994). Moreover, cytological and molecular genetic studies of x-ray irradiationinduced self-compatible mutants have uncovered a phenomenon, called competitive interaction, where duplication of the S-locus region renders pollen grains carrying two different pollen S-alleles unable to function in SI (de Nettancourt, 1977;Golz et al., 2000). Studies of self-compatible mutants have also led to the identification of loci unlinked to the S-locus that are required for the function of the S-RNase gene or the yet unidentified pollen S-gene. For example, mutations in the HT gene, which encodes a small Asn-rich protein (McClure et al., 1999), are partially responsible for the breakdown o...

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Sequence of an S-protein of Lycopersicon peruvianum and comparison with other solanaceous S-proteins

Cited by 65 publications

References 35 publications

Clusters of Resistance Genes in Plants Evolve by Divergent Selection and a Birth-and-Death Process

Clusters of Resistance Genes in Plants Evolve by Divergent Selection and a Birth-and-Death Process

The Molecular and Genetic Bases of S-RNase-Based Self-Incompatibility

Breakdown of Self-Incompatibility in a Natural Population ofPetunia axillaris Caused by Loss of Pollen Function

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