S-alleles are retained and expressed in a self-compatible cultivar of Petunia hybrida

Ai, Yunjun; Kron, Eric; Kao, Teh Hui

doi:10.1007/bf00280291

Cited by 85 publications

(44 citation statements)

References 29 publications

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“…Recombinant SLF proteins bind S-RNases nonspecifically, and SLF expression in transgenic plants results in a loss of SI rather than in the gain of a new S-allele specificity. Since other proteins can bind S-RNases (Sims and Ordanic 2001), and since mutations in other genes can lead to self-compatible phenotypes (e.g., Ai et al 1991), it remains formally possible that the properties currently used to define pollen S in the Solanaceae and Plantaginaceae are not exclusive to this factor.…”

Section: Discussionmentioning

confidence: 99%

Expression of 10 S-Class SLF-like Genes in Nicotiana alata Pollen and Its Implications for Understanding the Pollen Factor of the S Locus

Wheeler

Newbigin

2007

Genetics

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The S locus of Nicotiana alata encodes a polymorphic series of ribonucleases (S-RNases) that determine the self-incompatibility (SI) phenotype of the style. The pollen product of the S locus (pollen S) in N. alata is unknown, but in species from the related genus Petunia and in self-incompatible members of the Plantaginaceae and Rosaceae, this function has been assigned to an F-box protein known as SLF or SFB. Here we describe the identification of 10 genes (designated DD1-10) encoding SLF-related proteins that are expressed in N. alata pollen. Because our approach to cloning the DD genes was based on sequences of SLFs from other species, we presume that one of the DD genes encodes the N. alata SLF ortholog. Seven of the DD genes were exclusively expressed in pollen and a low level of sequence variation was found in alleles of each DD gene. Mapping studies confirmed that all 10 DD genes were linked to the S locus and that at least three were located in the same chromosomal segment as pollen S. Finally, the different topologies of the phylogenetic trees produced using available SLF-related sequences and those produced using S-RNase sequences suggests that pollen S and the S-RNase have different evolutionary histories.

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Section: Discussionmentioning

confidence: 99%

Expression of 10 S-Class SLF-like Genes in Nicotiana alata Pollen and Its Implications for Understanding the Pollen Factor of the S Locus

Wheeler

Newbigin

2007

Genetics

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“…Certainly, single mutations at the S-locus can cause an instantaneous loss of SI (Royo et al, 1994;Golz et al, 2000), but it remains possible that SC can sometimes arise gradually from quantitative SI. Genetic work reveals that both quantitative variation in SI (Levin, 1996;Good-Avilla and Stephenson, 2002) and complete SC (Ai et al, 1991;Tsukamoto et al, 2003) are often governed by modifier loci, rather than by mutations at the S-locus itself. Commonalities between quantitative SI and complete SC have been found at the level of transcription of S-RNases, posttranslational modification of S-RNases, and regulation of the unlinked modifier gene, HT.…”

Section: Discussionmentioning

confidence: 99%

Variation in the self‐incompatibility response within and among populations of the tropical shrub Witheringia solanacea (Solanaceae)

Stone

Sasuclark

Blomberg

2006

American J of Botany

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Breakdown of genetically enforced self-incompatibility (SI), an extremely common and important evolutionary transition in plants, has conventionally been conceived as a qualitative rather than a quantitative change. We evaluated qualitative and quantitative variation in SI for four populations of Witheringia solanacea in Costa Rica, examining growth of self-pollen tubes in pollinations of buds and mature flowers. We also measured levels of RNase production in styles to determine whether enzyme production was correlated with differences in self-rejection. The two small populations contained both self-compatible (SC) individuals and obligate outcrossers (female or SI). Plants in the two large populations were uniformly SI as revealed by pollen tube growth, although several of these individuals sporadically set seed autogamously. Stylar RNase activity did not differ significantly between bud and mature flowers, but self-pollen tube growth did differ, suggesting that a gene product in addition to S-RNase is responsible for developmental onset of SI. Population-level differences in RNase activity were consistent with differences in the strength of the rejection response in bud pollinations, suggesting that a threshold level of S-RNase, in combination with other factors, is necessary for SI. Our results support a growing body of evidence that not only qualitative variation in SI, but also quantitative variation may be functionally significant.

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“…S C1 -RNase was most similar to S 1 -RNase of P. axillaris subsp. axillaris, sharing 53.2% sequence identity (Tsukamoto et al, 2003), and S 17 -RNase was most similar with S X -RNase of Petunia hybrida Vilm., sharing 68.0% sequence identity (Ai et al, 1991). …”

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

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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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S-alleles are retained and expressed in a self-compatible cultivar of Petunia hybrida

Cited by 85 publications

References 29 publications

Expression of 10 S-Class SLF-like Genes in Nicotiana alata Pollen and Its Implications for Understanding the Pollen Factor of the S Locus

Expression of 10 S-Class SLF-like Genes in Nicotiana alata Pollen and Its Implications for Understanding the Pollen Factor of the S Locus

Variation in the self‐incompatibility response within and among populations of the tropical shrub Witheringia solanacea (Solanaceae)

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

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