A Toxic Mutator and Selection Alternative to the Non-Mendelian RNA Cache Hypothesis for <i>hothead</i> Reversion

Comai, Luca; Cartwright, Reed A.

doi:10.1105/tpc.105.036293

Cited by 18 publications

(18 citation statements)

References 20 publications

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“…Lolle et al (2005) suggested that RNAs synthesized by the parent may be stored in plants of subsequent generations that do not carry the corresponding genomic information and that these RNAs may be used as a template to restore the genomic information carried by the previous generation. Four alternative hypotheses have been proposed to account for this nonMendelian behavior: two of them are also based on template-directed gene conversion (Chaudhury 2005;Ray 2005), the third one appeals to a process of mutation accumulation followed by selection (Comai and Cartwright 2005;Henikoff 2005), and the fourth one involves chimerism (Krishnaswamy and Peterson 2007). However, Peng et al (2006) reported that hth mutant shows a tendency toward outcrossing and recover a normal genetic behavior when grown in isolation.…”

mentioning

confidence: 99%

Outcrossing as an Explanation of the Apparent Unconventional Genetic Behavior ofArabidopsis thaliana hthMutants

Mercier¹,

Jolivet²,

Vignard³

et al. 2008

Genetics

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The reappearance of HTH alleles in the offspring of homozygous Arabidopsis hth mutants is not consistent with classical Mendelian genetics. It has been suggested that stored RNA may be used to restore genetic information. However, Peng et al. reported that hth mutants tend to display outcrossing and suggested that outcrossing might provide an alternative explanation for the apparent genetic instability. We have confirmed and extended these results, corroborating that the apparent non-Mendelian behavior of hth mutants can be explained by their susceptibility to outcrossing.

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mentioning

confidence: 99%

Outcrossing as an Explanation of the Apparent Unconventional Genetic Behavior ofArabidopsis thaliana hthMutants

Mercier¹,

Jolivet²,

Vignard³

et al. 2008

Genetics

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“…One possibility is that the high-frequency phenotypic suppression in EMS-treated bal plants results from the selection within the meristematic tissues that favors cells carrying a mutation in SNC1 (Comai and Cartwright 2005;Henikoff 2005). Constitutive activation of RPP5 locus R genes exacts a significant fitness cost during vegetative growth (Heidel et al 2004).…”

Section: Resultsmentioning

confidence: 99%

Gene Duplication and Hypermutation of the Pathogen Resistance Gene SNC1 in the Arabidopsis bal Variant

Yi¹,

Richards

2009

Genetics

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The bal defect in the Arabidopsis thaliana Columbia strain was spontaneously generated in an inbred ddm1 (decrease in DNA methylation 1) mutant background in which various genetic and epigenetic alterations accumulate. The bal variant displays short stature and curled leaves due to the constitutive activation of defense signaling. These bal phenotypes are metastable and phenotypic suppression is evident in more than one-third of ethyl methanesulfonate (EMS)-treated bal M 1 plants. The semidominant bal allele maps to the RPP5 (recognition of Peronospora parasitica 5) locus, which includes a cluster of disease Resistance (R) genes, many of which show an increase in steady-state expression levels in the bal variant. Here, we report that activation of RPP5 locus R genes and dwarfing in the bal variant are caused by a 55-kb duplication within the RPP5 locus. Although many RPP5 locus R genes are duplicated in the bal variant, the duplication of SNC1 alone is necessary and sufficient for the phenotypic changes in the bal variant. Missense mutations in the SNC1 gene were identified in all three phenotypically suppressed EMS-treated bal lines investigated, indicating that the high-frequency phenotypic instability induced by EMS treatment is caused by a genetic mechanism. We propose that the high degree of variation in SNC1-related sequences among Arabidopsis natural accessions follows the two-step mechanism observed in the bal variant: gene duplication followed by hypermutation.

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“…If no drop is observed, this would contradict the implied dilution of the cache in the parental cross, thus providing a critical genetic test of the model. Comai and Cartwright (2005) propose an alternative to the cache model. They argue that the high rate of unselected mutation in hth/hth plants can be explained if mutations in the hth protein have mutagenic effects.…”

Section: Instability Of Mutations In the Hth Genementioning

confidence: 99%

“…HTH is a member of a plantspecific gene family that includes mandelonitrile lyase (MDL), which releases hydrogen cyanide from the simple aromatic compound, mandelonitrile, causing cyanogenicity. MDL has been purified from several cyanogenic plant sources (Evans, 1996;Comai and Cartwright, 2005). In Prunus tissues, its natural substrates are the O-linked monoglucoside, prunasin, and the diglucoside, amygdalin, of mandelonitrile, which are also found in other plants.…”

Section: The Toxic Mutator and Selection Hypothesismentioning

confidence: 99%

“…b and l DNA polymerases appear to have diverged prior to the plant animal split, with b being lost from the plant lineage. Thus, an excellent candidate for a toxic mutator is a glycosylated mandelonitrile inhibitor of DNA polymerase l. Moreover, plant DNA polymerase l activity is specific for meristematic and meiotic tissues (Uchiyama et al, 2004), so that its inhibition might lead to defective gamete production, a key prediction of the toxic mutator hypothesis (Comai and Cartwright, 2005).…”

Section: Inhibition Of Base Excision Repair Might Account For Hth Revmentioning

confidence: 99%

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Rapid Changes in Plant Genomes

Henikoff

2005

Plant Cell

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A Toxic Mutator and Selection Alternative to the Non-Mendelian RNA Cache Hypothesis for hothead Reversion

Cited by 18 publications

References 20 publications

Outcrossing as an Explanation of the Apparent Unconventional Genetic Behavior ofArabidopsis thaliana hthMutants

Outcrossing as an Explanation of the Apparent Unconventional Genetic Behavior ofArabidopsis thaliana hthMutants

Gene Duplication and Hypermutation of the Pathogen Resistance Gene SNC1 in the Arabidopsis bal Variant

Rapid Changes in Plant Genomes

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