scholarly journals Ornithine decarboxylase genes contribute to S-RNase-independent pollen rejection

2021 ◽  
Author(s):  
Xiaoqiong Qin ◽  
Roger T Chetelat
Keyword(s):  
Ornithine Decarboxylase ◽  
Transmission Ratio Distortion ◽  
Farnesyl Pyrophosphate ◽  
Loss Of Function ◽  
Solanum Pennellii ◽  
Farnesyl Pyrophosphate Synthase ◽  
Pollen Rejection ◽  
Knockout Mutants ◽  
Ratio Distortion ◽  
Low Levels

Abstract Unilateral incompatibility (UI) manifests as pollen rejection in the pistil, typically when self-incompatible (SI) species are pollinated by self-compatible (SC) relatives. In the Solanaceae, UI occurs when pollen lack resistance to stylar S-RNases, but other, S-RNase-independent mechanisms exist. Pistils of the wild tomato Solanum pennellii LA0716 (SC) lack S-RNase yet reject cultivated tomato (S. lycopersicum, SC) pollen. In this cross, UI results from low pollen expression of a farnesyl pyrophosphate synthase gene (FPS2) in S. lycopersicum. Using pollen from fps2-/- loss-of-function mutants in S. pennellii, we identified a pistil factor locus, ui3.1, required for FPS2-based pollen rejection. We mapped ui3.1 to an interval containing 108 genes situated on the IL 3-3 introgression. This region includes a cluster of ornithine decarboxylase (ODC2) genes, with four copies in S. pennellii, versus one in S. lycopersicum. Expression of ODC2 transcript was 1034-fold higher in S. pennellii than in S. lycopersicum styles. Pistils of odc2-/-knockout mutants in IL 3-3 or S. pennellii fail to reject fps2 pollen and abolish transmission ratio distortion (TRD) associated with FPS2. Pollen of S. lycopersicum express low levels of FPS2 and are compatible on IL 3-3 pistils, but incompatible on IL 12-3 x IL 3-3 hybrids, which express both ODC2 and ui12.1, a locus thought to encode the SI proteins HT-A and HT-B. TRD observed in F2 IL 12-3 x IL 3-3 points to additional ODC2-interacting pollen factors on both chromosomes. Thus, ODC2 genes contribute to S-RNase independent UI and interact genetically with ui12.1 to strengthen pollen rejection.

scholarly journals No evidence for biased co-transmission of speciation islands in Anopheles gambiae

2012 ◽  
Vol 367 (1587) ◽  
pp. 374-384 ◽  
Author(s):  
Matthew W. Hahn ◽  
Bradley J. White ◽  
Christopher D. Muir ◽  
Nora J. Besansky
Keyword(s):  
Gene Flow ◽  
Anopheles Gambiae ◽  
Transmission Ratio Distortion ◽  
Transmission Ratio ◽  
Expected Number ◽  
S Alleles ◽  
Likelihood Model ◽  
Ratio Distortion ◽  
Low Levels ◽  
Genome Scale

Genome-scale scans have revealed highly heterogeneous levels of divergence between closely related taxa in many systems. Generally, a small number of regions show high differentiation, with the rest of the genome showing no or only low levels of divergence. These patterns have been interpreted as evidence for ongoing speciation-with-gene-flow, with introgression homogenizing the whole genome except loci involved in reproductive isolation. However, as the number of selected loci increases, the probability of introgression at unselected loci decreases unless there is a transmission ratio distortion causing an over-representation of specific combinations of alleles. Here we examine the transmission of three ‘speciation islands’ that contain fixed differences between the M and S forms of the mosquito, Anopheles gambiae . We made reciprocal crosses between M and S parents and genotyped over 2000 F 2 individuals, developing a hierarchical likelihood model to identify specific genotypes that are under- or over-represented among the recombinant offspring. Though our overall results did not match the expected number of F 2 genotypes, we found no biased co-transmission among M or S alleles in the three islands. Our likelihood model did identify transmission ratio distortion at two of the three islands, but this distortion was small (approx. 3%) and in opposite directions for the two islands. We discuss how our results impinge on hypotheses of current gene flow between M and S and ongoing speciation-with-gene-flow in this system.

Maternal Transmission Ratio Distortion of GNAS Loss‐of‐Function Mutations

2020 ◽  
Vol 35 (5) ◽  
pp. 913-919 ◽  
Author(s):  
Sarah Snanoudj ◽  
Arnaud Molin ◽  
Cindy Colson ◽  
Nadia Coudray ◽  
Sylvie Paulien ◽  
...  
Keyword(s):  
Transmission Ratio Distortion ◽  
Transmission Ratio ◽  
Loss Of Function ◽  
Maternal Transmission ◽  
Ratio Distortion

Cloning and characterization of Farnesyl pyrophosphate synthase gene from Anoectochilus

2019 ◽  
Vol 52 (3) ◽  
Author(s):  
Lin Yang ◽  
Jun Cheng Zhang ◽  
Wan Chen Li ◽  
Jing Tao Qu ◽  
Hao Qiang Yu ◽  
...  
Keyword(s):  
Farnesyl Pyrophosphate ◽  
Farnesyl Pyrophosphate Synthase

scholarly journals Transmission ratio distortion in the myotonic dystrophy locus in human preimplantation embryos

2006 ◽  
Vol 14 (3) ◽  
pp. 299-306 ◽  
Author(s):  
Nicola L Dean ◽  
J Concepción Loredo-Osti ◽  
T Mary Fujiwara ◽  
Kenneth Morgan ◽  
Seang Lin Tan ◽  
...  
Keyword(s):  
Myotonic Dystrophy ◽  
Transmission Ratio Distortion ◽  
Preimplantation Embryos ◽  
Transmission Ratio ◽  
Ratio Distortion ◽  
Human Preimplantation Embryos

scholarly journals Two Loci Contribute Epistastically to Heterospecific Pollen Rejection, a Postmating Isolating Barrier Between Species

2017 ◽  
Vol 7 (7) ◽  
pp. 2151-2159 ◽  
Author(s):  
Jennafer A P Hamlin ◽  
Natasha A Sherman ◽  
Leonie C Moyle
Keyword(s):  
Female Choice ◽  
Genetic Basis ◽  
Reproductive Tract ◽  
Interspecific Cross ◽  
Solanum Species ◽  
Female Reproductive Tract ◽  
Solanum Pennellii ◽  
Heterospecific Pollen ◽  
Male Gametes ◽  
Pollen Rejection

Abstract Recognition and rejection of heterospecific male gametes occurs in a broad range of taxa, although the complexity of mechanisms underlying these components of postmating cryptic female choice is poorly understood. In plants, the arena for postmating interactions is the female reproductive tract (pistil), within which heterospecific pollen tube growth can be arrested via active molecular recognition and rejection. Unilateral incompatibility (UI) is one such postmating barrier in which pollen arrest occurs in only one direction of an interspecific cross. We investigated the genetic basis of pistil-side UI between Solanum species, with the specific goal of understanding the role and magnitude of epistasis between UI QTL. Using heterospecific introgression lines (ILs) between Solanum pennellii and S. lycopersicum, we assessed the individual and pairwise effects of three chromosomal regions (ui1.1, ui3.1, and ui12.1) previously associated with interspecific UI among Solanum species. Specifically, we generated double introgression (‘pyramided’) genotypes that combined ui12.1 with each of ui1.1 and ui3.1, and assessed the strength of UI pollen rejection in the pyramided lines, compared to single introgression genotypes. We found that none of the three QTL individually showed UI rejection phenotypes, but lines combining ui3.1 and ui12.1 showed significant pistil-side pollen rejection. Furthermore, double ILs (DILs) that combined different chromosomal regions overlapping ui3.1 differed significantly in their rate of UI, consistent with at least two genetic factors on chromosome three contributing quantitatively to interspecific pollen rejection. Together, our data indicate that loci on both chromosomes 3 and 12 are jointly required for the expression of UI between S. pennellii and S. lycopersicum, suggesting that coordinated molecular interactions among a relatively few loci underlie the expression of this postmating prezygotic barrier. In addition, in conjunction with previous data, at least one of these loci appears to also contribute to conspecific self-incompatibility (SI), consistent with a partially shared genetic basis between inter- and intraspecific mechanisms of postmating prezygotic female choice.

scholarly journals Transmission-Ratio Distortion Through F1 Females at Chromosome 11 Loci Linked to Om in the Mouse DDK Syndrome

Genetics ◽  
1996 ◽  
Vol 142 (4) ◽  
pp. 1299-1304
Author(s):  
F Pardo-Manuel de Villena ◽  
C Slamka ◽  
M Fonseca ◽  
A K Naumova ◽  
J Paquette ◽  
...  
Keyword(s):  
Genetic Model ◽  
Inbred Mouse ◽  
Transmission Ratio Distortion ◽  
Transmission Ratio ◽  
F1 Hybrids ◽  
Mouse Strains ◽  
Inbred Mouse Strains ◽  
Chromosome 11 ◽  
Ratio Distortion

Abstract We determined the genotypes of >200 offspring that are survivors of matings between female reciprocal F1 hybrids (between the DDK and C57BL/6J inbred mouse strains) and C57BL/6J males at markers linked to the Ovum mutant (Om) locus on chromosome 11. In contrast to the expectations of our previous genetic model to explain the “DDK syndrome,” the genotypes of these offspring do not reflect preferential survival of individuals that receive C57BL/6J alleles from the F1 females in the region of chromosome 11 to which the Om locus has been mapped. In fact, we observe significant transmission-ratio distortion in favor of DDK alleles in this region. These results are also in contrast to the expectations of Wakasugi's genetic model for the inheritance of Om, in which he proposed equal transmission of DDK and non-DDK alleles from F1 females. We propose that the results of these experiments may be explained by reduced expression of the maternal DDK Om allele or expression of the maternal DDK Om allele in only a portion of the ova of F1 females

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