scholarly journals Rare instances of haploid inducer DNA in potato dihaploids and ploidy-dependent genome instability

2020 ◽  
Author(s):  
Kirk R Amundson ◽  
Benny Ordoñez ◽  
Monica Santayana ◽  
Mwaura Livingstone Nganga ◽  
Isabelle M Henry ◽  
...  
Keyword(s):  
Genome Instability ◽  
Paternal Chromosome ◽  
Haploid Induction ◽  
Paternal Genome ◽  
Tetraploid Potato ◽  
Introgression Breeding ◽  
Chromosome Breaks ◽  
Haploid Inducer ◽  
Chromosomal Breaks ◽  
Tetraploid Progeny

AbstractIn cultivated tetraploid potato, reduction to diploidy (dihaploidy) allows hybridization to diploid germplasm, introgression breeding, and may facilitate the production of inbreds. Pollination with haploid inducers yields maternal dihaploids, as well as triploid and tetraploid hybrids. It is not known if dihaploids result from parthenogenesis, entailing development of embryos from unfertilized eggs, or genome elimination, entailing missegregation and loss of paternal chromosomes. A sign of genome elimination is the occasional persistence of haploid inducer DNA in some of the dihaploids. We characterized the genomes of 1,001 putative dihaploids and 134 hybrids produced by pollinating tetraploid clones with three haploid inducers, IVP35, IVP101, and PL4. We detected inheritance of full or partial chromosomes from the haploid inducer parent in 0.87% of the overall dihaploid progeny, irrespective of the combination of parental genotypes. Chromosomal breaks commonly affected the paternal genome in the dihaploid and tetraploid progeny, but not in the triploid progeny. Residual haploid inducer DNA is consistent with genome elimination as the mechanism of haploid induction. Further, the fact that paternal chromosome breaks are specific to dihaploids and tetraploid progeny suggests that they may be specific to 2x sperms, and supports the hypothesis that 2x sperms facilitate genome elimination.

Doubled haploid production in maize under Sub-montane Himalayan conditions using R1-nj-based haploid inducer TAILP1

2020 ◽  
Vol 80 (03) ◽  
Author(s):  
R. K Khulbe ◽  
A. Pattanayak ◽  
Lakshmi Kant ◽  
G. S. Bisht ◽  
M. C. Pant ◽  
...  
Keyword(s):  
Doubled Haploid ◽  
Sweet Corn ◽  
Haploid Induction ◽  
Maize Breeding ◽  
Line Production ◽  
Haploid Inducer ◽  
Breeding Programmes ◽  
Source Populations ◽  
Developmental Phases

The use of in vivo haploid induction system makes the doubled haploid (DH) technology easier to adopt for the conventional maize breeders. However, despite having played an important role in the initial developmental phases of DH technology, Indian maize research has yet to harvest its benefits. Haploid Inducer Lines (HILs) developed by CIMMYT are being widely used in maize breeding programmes in many countries including India. There, however, is no published information on the efficiency of DH line production using CIMMYT HILs in Indian maize breeding programmes. In the present study, the efficiency of DH production using CIMMYT’s tropically adapted inducer line TAILP1 was investigated with eight source populations including two of sweet corn. The average haploid induction rate (HIR) of TAILP1 was 5.48% with a range of 2.01 to 10.03%. Efficiency of DH production ranged from 0.14 to 1.87% for different source populations with an average of 1.07%. The information generated will be useful for maize breeders intending to use DH technology for accelerated development of completely homozygous lines.

Haploid Induction and Genome Instability

2019 ◽  
Vol 35 (11) ◽  
pp. 791-803 ◽  
Author(s):  
Luca Comai ◽  
Ek Han Tan
Keyword(s):  
Genome Instability ◽  
Haploid Induction

scholarly journals Molecular marker analysis of 24- and 25-chromosome plants obtained from Solanum tuberosum L. subsp. andigena (2n = 4x = 48) pollinated with a Solanum phureja haploid inducer

Genome ◽  
2002 ◽  
Vol 45 (3) ◽  
pp. 577-583 ◽  
Author(s):  
Y Samitsu ◽  
K Hosaka
Keyword(s):  
Solanum Tuberosum ◽  
Solanum Tuberosum L ◽  
Single Copy ◽  
Solanum Phureja ◽  
Rflp Markers ◽  
Haploid Induction ◽  
Haploid Inducer ◽  
Rflp Rapd ◽  
Molecular Marker Analysis ◽  
Almost All

Clones with 24 or 25 chromosomes were obtained by pollinating an Andean cultivated tetraploid potato (Solanum tuberosum subsp. andigena clone 94H94, 2n = 4x = 48) with the Solanum phureja haploid-inducer clone 1.22. Their genetic composition was analyzed in an RAPD assay using 135 decamer primers and in an RFLP assay using 45 single-copy DNA probes. In total, 22 RAPD and 20 RFLP markers were found to be specific to S. phureja. None of these markers were found in the 24- and 25-chromosome clones. RFLP genotypes for the 45 RFLP loci were further determined for each clone. Genotypes of the 24-chromosome clones were characterized using two alleles randomly selected from four alleles of the parental tetraploid clone for almost all RFLP loci. Five 25-chromosome clones had extra alleles for all of the RFLP loci of chromosomes 4, 8, 10, 11, and 12, respectively, suggesting primary trisomy for one of these chromosomes. Clones with genotypes showing double reduction were also identified. Therefore, the obtained clones likely originated from random samples of female gametes, and hence are euhaploids or aneuhaploids of S. tuberosum subsp. andigena, strongly supporting parthenogenesis to be a primary mechanism for haploid induction in potato.Key words: Solanum tuberosum subsp. andigena, RFLP, RAPD, haploid, trisomic.

scholarly journals PLOIDY BARRIER TO ENDOSPERM DEVELOPMENT IN MAIZE

Genetics ◽  
1984 ◽  
Vol 107 (1) ◽  
pp. 103-115
Author(s):  
Bor-Yaw Lin
Keyword(s):  
Ploidy Level ◽  
Present Finding ◽  
Endosperm Development ◽  
Viable Seed ◽  
Paternal Chromosome ◽  
Maize Endosperm ◽  
Female Side ◽  
Diploid Males ◽  
Paternal Genome ◽  
Maize Kernels

ABSTRACT Maize kernels inheriting the indeterminate gametophyte mutant (ig) on the female side had endosperms that ranged in ploidy level from diploid (2x) to nonaploid (9x). In crosses with diploid males, only kernels of the triploid endosperm class developed normally. Kernels of the tetraploid endosperm class were half-sized but with well-developed embryos that regularly germinated. Kernels of endosperm composition other than triploid or tetraploid were abortive.—Endosperm ploidy level resulting from mating ig/igx tetraploid Ig similarly was variable. Most endosperms started to degenerate soon after pollination and remained in an arrested state. Hexaploid endosperm was exceptional; it developed normally during the sequence of stages studied and accounted for plump kernels on mature ears. Since such kernels have diploid maternal tissues (pericarp) but triploid embryos, the present finding favors the view that endosperm failure or success in such circumstances is governed by conditions within the endosperm itself.—Whereas tetraploid endosperm consisting of three maternal genomes and one paternal genome is slightly reduced in size but supports viable seed development, that endosperm having two maternal and two paternal chromosome sets was highly defective and conditioned abortion. Thus, development of maize endosperm evidently is affected by the parental source of its sets of chromosomes.

scholarly journals Development of In Vivo Haploid Inducer Lines for Screening Haploid Immature Embryos in Maize

Plants ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 739
Author(s):  
Chen Chen ◽  
Zijian Xiao ◽  
Junwen Zhang ◽  
Wei Li ◽  
Jinlong Li ◽  
...  
Keyword(s):  
Doubled Haploid ◽  
Immature Embryos ◽  
Haploid Induction ◽  
Haploid Induction Rate ◽  
Induction Rate ◽  
Haploid Inducer ◽  
Breeding Populations ◽  
Selection For ◽  
Doubled Haploid Breeding

Doubled haploid technology is widely applied in maize. The haploid inducer lines play critical roles in doubled haploid breeding. We report the development of specialized haploid inducer lines that enhance the purple pigmentation of crossing immature embryos. During the development of haploid inducer lines, two breeding populations derived from the CAU3/S23 and CAU5/S23 were used. Molecular marker-assisted selection for both qhir1 and qhir8 was used from BC1F1 to BC1F4. Evaluation of the candidate individuals in each generation was carried out by pollinating to the tester of ZD958. Individuals with fast and clear pigmentation of the crossing immature embryos, high number of haploids per ear, and high haploid induction rate were considered as candidates. Finally, three new haploid inducer lines (CS1, CS2, and CS3) were developed. The first two (CS1 and CS2) were from the CAU3/S23, with a haploid induction rate of 8.29%–13.25% and 11.54%–15.54%, respectively. Meanwhile, the CS3 was from the CAU5/S23. Its haploid induction rate was 8.14%–12.28%. In comparison with the donor haploid inducer lines, the 24-h purple embryo rates of the newly developed haploid inducer lines were improved by 10%–20%, with a ~90% accuracy for the identification of haploid immature embryos. These new haploid inducer lines will further improve the efficiency of doubled haploid breeding of maize.

The paternal sex ratio chromosome in the parasitic wasp Trichogramma kaykai condenses the paternal chromosomes into a dense chromatin mass

Genome ◽  
2003 ◽  
Vol 46 (4) ◽  
pp. 580-587 ◽  
Author(s):  
Joke F.A van Vugt ◽  
Merijn Salverda ◽  
J Hans de Jong ◽  
Richard Stouthamer
Keyword(s):  
Sex Ratio ◽  
Parasitic Wasp ◽  
Parasitoid Wasp ◽  
B Chromosome ◽  
The Other ◽  
Paternal Chromosome ◽  
Paternal Genome ◽  
Obvious Similarity ◽  
Dense Chromatin ◽  
Paternal Sex Ratio

A recently discovered B chromosome in the parasitoid wasp Trichogramma kaykai was found to be transmitted through males only. Shortly after fertilization, this chromosome eliminates the paternal chromosome set leaving the maternal chromosomes and itself intact. Consequently, the sex ratio in these wasps is changed in favour of males by modifying fertilized diploid eggs into male haploid offspring. In this study, we show that in fertilized eggs at the first mitosis the paternal sex ratio (PSR) chromosome condenses the paternal chromosomes into a so-called paternal chromatin mass (PCM). During this process, the PSR chromosome is morphologically unaffected and is incorporated into the nucleus containing the maternal chromosomes. In the first five mitotic divisions, 67% of the PCMs are associated with one of the nuclei in the embryo. Furthermore, in embryos with an unassociated PCM, all nuclei are at the same mitotic stage, whereas 68% of the PCM-associated nuclei are at a different mitotic phase than the other nuclei in the embryo. Our observations reveal an obvious similarity of the mode of action of the PSR chromosome in T. kaykai with that of the PSR-induced paternal genome loss in the unrelated wasp Nasonia vitripennis.Key words: paternal sex ratio, PSR, Trichogramma kaykai, B chromosome, paternal chromatin mass, embryogenesis.

scholarly journals Parental origin effects in mice

Development ◽  
1986 ◽  
Vol 97 (Supplement) ◽  
pp. 137-150
Author(s):  
B. M. Cattanach
Keyword(s):  
Embryonic Development ◽  
Normal Development ◽  
Full Term ◽  
Nuclear Transplantation ◽  
Parental Origin ◽  
Paternal Chromosome ◽  
Paternal Genome ◽  
Maternal Genome ◽  
Transplantation Experiments ◽  
Hydatidiform Moles

Nuclear transplantation experiments in mice, reviewed elsewhere in this Symposium, have clearly demonstrated that the maternal and paternal genomes from which the embryo is formed are not functionally equivalent. The paternal genome appears to be essential for the normal development of extraembryonic tissues and the maternal genome for some stage of embryonic development. These findings provide some explanation for the observations that in mammals diploid parthenotes possessing two maternal genomes fail to survive (Markert, 1982) and that, in man, embryos with two paternal chromosome sets are inviable, forming hydatidiform moles (Kajii & Ohama, 1977). It has been proposed that a specific ‘imprinting’ of the paternal genomes occurs during gametogenesis so that the presence of both a female and male pronculeus is essential in an egg for full-term development (Barton, Surani & Norris, 1984; McGrath & Solter, 1984a; Surani, Barton & Norris, 1984).

scholarly journals Mechanistic basis for microhomology identification and genome scarring by polymerase theta

2020 ◽  
Vol 117 (15) ◽  
pp. 8476-8485 ◽  
Author(s):  
Juan Carvajal-Garcia ◽  
Jang-Eun Cho ◽  
Pablo Carvajal-Garcia ◽  
Wanjuan Feng ◽  
Richard D. Wood ◽  
...  
Keyword(s):  
Dna Polymerase ◽  
De Novo ◽  
Genome Instability ◽  
End Joining ◽  
Complementary Sequence ◽  
Chromosome Breaks ◽  
Complete Repair ◽  
Cancer Genomes ◽  
Mechanistic Basis ◽  
Scanning Mechanism

DNA polymerase theta mediates an end joining pathway (TMEJ) that repairs chromosome breaks. It requires resection of broken ends to generate long, 3′ single-stranded DNA tails, annealing of complementary sequence segments (microhomologies) in these tails, followed by microhomology-primed synthesis sufficient to resolve broken ends. The means by which microhomologies are identified is thus a critical step in this pathway, but is not understood. Here we show microhomologies are identified by a scanning mechanism initiated from the 3′ terminus and favoring bidirectional progression into flanking DNA, typically to a maximum of 15 nucleotides into each flank. Polymerase theta is frequently insufficiently processive to complete repair of breaks in microhomology-poor, AT-rich regions. Aborted synthesis leads to one or more additional rounds of microhomology search, annealing, and synthesis; this promotes complete repair in part because earlier rounds of synthesis generate microhomologies de novo that are sufficiently long that synthesis is more processive. Aborted rounds of synthesis are evident in characteristic genomic scars as insertions of 3 to 30 bp of sequence that is identical to flanking DNA (“templated” insertions). Templated insertions are present at higher levels in breast cancer genomes from patients with germline BRCA1/2 mutations, consistent with an addiction to TMEJ in these cancers. Our work thus describes the mechanism for microhomology identification and shows how it both mitigates limitations implicit in the microhomology requirement and generates distinctive genomic scars associated with pathogenic genome instability.

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