scholarly journals A 2.09 Mb fragment translocation on chromosome 6 causes abnormalities during meiosis and leads to less seed watermelon

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Shujuan Tian ◽  
Jie Ge ◽  
Gongli Ai ◽  
Jiao Jiang ◽  
Qiyan Liu ◽  
...  
Keyword(s):  
Fragment Size ◽  
Citrullus Lanatus ◽  
Pollen Viability ◽  
Chromosome Translocation ◽  
Chromosome 6 ◽  
Spontaneous Mutant ◽  
Population Genetic Analysis ◽  
Chromosome Fragment ◽  
Hybrid Plants ◽  
Diploid Level

AbstractSeedlessness is a valuable agronomic trait in watermelon (Citrullus lanatus) breeding. Conventional less seed watermelons are mainly triploid, which has many disadvantages due to unbalanced genome content. Less seed watermelon can be achieved at the diploid level when certain reproductive genes are mutated or by chromosome translocation, which leads to defects during meiosis. However, the formation mechanism of diploid less seed watermelons remains largely unknown. Here, we identified a spontaneous mutant line, watermelon line “148”, which can set seeds normally when self-pollinated. A total of 148 × JM F1 hybrid plants exhibited seed number reductions to 50.3% and 47.3% of those of the two parental lines, respectively, which are considered to be less seed. Examination of pollen viability and hybridization experiments revealed that F1 hybrids produce semisterile pollen and ovules. Further cytological observations indicated that semisterility was a result of a reciprocal translocation of chromosomes, which exhibited one quadrivalent ring of four chromosomes at prometaphase I during meiosis. RT-qPCR analysis indirectly confirmed that the semisterile phenotype is caused by chromosome translocation rather than disruption of specific meiotic gene expression. F2 population genetic analysis indicated that the “148” watermelon line is a homozygous translocation and that the less seed phenotype of the F1 hybrid is prompted by one chromosome fragment translocation. The translocated fragment was further fine mapped to a 2.09 Mb region on chromosome 6 by whole-genome resequencing and genetic map cloning procedures. Our work revealed that a 2.09 Mb chromosome fragment translocation on chromosome 6, causing meiotic defects at metaphase I during meiosis, leads to diploid less seed watermelon. Our findings provide a new promising method for less seed watermelon breeding at the diploid level, as well as a fragment size reference for breeding less seed watermelon through artificially induced chromosome translocation.

Transmission of a wheat alien chromosome translocation with resistance to the wheat curl mite in common wheat, Triticum aestivum L.

1986 ◽  
Vol 28 (2) ◽  
pp. 294-297 ◽  
Author(s):  
E. D. P. Whelan ◽  
R. L. Conner ◽  
J. B. Thomas ◽  
A. D. Kuzyk
Keyword(s):  
Triticum Aestivum ◽  
Common Wheat ◽  
Triticum Aestivum L ◽  
Chromosome Translocation ◽  
Chromosome 6 ◽  
Selfed Progeny ◽  
Wheat Curl Mite ◽  
Aceria Tulipae ◽  
Group 6 ◽  
Homozygous Resistant

A translocation between a common wheat (Triticum aestivum L.) chromosome and chromosome 6 of Elytrigia pontica (Podp.) Holub conferred resistance to feeding by Eriophyes (= Aceria) tulipae Keifer, the mite vector of wheat streak mosaic virus and the wheat spot mosaic agent. Resistance was dominant, but differential transmission occurred between the pollen and the egg. Transmission of resistance through the pollen was low, about 3% in 'Cadet', 'Rescue', and 'Winalta', but significantly higher in 'Norstar' (9.1%). Significant differences also were detected in transmission through the egg. 'Cadet' had the highest transmission (50.9%) and 'Rescue' the lowest (40.5%). However, there were no significant differences among varieties in the frequencies of resistance (50.3–54.5%) in the F2. Less than 10% of the F2 plants were homozygous resistant. Selfed progeny from monosomic or disomic F1 plants from crosses between the homozygous translocation and group-6 monosomics all segregated for susceptibility. Meiotic studies of 25 susceptible F2 plants from these F1 monosomics showed that 21 were either monosomic or disomic and only 4 were nullisomic, indicating that the translocation did not involve any of the group-6 homoeologues. The translocation is considered to be a noncompensating translocation involving a whole arm of chromosome 6 of E. pontica.Key words: wheat, mite (wheat curl), translocation, Triticum.

scholarly journals Pollen Viability of Selected Diploid Watermelon Pollenizer Cultivars

HortScience ◽  
2008 ◽  
Vol 43 (1) ◽  
pp. 274-275 ◽  
Author(s):  
Josh H. Freeman ◽  
Stephen M. Olson ◽  
Eileen A. Kabelka
Keyword(s):  
Fruit Quality ◽  
Fruit Set ◽  
Citrullus Lanatus ◽  
Pollen Viability ◽  
Viable Pollen ◽  
Diploid Cultivar ◽  
Triploid Watermelon

In the Spring and Fall 2006, the pollen viability of four diploid watermelon pollenizers was evaluated in Quincy, FL. Triploid watermelon plants [Citrullus lanatus (Thunb.) Matsum. & Nakai.] do not produce sufficient viable pollen to pollenize themselves and a diploid cultivar must be interplanted as a pollen source. Recent studies have illustrated differences in triploid watermelon yields as a result of the pollenizer cultivar used. The viability of the pollen produced by pollenizer cultivars may greatly influence the fruit set and fruit quality in the triploid watermelon crop. Pollen samples were taken from ‘Companion’, ‘Jenny’, ‘Mickylee’, and ‘SP-1’ and were stained to determine their viability. There were no significant differences in pollen viability among cultivars and all cultivars had high average viability. Pollen viability was never lower than 95% for any cultivar. This study indicates that pollen viability of the cultivars evaluated should not influence their effectiveness as pollenizers.

scholarly journals Hazelnut Pollen Phenotyping Using Label-Free Impedance Flow Cytometry

2020 ◽  
Vol 11 ◽  
Author(s):  
Lorenzo Ascari ◽  
Valerio Cristofori ◽  
Federico Macrì ◽  
Roberto Botta ◽  
Cristian Silvestri ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Pollen Viability ◽  
Central Italy ◽  
Chromosome Translocation ◽  
Pollen Sterility ◽  
Tree Canopy ◽  
Label Free ◽  
Lab On Chip ◽  
Pollen Hydration ◽  
Chip Technology

Impedance flow cytometry (IFC) is a versatile lab-on-chip technology which enables fast and label-free analysis of pollen grains in various plant species, promising new research possibilities in agriculture and plant breeding. Hazelnut is a monoecious, anemophilous species, exhibiting sporophytic self-incompatibility. Its pollen is dispersed by wind in midwinter when temperatures are still low and relative humidity is usually high. Previous research found that hazelnut can be characterized by high degrees of pollen sterility following a reciprocal chromosome translocation occurring in some cultivated genotypes. In this study, IFC was used for the first time to characterize hazelnut pollen biology. IFC was validated via dye exclusion in microscopy and employed to (i) follow pollen hydration over time to define the best pre-hydration treatment for pollen viability evaluation; (ii) test hazelnut pollen viability and sterility on 33 cultivars grown in a collection field located in central Italy, and two wild hazelnuts. The accessions were also characterized by their amount and distribution of catkins in the tree canopy. Pollen sterility rate greatly varied among hazelnut accessions, with one main group of highly sterile cultivars and a second group, comprising wild genotypes and the remaining cultivars, producing good quality pollen. The results support the hypothesis of recurring reciprocal translocation events in Corylus avellana cultivars, leading to the observed gametic semi-sterility. The measured hazelnut pollen viability was also strongly influenced by pollen hydration (Radj2 = 0.83, P ≤ 0.0001) and reached its maximum at around 6 h of pre-hydration in humid chambers. Viable and dead pollen were best discriminated at around the same time of pollen pre-hydration, suggesting that high humidity levels are required for hazelnut pollen to maintain its functionality. Altogether, our results detail the value of impedance flow cytometry for high throughput phenotyping of hazelnut pollen. Further research is required to clarify the causes of pollen sterility in hazelnut, to confirm the role of reciprocal chromosome translocations and to investigate its effects on plant productivity.

The (6;9) chromosome translocation, associated with a specific subtype of acute nonlymphocytic leukemia, leads to aberrant transcription of a target gene on 9q34

1990 ◽  
Vol 10 (8) ◽  
pp. 4016-4026
Author(s):  
M von Lindern ◽  
A Poustka ◽  
H Lerach ◽  
G Grosveld
Keyword(s):  
Long Range ◽  
Cdna Cloning ◽  
Target Gene ◽  
Chromosomal Translocation ◽  
Chromosome Translocation ◽  
Chromosome 9 ◽  
Chromosome 6 ◽  
Acute Nonlymphocytic Leukemia ◽  
Chromosome Walking ◽  
Chromosome Isolation

The specific (6;9)(p23;q34) chromosomal translocation is associated with a defined subtype of acute nonlymphocytic leukemia (ANLL). The 9q34 breakpoint is located at the telomeric side of the c-abl gene. Through a combination of chromosome jumping, long-range mapping, and chromosome walking, the chromosome 9 breakpoints of several t(6;9) ANLL patients were localized within a defined region of 8 kilobases (kb), 360 kb telomeric of c-abl. Subsequent cDNA cloning revealed that this region represented an intron in the middle of a gene, called Cain (can), encoding a 7.5-kb transcript. Disruption of the can gene by the translocation resulted in the expression of a new 5.5-kb can mRNA from the 6p- chromosome. Isolation of chromosome 6 sequences showed that breakpoints on 6p23 also clustered within a limited stretch of DNA. These data strongly suggest a direct involvement of the translocation in the leukemic process of t(6;9) ANLL.

scholarly journals Pollen Viability of F1 Hybrids between Watermelon Cultivars and Disease-resistant, Infraspecific Crop Wild Relatives

HortScience ◽  
2013 ◽  
Vol 48 (12) ◽  
pp. 1428-1432 ◽  
Author(s):  
Cecilia E. McGregor ◽  
Vickie Waters
Keyword(s):  
Citrullus Lanatus ◽  
Pollen Viability ◽  
Chromosomal Rearrangements ◽  
Crop Wild Relatives ◽  
Wild Relatives ◽  
Low Fertility ◽  
F1 Hybrids ◽  
Linkage Drag ◽  
Sources Of Variation ◽  
The Cross

Crop wild relatives (CWRs) are important sources of variation for domesticated crops like watermelon (Citrullus lanatus) where cultivated varieties have a very narrow genetic base. The use of CWRs in plant breeding can be hampered by low fertility, chromosomal rearrangements, marker distortion, and linkage drag in the progeny. Pollen viability can be a quick and easy way to estimate male fertility, which can be a cause of marker distortion and an indicator of chromosomal rearrangements. Pollen viability was determined for F1 hybrids between cultivars and resistant citron and egusi types and the data were used to determine whether the parental cultivars/lines used or the directionality of the cross play a role in pollen viability. F1 hybrids between cultivars and the egusi type showed no reduction in pollen viability compared with parental lines, whereas pollen viability of hybrids with citron types varied between 61.8% and 91.7%. Significant main effects were observed for the cultivar and donor lines used, but the directionality of the cross did not affect pollen viability. F1 hybrids with ‘Crimson Sweet’ as the cultivar parent had significantly higher pollen viability than those with ‘Sugar Baby’ or ‘Charleston Gray’. Our results indicate that the directionality of the crosses between watermelon cultivars and infraspecific CWRs does not affect pollen viability but that the specific cultivars and donor lines used can have a significant effect. The high pollen viability of cultivar–egusi hybrids is supported by previous genetic data and strongly suggests that it should be easier to introgress traits from egusi types than citron types.

Interspecific Crossability of Nine Diploid Fragaria Species

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 483b-483 ◽  
Author(s):  
Bob Bors ◽  
J. Alan Sullivan
Keyword(s):  
Seed Set ◽  
Fragaria Vesca ◽  
Good Seed ◽  
Cotyledon Stage ◽  
Hybrid Plants ◽  
Group A ◽  
Group B ◽  
Diploid Level ◽  
Interspecific Crossability ◽  
Genomic Similarity

As part of a wild species introgression program, Fragaria vesca, F. viridis, F. nubicola, F. nipponica, F. nilgerrensis, F. pentaphylla, F. gracilis, F. daltoniana, and F. iinumae were crossed in most combinations possible, the exceptions being F. daltoniana and F. iinumae, which produced only a few flowers each. Crosses with F. vesca as a female and either F. gracilis, F. nipponica, or F. iinumae as males produced good seed set, but seedlings died in the cotyledon stage in every case. No seed set occurred when F. iinumae was crossed with F. viridis or F. nubicola. F. pentaphylla, F. gracilis, and F. iinumae were observed to be self-incompatible while F. daltoniana was self-compatible. Three overlapping groups based on crossing data have emerged. Within the following groups, hybrid plants were obtained in all species combinations, although not necessarily for reciprocal combinations: Group A: F. vesca, F. viridis, F. nubicola, and F. pentaphylla. Group B: F. vesca, F. nilgerrensis, F. daltoniana, and F. pentaphylla. Group C: F. pentaphylla, F. gracilis, and F. nipponica. Fertile or semifertile diploid hybrids were obtained for all species combinations within group A indicating genomic similarity or that breeding at the diploid level could occur with these species. Fertility has not been determined for hybrids in groups B and C. It is interesting to note the presence of F. pentaphylla in all three groups, perhaps this species plays an important role in Fragaria evolution.

Genetic compatibility among domesticated and wild accessions of the tropical tuberous legume Vigna vexillata (L.) A. Rich.

2010 ◽  
Vol 61 (10) ◽  
pp. 785 ◽  
Author(s):  
F. Damayanti ◽  
R. J. Lawn ◽  
L. M. Bielig
Keyword(s):  
Pollen Viability ◽  
Pollen Grains ◽  
The Other ◽  
Genetic Compatibility ◽  
Vigna Vexillata ◽  
Hybrid Plants ◽  
Hand Pollination ◽  
Viable Seeds ◽  
Wild Accessions ◽  
Fertile Hybrids

Phenotypic similarities and differences between a cultivated variety of the tuberous legume Vigna vexillata from Bali, Indonesia, the putative domesticated variety macrosperma and wild types from Africa, Australia and Indonesia, were reported previously. The present study was undertaken to establish the genetic compatibility of these three accession classes. Seventeen accessions, comprising eight cultivated Bali accessions, one var. macrosperma accession and eight wild accessions from Africa and Austronesia, were grown in large pots in shade house facilities in Townsville, Australia. Not all hybrid combinations were attempted because for some accession combinations, suitable matching flowers were not available at the same time. The main aim was to attempt enough crosses between accessions from the respective classes to establish whether the classes were genetically compatible. Hybridisation was conducted by hand pollination in the morning, using newly-open flowers that had been emasculated before sunset on the day before. Pods and viable hybrid seed were obtained from the Bali × Bali, var. macrosperma × wild and wild African × wild Austronesian combinations. However, difficulty was encountered in obtaining viable and/or self-fertile hybrids between the Bali accessions and the other two classes. Depending on the particular combination of parental accessions, different genetic breakdown mechanisms were observed with the Bali × var. macrosperma and Bali × wild combinations. In some instances, flowers failed to set pods and/or the young pods abscised before maturity; pods set but seed were shrivelled and/or non-viable; viable seeds were set but the hybrid seedling plants were short-lived; or, in a few instances (Jimbaran Bali × wild Austronesian), vigorous hybrid plants were obtained but were self-sterile. Mitotic chromosome counts showed there was no difference in chromosome number between the Bali accessions, the Austronesian accessions and those hybrids that were viable but infertile. All exhibited 2n = 22. Pollen viability analyses using Alexander’s stain indicated that the numbers of pollen grains per flower and the percentages of pollen grain that were viable were substantially lower in the hybrids than in both the cultivated Bali and wild parental accessions. Consistent with this observation, small numbers of viable seeds were obtained when viable pollen from the respective parents was backcrossed onto the self-sterile hybrids. The results suggested that the cultivated Bali accessions do not belong to the same primary gene pool as the other cultivated and wild V. vexillata accessions and that it would be difficult to use the Bali accessions and var. macrosperma concurrently to breed seed crop varieties. A taxonomic review of V. vexillata is also warranted.

Analysis of pollen fertility in aneuploid hybrids with substitutions for specific chromosomes or their arms in cotton G.hirsutum L.

Biomics ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 376-379
Author(s):  
M.F. Sanamyan ◽  
Sh.U. Bobokhujaev
Keyword(s):  
Pollen Fertility ◽  
Chromosome 7 ◽  
F1 Hybrids ◽  
Chromosome 6 ◽  
Chromosome 2 ◽  
Chromosome 4 ◽  
Strong Decrease ◽  
Cotton Genome ◽  
Hybrid Plants

Analysis of pollen fertility in interspecific aneuploid F1 hybrids with substitutions of specific chromosomes (2, 4, 6, 7, 18) and chromosome arms (telo 6, telo11) of the cotton genome G. hirsutum L. revealed a decrease in fertility in all hybrid plants. It was shown that hybrid monosomics for chromosome 2 were characterized by a slight decrease in pollen fertility; hybrid monosomics of different families with substitution on chromosome 4 and on chromosome 6 - a significant decrease; hybrid monosomics with substitution on chromosome 7 and 18, as well as monotelodisome hybrid plants with substitution of an individual arm of chromosome 6 or 11 - a strong decrease, which indicated the existence of specific differences in pollen fertility in hybrid monosomic plants with substitution of specific chromosomes of the cotton genome due to the formation of partially unbalanced haplo-deficient gametes.

scholarly journals Cytological Evidence for the Sterility of an Interspecific Alstroemeria Hybrid

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 855B-855
Author(s):  
Chunsheng Lu ◽  
Mark Bridgen
Keyword(s):  
Pollen Mother Cell ◽  
Late Stage ◽  
Interspecific Hybrid ◽  
Mother Cell ◽  
Seed Set ◽  
Pollen Viability ◽  
Pollen Grains ◽  
Cytological Evidence ◽  
Stage Of Development ◽  
Hybrid Plants

Self-pollinations of a diploid (2n = 2x = 16) interspecific hybrid from the cross of Alstroemeria aurea × A. caryophyllaea resulted in no seed set. Pollen viability studies with the hybrid demonstrated that only 5% of the pollen grains were viable. Cytological observations with the hybrid pollen mother cell (PMC) revealed abnormal chromosome behaviors, such as no pairing in Prophase I and Metaphase I, and bridges in the Anaphase I and II. Although the development of microspores appeared normal in shape until the stage of tetrad release, some chromosomes did not remain in the nucleus after completing meiosis, formed isolated groups of 1 to 4, and remained in the cytoplasm. This genetic imbalance of the microspores could be one of the causes for the abortion of the pollen grains in the late stage of development. Additional meiotic cytological studies with colchicine-induced tetraploids (2n = 4x = 32) derived from the hybrid plants showed that chromosome pairings were normal in most cases. However, self-pollination with the tetraploid plants failed to set seeds. These studies with the tetraploids further demonstrate that the sterility of the hybrid is due not only to chromosomal differences, but also to complex genic interactions.

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