Genetic and cytogenetic analyses of the A genome of Triticum monococcum. III. Cytology, breeding behavior, fertility, and morphology of autotriploids

1986 ◽  
Vol 28 (5) ◽  
pp. 867-887 ◽  
Author(s):  
J. Kuspira ◽  
R. N. Bhambhani ◽  
R. S. Sadasivaiah ◽  
D. Hayden
Keyword(s):  
Diploid Species ◽  
Leaf Size ◽  
Kernel Weight ◽  
Triticum Monococcum ◽  
High Fertility ◽  
Breeding Behavior ◽  
Seed Fertility ◽  
A Genome ◽  
Cytogenetic Analyses

Mature triploid seed from reciprocal (2n = 4x × 2n = 2x) crosses in Triticum monococcum was minute and shrivelled because of endosperm collapse and therefore failed to germinate. This necessitated the excision of embryos from successful pollinations and their growth in vitro to ensure subsequent germination so as to obtain viable and vigorous autotriploids. A comparison of these triploids with their diploid and tetraploid progenitors revealed that cell size, kernel weight, and pistil size increased with an increase in ploidy level. However, unlike other species, optimum expression was observed in these triploids for plant height, tillering, size of spikes, number of spikelets/spike, and leaf size. Earliness, althoughenhanced in tetraploids relative to diploids, was delayed in the triploids. Mean numbers of univalents, bivalents, and trivalents per microsporocyte were 2.65, 2.60, and 4.38, respectively. Only chains (93.5%), which formed V-shaped metaphase I (MI) configurations, frying pan (5.0%), and Y-shaped (1.5%) trivalent associations occurred. On the average, two reciprocal exchanges occurred per bivalent and trivalent. Trivalents corriented randomly at MI. At anaphase I, all sets of three homologues segreated randomly to the two poles, lagging univalents always divided equationally, and only meiocytes with such chromosomes formed micronuclei. The reasons for similarities and differences in meiotic behaviour of T. monococcum triploids with those of other species are discussed. Confirmation of the conclusions drawn with respect to the cytology of the triploids was obtained from similar cytological observations with primary single trisomics. These triploids produced euploids, primary single trisomics as well as some double and triple trisomics all of which differed phenotypically from diploids. Triticum monococcum, like most diploid species, is highly intolerant of aneuploidy. Possible reasons for the differences in levels of tolerance of aneuploidy in species like T. monococcum and those like Petunia hybrida, which are highly tolerant of aneuploidy, are discussed. Pollen fertility was high and seed fertility was very low. Reasons for the latter as well as the high fertility in species that are highly tolerant of aneuploidy and allotriploids are discussed.Key words: Triticum monococcum, autotriploid, trisomic, cytology, breeding behavior, fertility, morphology.

Genetic and cytogenetic analyses of the A genome of Triticum monococcum. I. Cytology, breeding behaviour, fertility, and morphology of induced autotetraploids

1985 ◽  
Vol 27 (1) ◽  
pp. 51-63 ◽  
Author(s):  
J. Kuspira ◽  
R. N. Bhambmani ◽  
T. Shimada
Keyword(s):  
Decisive Role ◽  
Leaf Size ◽  
Kernel Weight ◽  
Triticum Monococcum ◽  
Fertility Level ◽  
Breeding Behavior ◽  
Diploid Progenitor ◽  
Artificial Medium ◽  
A Genome ◽  
Cytogenetic Analyses

Autotetraploids were colchicine-induced in Triticum monococcum and, upon comparison to their diploid progenitor, possessed the following characteristics: (i) their cells were on the average 20.8% larger; (ii) plant height was reduced by 15% and tillering by 37.5%; (iii) spikes, 1000-kernel weight, pistil size (length (L)/weight (W), and leaf size (L/W) were 53.9, 51.2, 80/57.1, and 60/26.4% larger, respectively; and (iv) they were 12.4% earlier in heading. Observed mean numbers of univalents, bivalents, trivalents (linear, convergent, and indifferent coorientations), and quadrivalents (convergent and parallel alignments only) per microsporocyte at metaphase I were 0.62, 9.86, 0.23, and 1.74, respectively; 65.4% of all meiocytes possessed bivalents and (or) quadrivalents and produced balanced meiotic products; 34.6% also possessed univalents and (or) trivalents and, therefore, produced balanced and unbalanced meiotic products. The actual 70.9% balanced meiotic products falls within the calculated range of 65.4–81.3%. Our tetraploids breed true. Evidence and reasons for this are discussed. The fertility of our tetraploids was high (79.8%). Irregular chromosome behaviour during meiosis may play a decisive role in determining the fertility level. Genic factors may also be involved. Methods of improving fertility and whether chromosomal factors alone are responsible for tetraploid fertility levels are discussed. Mature seed from reciprocal 2n = 4x × 2n = 2x crosses was shrivelled because of endosperm collapse and did not germinate. Thus, embryo excision and culturing on artificial medium was required to obtain viable autotriploids.Key words: Triticum monococcum, autotetraploid, cytology, breeding behavior, fertility, morphology.

Genetic and cytogenetic analyses of the A genome of Triticum monococcum. IV. Synaptonemal complex formation in autotetraploids

Genome ◽  
1987 ◽  
Vol 29 (2) ◽  
pp. 309-318 ◽  
Author(s):  
C. B. Gillies ◽  
J. Kuspira ◽  
R. N. Bhambhani
Keyword(s):  
Synaptonemal Complex ◽  
Theoretical Models ◽  
Triticum Monococcum ◽  
Pachytene Nucleus ◽  
Lateral Element ◽  
A Genome ◽  
Cytogenetic Analyses ◽  
The Difference ◽  
Quadrivalent Frequency ◽  
Metaphase I

Electron microscopy of synaptonemal complex spreads from autotetraploid Triticum monococcum (2n = 4x = 28) revealed a minimum mean of 3.59 multivalents per zygotene–pachytene nucleus. The range of values was from 1 to 6 multivalents per nucleus. Most of the multivalents were quadrivalents with single, medially located pairing partner switch points. Lateral element pairing switches, particularly the few multiple switches, were often accompanied by extensive asynapsis around the switch point. The synaptonemal complex multivalent frequency is considerably higher than the metaphase I quadrivalent frequency previously reported for the same material. Calculations of expected pachytene quadrivalent frequency from metaphase I data, using several published theoretical models, gave values that did not agree with the results obtained here. The difference between the multivalent frequencies at pachytene and metaphase I does not appear to be the result of a correction process. Instead, it could be caused by a combination of preferential pairing or crossing-over and the effects of the position of partner switches and asynapsis associated with switches. Key words: autotetraploid, multivalents, synaptonemal complex, pairing effects.

Genetic and cytogenetic analyses of the A genome of Triticum monococcum. II. The mode of inheritance of spring versus winter growth habit

1986 ◽  
Vol 28 (1) ◽  
pp. 88-95 ◽  
Author(s):  
J. Kuspira ◽  
J. Maclagan ◽  
K. Kerby ◽  
R. N. Bhambhani
Keyword(s):  
Triticum Aestivum ◽  
Growth Habit ◽  
Major Gene ◽  
Diploid Species ◽  
Triticum Monococcum ◽  
Allelic Series ◽  
A Genome ◽  
Multiple Allelic Series ◽  
Winter Growth Habit ◽  
Mode Of Inheritance

The study on the mode of inheritance of spring versus winter growth habit in Triticum monococcum is the first in a diploid wheat species. The results are discussed in light of the information available on the genetics and cytogenetics of this character in Triticum aestivum. Two spring habit and six winter habit lines were used in these investigations. Statistical analyses of progenies in each of these lines clearly established the true-breeding nature of all eight lines with respect to days to heading. Analysis of F1 and F2 results of crosses between the two spring habit lines 68 and 293 showed the following: (i) neither line carries winter habit alleles at any of the major gene loci determining growth habit; and (ii) four of five minor allele pairs determine the phenotypic differences between them. Monohybrid F2 and testcross ratios in crosses between spring habit line 68 and each of the six winter lines lead to the following conclusions: (i) differences between spring and winter growth habit in each cross are due to alleles of one major gene; (ii) the allele for spring habit is completely dominant to that for winter habit in each cross; and (iii) all these lines are genotypically identical or very similar at all modifying gene loci. These results imply that only one major gene determines growth habit in this species. Diallel (critical) crosses among the six recessive lines indicate that complementation does not occur in any of the F1's. Therefore, all these recessive genes represent mutations in the same gene. If these results are characteristic of all winter lines in Triticum monococcum, they permit the initial conclusion that only one major gene determines growth habit in this diploid species. This locus is in all likelihood the VrnI locus since it is the only one of the five major genes identified for growth habit, that is present in the A genome of Triticum aestivum. All six recessive lines respond to natural vernalization. This lends further support to our initial conclusion. Because the six recessive lines head at five different times we conclude that a multiple allelic series occurs at this locus. Specifically, at least three and probably five recessive alleles responsible for different heading dates among the winter lines, and at least one dominant allele for spring habit, occur at this locus.Key words: Triticum, complementation, quantitative, vernalization, alleles, multiple.

Genetic and cytogenetic analyses of the A genome of Triticum monococcum. IX. Cytological behaviour, phenotypic characteristics, breeding behaviour, and fertility of primary, double, and triple trisomics

Genome ◽  
1993 ◽  
Vol 36 (3) ◽  
pp. 565-579 ◽  
Author(s):  
N.-S. Kim ◽  
J. Kuspira
Keyword(s):  
Meiotic Chromosome ◽  
Triticum Monococcum ◽  
Low Fertility ◽  
Chromosome Behaviour ◽  
Primary Trisomics ◽  
Breeding Behaviour ◽  
Male Gametes ◽  
A Genome ◽  
Cytogenetic Analyses ◽  
Metaphase I

Cytogenetic studies in Triticum monococcum (2n = 2x = 14, AA) were initiated by generating a series of primary as well as double and triple trisomics from autotriploids derived from crosses between induced autotetraploids and a diploid progenitor. Analysis of meiotic chromosome behaviour revealed that, with the exception of primary trisomics for chromosome 7A, the chromosome present in triple dose in all other trisomics formed either a bivalent plus a univalent or a trivalent (always V shaped) at diakinesis – metaphase I in approximately equal proportions. Trisomics for chromosome 7A formed a bivalent plus a univalent or a trivalent in approximately a 1:2 ratio. About 99% of the anaphase I segregations in all the trisomics were seven to one pole and eight to the other, suggesting that primary trisomics in T. monococcum form n and n + 1 meiotic products in equal proportions. The double trisomics and triple trisomics formed 5 II + 2 III and 4 II + 3 III during metaphase I, respectively. A majority of the secondary meiocytes from the double and triple trisomics possessed unbalanced chromosome numbers. All the trisomics differed phenotypically from their diploid progenitors. Single primary trisomics for chromosomes 3A and 7A produced distinct morphological features on the basis of which they could be distinguished. The phenotypes of the double and triple trisomics deviated to a greater extent from that of diploids than those of the single trisomics. Less than 50% of the progeny of all primary trisomics were trisomics themselves. Trisomic progeny were not produced in diploid female × trisomic male crosses, indicating that functional n + 1 male gametes were not generated. Diploid as well as trisomic progeny were produced in the reciprocal crosses and upon self-fertilization of the trisomics. The average frequency of trisomic progeny was 9.9%. The fertility of primary trisomics ranged from 3.8% in trisomics for chromosome 1A to 40.6% in trisomics for chromosome 2A and was significantly less than that of diploids (99.6%). The breeding behaviour and low fertility of these trisomics make their maintenance and use in cytogenetic analyses difficult.Key words: Triticum monococcum, primary trisomics, double trisomics, triple trisomics, meiotic chromosome behaviour, phenotypes, breeding behaviour, fertility.

Genetic and cytogenetic analyses of the A genome of Triticum monococcum. VII. Telotrisomics and a ditelotetrasomic

Genome ◽  
1992 ◽  
Vol 35 (5) ◽  
pp. 849-854 ◽  
Author(s):  
Nam-Soo Kim ◽  
J. Kuspira
Keyword(s):  
Chromosome Segregation ◽  
Seed Set ◽  
Triticum Monococcum ◽  
Intermediate Phenotype ◽  
Telocentric Chromosome ◽  
Primary Trisomics ◽  
A Genome ◽  
Chromosome 5A ◽  
Cytogenetic Analyses ◽  
Growing Conditions

Telotrisomics (2n = 14 + t) were obtained from primary trisomics for chromosome 5A in Triticum monococcum. Subsequently, a ditelotetrasomic (2n = 14 + 2t) plant was obtained from these telotrisomics. C-banding analysis revealed that the extra telocentric chromosome in these aneuploids consisted of the short arm of chromosome 5A (triplo 5AS). Of 78 meiocytes studied at diakinesis and metaphase I in the telotrisomics, 20 (27.0%), 46 (58.9%), and 12 (14.1%) showed 6 II + 1 III,6 II + 3 I, and 7 II + 1 I configurations, respectively. Although the majority of the cells (84%) at anaphase I (AI) in the telotrisomics showed a 7–8 chromosome segregation, chromosome laggards were also observed. Their frequency (16%) was much higher than in primary trisomics. In a ditelotetrasomic plant, 14, 6, 8, and 4 cells of the 42 meiocytes studied showed 6 II + 1 IV, 7 II + 2 I, 6 II + 1 III + 1 I, and 8 II configurations, respectively. Approximately 62% of the meiocytes at AI in this plant showed an 8–8 chromosome segregation. Compared with primary trisomics and diploids, telotrisomics showed an intermediate phenotype for many of the characters studied. The telotrisomics headed earlier than primary trisomics, but later than diploids. The ditelotetrasomic headed much later than the telotrisomics. The ditelotetrasomic plant also showed very deleterious phenotypes such as slow growth and degeneration of tillers during the later stage of growth. An average of 51.7% of the florets of the telotrisomics exhibited seed set under greenhouse growing conditions. Fertility of the ditelotetrasomic plant on the other hand was very low (2.5%) under the same growing conditions.Key words: Triticum monococcum, C-bands, A genome.

The phylogeny of the polyploid wheats Triticum aestivum (bread wheat) and Triticum turgidum (macaroni wheat)

Genome ◽  
1987 ◽  
Vol 29 (5) ◽  
pp. 722-737 ◽  
Author(s):  
K. Kerby ◽  
J. Kuspira
Keyword(s):  
Triticum Aestivum ◽  
Triticum Turgidum ◽  
Diploid Species ◽  
Triticum Monococcum ◽  
Aegilops Speltoides ◽  
Triticum Urartu ◽  
B Genome ◽  
Aegilops Longissima ◽  
A Genome ◽  
Genome Donors

The phylogeny of the polyploid wheats has been the subject of intense research and speculation during the past 70 years. Various experimental approaches have been employed to ascertain the diploid progenitors of these wheats. The species having donated the D genome to Triticum aestivum has been unequivocally identified as Aegilops squarrosa. On the basis of evidence from many studies, Triticum monococcum has been implicated as the source of the A genome in both Triticum turgidum and Triticum aestivum. However, numerous studies since 1968 have shown that Triticum urartu is very closely related to Triticum monococcum and that it also carries the A genome. These studies have prompted the speculation that Triticum urartu may be the donor of this chromosome set to the polyploid wheats. The donor of the B genome to Triticum turgidum and Triticum aestivum remains equivocal and controversial. Six different diploid species have been implicated as putative B genome donors: Aegilops bicornis, Aegilops longissima, Aegilops searsii, Aegilops sharonensis, Aegilops speltoides, and Triticum urartu. Until recently, evidence presented by different researchers had not permitted an unequivocal identification of the progenitor of the B genome in polyploid wheats. Recent studies, involving all diploid and polyploid wheats and putative B genome donors, lead to the conclusion that Aegilops speltoides and Triticum urartu can be excluded as B genome donors and that Aegilops searsii is the most likely source of this chromosome set. The possibility of the B genome having arisen from an AAAA autotetraploid or having a polyphyletic origin is discussed. Key words: phylogeny; Triticum aestivum; Triticum turgidum; A, B, and D genomes.

Chromosomal organization of a sequence related to LTR-like elements of Ty1-copia retrotransposons in Avena species

Genome ◽  
1999 ◽  
Vol 42 (4) ◽  
pp. 706-713 ◽  
Author(s):  
Concha Linares ◽  
Antonio Serna ◽  
Araceli Fominaya
Keyword(s):  
In Situ Hybridization ◽  
Diploid Species ◽  
D Genome ◽  
Specific Sequence ◽  
Chromosomal Organization ◽  
Intergenomic Translocations ◽  
A Genome ◽  
Slot Blot Analysis ◽  
Copia Retrotransposons

A repetitive sequence, pAs17, was isolated from Avena strigosa (As genome) and characterized. The insert was 646 bp in length and showed 54% AT content. Databank searches revealed its high homology to the long terminal repeat (LTR) sequences of the specific family of Ty1-copia retrotransposons represented by WIS2-1A and Bare. It was also found to be 70% identical to the LTR domain of the WIS2-1A retroelement of wheat and 67% identical to the Bare-1 retroelement of barley. Southern hybridizations of pAs17 to diploid (A or C genomes), tetraploid (AC genomes), and hexaploid (ACD genomes) oat species revealed that it was absent in the C diploid species. Slot-blot analysis suggested that both diploid and tetraploid oat species contained 1.3 × 104 copies, indicating that they are a component of the A-genome chromosomes. The hexaploid species contained 2.4 × 104 copies, indicating that they are a component of both A- and D-genome chromosomes. This was confirmed by fluorescent in situ hybridization analyses using pAs17, two ribosomal sequences, and a C-genome specific sequence as probes. Further, the chromosomes involved in three C-A and three C-D intergenomic translocations in Avena murphyi (AC genomes) and Avena sativa cv. Extra Klock (ACD genomes), respectively, were identified. Based on its physical distribution and Southern hybridization patterns, a parental retrotransposon represented by pAs17 appears to have been active at least once during the evolution of the A genome in species of the Avena genus.Key words: chromosomal organization, in situ hybridization, intergenomic translocations, LTR sequence, oats.

scholarly journals Physical mapping of repetitive oligonucleotides facilitates the establishment of a genome map-based karyotype to identify chromosomal variations in peanut

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Liuyang Fu ◽  
Qian Wang ◽  
Lina Li ◽  
Tao Lang ◽  
Junjia Guo ◽  
...  
Keyword(s):  
In Situ Hybridization ◽  
Physical Mapping ◽  
Tandem Repeats ◽  
Genetic Research ◽  
Diploid Species ◽  
Reference Sequence ◽  
A Genome ◽  
Genome Map ◽  
Chromosomal Variants

Abstract Background Chromosomal variants play important roles in crop breeding and genetic research. The development of single-stranded oligonucleotide (oligo) probes simplifies the process of fluorescence in situ hybridization (FISH) and facilitates chromosomal identification in many species. Genome sequencing provides rich resources for the development of oligo probes. However, little progress has been made in peanut due to the lack of efficient chromosomal markers. Until now, the identification of chromosomal variants in peanut has remained a challenge. Results A total of 114 new oligo probes were developed based on the genome-wide tandem repeats (TRs) identified from the reference sequences of the peanut variety Tifrunner (AABB, 2n = 4x = 40) and the diploid species Arachis ipaensis (BB, 2n = 2x = 20). These oligo probes were classified into 28 types based on their positions and overlapping signals in chromosomes. For each type, a representative oligo was selected and modified with green fluorescein 6-carboxyfluorescein (FAM) or red fluorescein 6-carboxytetramethylrhodamine (TAMRA). Two cocktails, Multiplex #3 and Multiplex #4, were developed by pooling the fluorophore conjugated probes. Multiplex #3 included FAM-modified oligo TIF-439, oligo TIF-185-1, oligo TIF-134-3 and oligo TIF-165. Multiplex #4 included TAMRA-modified oligo Ipa-1162, oligo Ipa-1137, oligo DP-1 and oligo DP-5. Each cocktail enabled the establishment of a genome map-based karyotype after sequential FISH/genomic in situ hybridization (GISH) and in silico mapping. Furthermore, we identified 14 chromosomal variants of the peanut induced by radiation exposure. A total of 28 representative probes were further chromosomally mapped onto the new karyotype. Among the probes, eight were mapped in the secondary constrictions, intercalary and terminal regions; four were B genome-specific; one was chromosome-specific; and the remaining 15 were extensively mapped in the pericentric regions of the chromosomes. Conclusions The development of new oligo probes provides an effective set of tools which can be used to distinguish the various chromosomes of the peanut. Physical mapping by FISH reveals the genomic organization of repetitive oligos in peanut chromosomes. A genome map-based karyotype was established and used for the identification of chromosome variations in peanut following comparisons with their reference sequence positions.

scholarly journals Stripe rust resistance gene Yr34 (synonym Yr48) is located within a distal translocation of Triticum monococcum chromosome 5AmL into common wheat

2021 ◽  
Author(s):  
Shisheng Chen ◽  
Joshua Hegarty ◽  
Tao Shen ◽  
Lei Hua ◽  
Hongna Li ◽  
...  
Keyword(s):  
Resistance Gene ◽  
Common Wheat ◽  
Stripe Rust ◽  
Rust Resistance ◽  
Triticum Monococcum ◽  
Rust Resistance Gene ◽  
Stripe Rust Resistance ◽  
Polyploid Wheat ◽  
Stripe Rust Resistance Gene ◽  
A Genome

AbstractKey messageThe stripe rust resistance geneYr34 was transferred to polyploid wheat chromosome 5AL from T. monococcumand has been used for over two centuries.Wheat stripe (or yellow) rust, caused by Puccinia striiformis f. sp. tritici (Pst), is currently among the most damaging fungal diseases of wheat worldwide. In this study, we report that the stripe rust resistance gene Yr34 (synonym Yr48) is located within a distal segment of the cultivated Triticum monococcum subsp. monococcum chromosome 5AmL translocated to chromosome 5AL in polyploid wheat. The diploid wheat species Triticum monococcum (genome AmAm) is closely related to T. urartu (donor of the A genome to polyploid wheat) and has good levels of resistance against the stripe rust pathogen. When present in hexaploid wheat, the T. monococcum Yr34 resistance gene confers a moderate level of resistance against virulent Pst races present in California and the virulent Chinese race CYR34. In a survey of 1,442 common wheat genotypes, we identified 5AmL translocations of fourteen different lengths in 17.5% of the accessions, with higher frequencies in Europe than in other continents. The old European wheat variety “Mediterranean” was identified as a putative source of this translocation, suggesting that Yr34 has been used for over 200 years. Finally, we designed diagnostic CAPS and sequenced-based markers that will be useful to accelerate the deployment of Yr34 in wheat breeding programs to improve resistance to this devastating pathogen.

scholarly journals Identification of Resistance Determinants for a Promising Antileishmanial Oxaborole Series

2021 ◽  
Vol 9 (7) ◽  
pp. 1408
Author(s):  
Magali Van den Kerkhof ◽  
Philippe Leprohon ◽  
Dorien Mabille ◽  
Sarah Hendrickx ◽  
Lindsay B. Tulloch ◽  
...  
Keyword(s):  
Drug Exposure ◽  
In Vitro Selection ◽  
Selection Procedure ◽  
Cosmid Library ◽  
Neglected Diseases ◽  
Chromosome 2 ◽  
Resistance Determinants ◽  
A Genome

Current treatment options for visceral leishmaniasis have several drawbacks, and clinicians are confronted with an increasing number of treatment failures. To overcome this, the Drugs for Neglected Diseases initiative (DNDi) has invested in the development of novel antileishmanial leads, including a very promising class of oxaboroles. The mode of action/resistance of this series to Leishmania is still unknown and may be important for its further development and implementation. Repeated in vivo drug exposure and an in vitro selection procedure on both extracellular promastigote and intracellular amastigote stages were both unable to select for resistance. The use of specific inhibitors for ABC-transporters could not demonstrate the putative involvement of efflux pumps. Selection experiments and inhibitor studies, therefore, suggest that resistance to oxaboroles may not emerge readily in the field. The selection of a genome-wide cosmid library coupled to next-generation sequencing (Cos-seq) was used to identify resistance determinants and putative targets. This resulted in the identification of a highly enriched cosmid, harboring genes of chromosome 2 that confer a subtly increased resistance to the oxaboroles tested. Moderately enriched cosmids encompassing a region of chromosome 34 contained the cleavage and polyadenylation specificity factor (cpsf) gene, encoding the molecular target of several related benzoxaboroles in other organisms.

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