Putative diploid ancestors of 80-chromosome Glycine tabacina

Genome ◽  
1992 ◽  
Vol 35 (1) ◽  
pp. 140-146 ◽  
Author(s):  
R. J. Singh ◽  
K. P. Kollipara ◽  
F. Ahmad ◽  
T. Hymowitz

The objective of this study was to discover the diploid progenitors of 80-chromosome Glycine tabacina with adventitious roots (WAR) and no adventitious roots (NAR). Three synthetic amphiploids were obtained by somatic chromosome doubling. These were (i) (G. latifolia, 2n = 40, genome B1B1,) × (G. microphylla, 2n = 40, genome BB) = F1(2n = 40, genome BB1) – 0.1% colchicine treatment (CT) – 2n = 80, genome BBB1B1; (ii) (G. canescens, 2n = 40, genome AA) × G. microphylla, 2n = 40, genome BB) = F1 (2n = 40, genome AB) – (CT) – 2n = 80, genome AABB; (iii) (G. latifolia, 2n = 40, B1B1) × G. canescens, 2n = 40, AA) = F1 (2n = 40, genome AB1) – (CT) – 2n = 80, genome AAB1B1. The segmental allotetraploid BBB1B1 was morphologically similar to the 80-chromosome G. tabacina (WAR), but meiotic pairing data in F1 hybrids did not support the complete genomic affinity. Despite normal diploid-like meiosis in allotetraploids AABB and AAB1B1, AABB was completely fertile, while pod set in AAB1B1 was very sparse. Morphologically, allotetraploid AABB was indistinguishable from the 80-chromosome G. tabacina (NAR) but in their F1 hybrids, the range of univalents at metaphase I was wide (4–44). The allotetraploid AAB1B1 did not morphologically resemble the 80-chromosome G. tabacina (NAR). However, the F1 hybrid of AABB × AAB1B1 showed normal meiosis with an average chromosome association (range) of 1.7 I (0–4) + 39.2 II (38–40). Based on this information, we cannot correctly deduce the diploid progenitor species of the 80-chromosome G. tabacina (NAR). The lack of exact genome homology may be attributed to the geographical isolation, natural mutation, and growing environmental conditions since the inception of 80-chromosome G. tabacina. Thus, it is logical to suggest that the 80-chromosome G. tabacina (NAR) is a complex, probably synthesized from A genome (G. canescens, G. clandestina, G. argyrea, G. tomentella D4 isozyme group) and B genome (G. latifolia, G. microphylla, G. tabacina) species, and the 80-chromosome G. tabacina (WAR) complex was evolved through segmental allopolyploidy from the B genome species.Key words: Glycine spp., allopolyploidy, colchicine, genome, intra- and inter-specific hybridization, polyploid complex.

Genome ◽  
1988 ◽  
Vol 30 (2) ◽  
pp. 166-176 ◽  
Author(s):  
R. J. Singh ◽  
K. P. Kollipara ◽  
T. Hymowitz

The present study furnishes information about the current status of knowledge concerning the genomic relationships among 9 of the 12 wild perennial species (2n = 40) of the subgenus Glycine. Crossability rate, hybrid inviability, and meiotic pairing in intra- and inter-specific F1 hybrids revealed that genomically similar species, though morphologically distinct, crossed readily to produce hybrid progeny that were vigorous, fertile, and normal in meiotic pairing (20 bivalents at metaphase I). However, a chromatin bridge and acentric fragment were recorded in certain hybrid combinations, suggesting that the evolutionary divergence in genomically similar species occurred because of paracentric inversions. In contrast, crosses between genomically dissimilar species set pods that often aborted, showed hybrid weakness, seedling and vegetative lethality, seed inviability, and complete sterility. The sterility was attributed to disturbed meiotic pairing. It is obvious from this study that A-genome species such as G. canescens (AA) G. clandestina (intermediate pod, A1A1, and long pod, A2A2), and G. argyrea (A3A3), and B-genome species such as G. microphylla (BB), G. latifolia (B1B1), and G. tabacina (B2B2) predominate in the subgenus Glycine. Glycine cyrtoloba (CC) showed stronger genome homology to B-genome species than to A-genome species. Likewise, G. tomentella (DD) appeared to be more closely associated with A-genome species than to B-genome species. Although tomentellas with 38 and 40 chromosomes were indistinguishable morphologically, they differed genomically. Therefore, genome symbol EE was assigned to the 38-chromosome G. tomentella. Glycine falcata (FF) was found to be the most unusual species because it showed negligible chromosome homology with A- and B-genome species and did not set pods when cross-pollinated by C-, D-, and E-genome species.Key words: Glycine spp., genome, hybridization.


Genome ◽  
1989 ◽  
Vol 32 (2) ◽  
pp. 169-172 ◽  
Author(s):  
J. Orellana ◽  
J. F. Vazquez ◽  
J. M. Carrillo

Using C-banding, homologous and homoeologous meiotic pairing between wheat (AB), rye (R), and Aegilops caudata (C) genomes were estimated at meiotic metaphase I in trigeneric hybrids (AABBRC; 2n = 6x = 42). In all hybrids, the C-genome chromosomes pair homoeologously only with chromosomes of the A genome, but not with chromosomes of the B genome or R genome. The A – C pairing was restricted to trivalents (0.15 per cell), each composed of two A-genome and one C-genome chromosomes. These preliminary data suggest that the C genome of Ae. caudata is probably more closely related to the A genome than to the B genome of wheat.Key words: trigeneric hybrid, wheat, rye, Aegilops, genome analysis, meiosis.


1991 ◽  
Vol 18 (1) ◽  
pp. 22-26 ◽  
Author(s):  
Charles E. Simpson

Abstract Four pathways for gene introgression into Arachis hypogaea L. were studied. Two “hexaploid routes” involved direct crosses of diploid Arachis species and diploid species hybrids with A. hypogaea (Pathways 1 and 2, respectively) and were followed by chromosome doubling with colchicine. A third pathway, a tetraploid route, involved chromosome doubling of a diploid hybrid before crossing with A. hypogaea. These first three routes involved only the A genome species, and all were unsuccessful because of lack of fertility. The fourth pathway, also a tetraploid route, utilized the B genome A. batizocoi Krap. et Greg. as a bridge species and brought about a successful (fertile) introgression. Genes from A. cardenasii Krap. et Greg. nom. nud. and A. chacoensis Krap et Greg. nom. nud. were combined into a hybrid and incorporated into A. hypogaea by using the B genome bridge species. Introgression of additional characters from these and other species through this pathway should be possible.


1972 ◽  
Vol 14 (3) ◽  
pp. 645-654 ◽  
Author(s):  
Tibor Rajhathy ◽  
B. R. Baum

A new diploid species of oat from Syria, named Avena damascena Rajhathy et Baum, is described. It has some macro- and micromorphological similarities to A. wiestii and A. prostrata, both diploids, and to tetraploid A. barbata. It differs from one or the other of them in its lemma tips, lodicules, epiblast and in the unique structure of the cuticle on the glumes. Avena damascena has a distinct symmetrical karyotype, designated Ad. The karyotype of A. prostrata is designated Ap. Avena damascena is isolated from A. prostrata by hybrid sterility and from the other diploids by cross-incompatibility. Avena damascena and A. prostrata are considered relicts of a common population because they retain a high degree of genome homology. Their chromosomes differ by two interdependent interchange complexes which led to a pollen sterility. Genome relationships in the A genome group of diploids are briefly discussed in terms of meiotic pairing patterns and karyotypes.


Genetics ◽  
1998 ◽  
Vol 149 (4) ◽  
pp. 2007-2023 ◽  
Author(s):  
Marion S Röder ◽  
Victor Korzun ◽  
Katja Wendehake ◽  
Jens Plaschke ◽  
Marie-Hélène Tixier ◽  
...  

Abstract Hexaploid bread wheat (Triticum aestivum L. em. Thell) is one of the world's most important crop plants and displays a very low level of intraspecific polymorphism. We report the development of highly polymorphic microsatellite markers using procedures optimized for the large wheat genome. The isolation of microsatellite-containing clones from hypomethylated regions of the wheat genome increased the proportion of useful markers almost twofold. The majority (80%) of primer sets developed are genome-specific and detect only a single locus in one of the three genomes of bread wheat (A, B, or D). Only 20% of the markers detect more than one locus. A total of 279 loci amplified by 230 primer sets were placed onto a genetic framework map composed of RFLPs previously mapped in the reference population of the International Triticeae Mapping Initiative (ITMI) Opata 85 × W7984. Sixty-five microsatellites were mapped at a LOD >2.5, and 214 microsatellites were assigned to the most likely intervals. Ninety-three loci were mapped to the A genome, 115 to the B genome, and 71 to the D genome. The markers are randomly distributed along the linkage map, with clustering in several centromeric regions.


Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 112
Author(s):  
Songshan Liu ◽  
Chenxing Zhang ◽  
Weicong Yang ◽  
Xiang Li ◽  
Lu Hou ◽  
...  

Polyploid breeding is an important strategy for tree improvement because polyploid individuals typically show superior traits, such as improved growth, stress resistance, and superior fruit quality. Artificial induction of chromosome doubling of female gametes is an effective approach to obtain triploid progeny. However, no triploid fruit tree cultivars have been developed using this approach. The objective of this study was to explore the utility of chromosome doubling in female gametes of ‘Maya’ jujube to produce triploid individuals. The temporal relationship between flower bud morphology and the megaspore meiotic stage was studied to guide the optimal timing of colchicine treatment. Colchicine solution was applied to bearing shoots of mature ‘Maya’ jujube trees in a field experiment using two treatment methods (improved cotton leaching and injection method) and three concentrations (0.3%, 0.4%, and 0.5%). The water transport rate of ‘Maya’ jujube shoots was studied using dye solution to judge the effectiveness and timing of the colchicine treatment methods. Two triploids were identified among the progenies from the colchicine-treated shoots. The highest efficiency of triploid production was 3.3% when flower buds of diameter 1.76–2.12 mm were treated with 0.3% colchicine solution for 4 h using an improved cotton leaching method. The ground diameter, plant thorn length, leaf width, leaf area, stomatal length, stomatal width, chlorophyll content, and photosynthetic parameters of one triploid individual were significantly higher than those of diploids of identical parentage at 18 months old. Thus, induction of 2n megaspores is an effective approach to generate triploid jujube. These results are expected to promote and accelerate triploid breeding in fruit trees.


Genetics ◽  
1998 ◽  
Vol 150 (3) ◽  
pp. 1199-1208 ◽  
Author(s):  
Juan M Vega ◽  
Moshe Feldman

Abstract The analysis of the pattern of isochromosome pairing allows one to distinguish factors affecting presynaptic alignment of homologous chromosomes from those affecting synapsis and crossing-over. Because the two homologous arms in an isochromosome are invariably associated by a common centromere, the suppression of pairing between these arms (intrachromosome pairing) would indicate that synaptic or postsynaptic events were impaired. In contrast, the suppression of pairing between an isochromosome and its homologous chromosome (interchromosome pairing), without affecting intrachromosome pairing, would suggest that homologous presynaptic alignment was impaired. We used such an isochromosome system to determine which of the processes associated with chromosome pairing was affected by the Ph1 gene of common wheat—the main gene that restricts pairing to homologues. Ph1 reduced the frequency of interchromosome pairing without affecting intrachromosome pairing. In contrast, intrachromosome pairing was strongly reduced in the absence of the synaptic gene Syn-B1. Premeiotic colchicine treatment, which drastically decreased pairing of conventional chromosomes, reduced interchromosome but not intrachromosome pairing. The results support the hypothesis that premeiotic alignment is a necessary stage for the regularity of meiotic pairing and that Ph1 relaxes this alignment. We suggest that Ph1 acts on premeiotic alignment of homologues and homeologues as a means of ensuring diploid-like meiotic behavior in polyploid wheat.


2021 ◽  
Author(s):  
Nicolas Pompidor ◽  
Carine Charron ◽  
Catherine Hervouet ◽  
Stéphanie Bocs ◽  
Gaëtan Droc ◽  
...  

Abstract Background and Aims Modern sugarcane cultivars (Saccharum spp.) are high polyploids, aneuploids (2n = ~12x = ~120) derived from interspecific hybridizations between the domesticated sweet species Saccharum officinarum and the wild species S. spontaneum. Methods To analyse the architecture and origin of such a complex genome, we analysed the sequences of all 12 hom(oe)ologous haplotypes (BAC clones) from two distinct genomic regions of a typical modern cultivar, as well as the corresponding sequence in Miscanthus sinense and Sorghum bicolor, and monitored their distribution among representatives of the Saccharum genus. Key Results The diversity observed among haplotypes suggested the existence of three founding genomes (A, B, C) in modern cultivars, which diverged between 0.8 and 1.3 Mya. Two genomes (A, B) were contributed by S. officinarum; these were also found in its wild presumed ancestor S. robustum, and one genome (C) was contributed by S. spontaneum. These results suggest that S. officinarum and S. robustum are derived from interspecific hybridization between two unknown ancestors (A and B genomes). The A genome contributed most haplotypes (nine or ten) while the B and C genomes contributed one or two haplotypes in the regions analysed of this typical modern cultivar. Interspecific hybridizations likely involved accessions or gametes with distinct ploidy levels and/or were followed by a series of backcrosses with the A genome. The three founding genomes were found in all S. barberi, S. sinense and modern cultivars analysed. None of the analysed accessions contained only the A genome or the B genome, suggesting that representatives of these founding genomes remain to be discovered. Conclusions This evolutionary model, which combines interspecificity and high polyploidy, can explain the variable chromosome pairing affinity observed in Saccharum. It represents a major revision of the understanding of Saccharum diversity.


2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Kai Zhou ◽  
Paige Fleet ◽  
Eviatar Nevo ◽  
Xinquan Zhang ◽  
Genlou Sun

2020 ◽  
Vol 80 (01) ◽  
Author(s):  
Arshpreet Kaur ◽  
Rahul Kapoor ◽  
Yogesh Vikal ◽  
Anu Kalia

We report the production of hexaploid plants of interspecific hybrids of Pennisetum, with the ultimate aim to improve the biomass yield, drought tolerance and multicut behaviour of this genus. Chromosome doubling was achieved with the application of colchicine at three different concentrations (0.05, 0.1 and 0.2%) for two time durations (12 and 24 hours). The root slips and stem cuttings of interspecific hybrids were used for treatment and the root slips were found to be more efficient. The preliminary screening to select the putative hexaploid plant was done based on stomatal frequency and morphology. Plants containing significantly lower stomatal frequency and larger stomata size were selected for further analysis by chromosome counting. This experiment confirmed that 0.1% concentration of colchicine treatment to root slips for 24 hours was more effective to induce the amphiploids in Pennisetum.


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