Spontaneous Reciprocal Translocations Research Articles

Agronomic effects of a reciprocal translocation in a widely grown Spanish barley variety

AbstractA large spontaneous reciprocal translocation is present in a widely grown Spanish barley cv. ‘Albacete’. It has been hypothesized that high popularity of ‘Albacete’ with farmers, particularly in semi-arid areas where barley is grown under rainfed conditions, may be due to the presence of this translocation. Agronomic effects of this translocation were studied at two locations and two growing seasons in a set of 245 doubled haploid lines derived from the F1s of four crosses involving ‘Albacete’. The results have shown a significant positive main effect of the translocation on the thousand kernel weight and a significant environment by translocation interaction for the thousand kernel weight, lodging and tiller number. However, the results do not support the hypothesis that this chromosomal structural change alone provides an increased adaptation to low-yielding sites.

Detection of Spontaneous Reciprocal Translocation Lines in Tunisian Barley

Detection of Spontaneous Reciprocal Translocation Lines in Tunisian Barley

C-banding analysis on wild Emmer (Triticum dicoccoides Körn) strains with and without spontaneous reciprocal translocations

C-banding polymorphism was analyzed in eight strains of wild Emmer, Triticum dicoccoides Körn, which included six translocation homozygotes reported previously. Polymorphisms were detected in all of the strains examined, and the breakpoints of five spontaneous translocations were successfully identified by C-bands. Of the eight breakpoints that could be precisely identified, one was located in the centromeric region while the remaining seven were located in proximal to distal euchromatic regions. The two breakpoints of one translocation could only be approximately localized to proximal regions due to the scarcity of C-bands. The present results are in contrast with those observed on T. araraticum, another wild tetraploid wheat belonging to the Timopheevi group, in which most of the breakpoints were located in centromeric regions. In T. dicoccoides, the six translocation chromosome types were derived from the standard karyotype primarily by a mechanism other than centric breakage-fusion.

C-banding analysis on wild Emmer (Triticum dicoccoides K�rn) strains with and without spontaneous reciprocal translocations

C-banding analysis on wild Emmer (Triticum dicoccoides K�rn) strains with and without spontaneous reciprocal translocations

Meiotic Configuration of a Cultivated Rye Collected from China.

Meiotic configuration of a cultivated rye with B chromosomes from China was characterized. Plants with two B chromosomes formed the highest frequency of a bivalent of B chromosomes while the multivalent formation of B chromosomes in plants with four B chromosomes was relatively high. The existence of B chromosomes had negligible effect on the mean chiasma frequency of A chromosomes. Spontaneous reciprocal translocations of A chromosomes were also detected in two out of 40 plants examined with the length of chromosome segment involved in translocations assumed to be different in the two translocation heterozygotes.

Chromosome Studies on Capsicum (Solanaceae) I. Karyotype Analysis in C. Chacoense

The somatic chromosomes and karyotypes of two Argentine populations of Capsicum chacoense A. T. Hunz. have been studied, both of which have 2n=24. The karyotypes are symmetrical, being composed of 11 m paris + one st pair; two pairs of chromosomes are satellied: pairs 1 and 12 in one population and pairs 11 and 12 in the other one. A heteromorphic pair of satellited chromosomes in one individual suggests a spontaneous reciprocal translocation. Results are compared with previous reports for the species and genus. Data show an intraspecific karyotype variation.

Regional assignments of NP and MPI on chromosome 7 in pig, Sus scrofa

Fibroblasts from a pig with a spontaneous reciprocal translocation involving chromosome 7, were used to prepare a set of pig-mouse somatic cell hybrids. The isozyme analysis strongly indicated that in pigs, the NP (nucleoside phosphorylase) gene is located on the distal part of the long arm of chromosome 7, (q21----qter), while the MPI (mannose phosphate isomerase) gene is in the region q21----pter. This confirmed previously reported chromosomal assignment of these genes in pigs and that this synteny has been evolutionarily conserved in several different animal species.

Spontaneous chromosomal rearrangements in cultivated and wild barleys

Four of 1,240 cultivated barley lines collected from different regions of the world and 3 of 120 lines of wild barley, Hordeum spontaneum C. Koch, carry spontaneous reciprocal translocations. Break-point positions and rearrangements in the interchanged chromosomes have been examined by both test crosses and Giemsa banding techniques. The four translocation lines in cultivated barley were all of Ethiopian origin and have the same translocation involving chromosomes 2 and 4. The breakpoints are at the centromeres of both chromosomes, resulting in interchanged chromosomes 2S+4S and 2L+4L (S=short arm, L=long arm). A wild barley line, Spont.II, also has translocated chromosomes 2 and 4 which are broken at the centromeres. The resultant chromosomes are, however, 2S+4L and 2L+4S. Another wild barley line, Spont.S-4, has interchanged chromosomes with breakpoints in the short arm of chromosome 3 and the long arm of chromosome 7. In addition, this line has a paracentric inversion in the short arm of chromosome 7 that includes a part of nucleolar constriction, resulting in two tandemly arranged nucleolar constrictions. The third wild barley line, Spont.S-7, has interchanged chromosomes with breakpoints in the long arms of both chromosomes 3 and 6. The translocated chromosome 3 is metacentric and the translocated chromosome 6 has a long arm similar in length to the long arm of chromosome 7.

Spontaneous reciprocal translocations in cultivated form of Emmer wheat.

Twenty-one F1 hybrids among fourteen varieties or cultivars of cultivated form of Emmer wheat were studied with respect to chromosome pairing at MI of PMC′s, and four chromosome types were determined according to the reciprocal translocations detected. In relation to LD 222 type that was recognized as a standard, Ethiopicum type had a reciprocal translocation between 2A and 4A, and two translocations among three chromosomes, i.e. 4A-2A:2A-2B, were carried by Abyssinicum type. Liguliforme type had two different translocations, the one being between 7A and 5B, but the other unidentified.

The Genus Collinsia. XXXI. Cytogenetics of a Spontaneous Reciprocal Translocation in C. parryi

The first spontaneous reciprocal translocation detected in a wild population of Collinsia was found in C. parryi. The interchange complex occurred as a ring or chain of four chromosomes at metaphase I and displayed an alternate or adjacent configuration in approximately equal frequencies at this stage. Crosses involving plants with an interchange complex gave progeny with only bivalents or an interchange complex in approximately equal frequencies. These observations suggest that the breaks probably occurred within the intervening segment of nonhomologous chromosomes and close to one of the chiasma-forming segments in each chromosome arm.

Redundant segments inZea mays detected by translocations of monoploid origin

Twenty-two independently occurring spontaneous reciprocal translocations were isolated from monoploid X diploid crosses in maize and their breakpoints were determined. As 12 of the translocations involved the same two chromosomes and had breakpoints at approximately the same positions (6L. 2–3, 7L. 2–3) and two other translocations appeared to be identical with breakpoints at 2L. 9, 6L. 4, 14 of the 22 translocations probably arose by crossing over within duplicate segments of nonhomologous chromosomes. Thus, at least part of the bivalents seen at diakinesis and chromatid bridges seen at anaphase I in monoploid plants appear to be generated by recombination between redundant chromosome segments. The other eight translocations each occurred once. Because our evidence indicates that recombination between nonhomologous illegitimately synapsed chromosome segments does not occur in maize, these were probably also produced by recombination between redundant segments. If one assumes that their breakpoints also mark regions of interchromosomal redundancy, other conclusions can be reached: A) corn does not contain detectable homoeologous chromosomes, thus it is precently a true diploid, and B) as exchanges giving rise to translocations did not occur in the centromeres or proximal heterochromatin, these regions either do not possess redundancy or are rarely involved in chiasma formation. Furthermore, the duplicated segments in the genome giving rise to translocations in haploid microsporocytes probably have the same serial order with respect to the centromere.

Spontaneous Reciprocal Translocation during Megasporogenesis of Maize Haploids

IN the course of an investigation of haploidy in maize, a number of haploids were pollinated by normal diploid males. The progenies were grown to anthesis and classified for pollen abortion, with the thought that some of them would be monosomic, that is, would arise from n-1 eggs. An F1 plant was found to be semi-sterile (male) and was self-pollinated and outcrossed with a normal female. Subsequent examination of the selfed and outcrossed progenies revealed that the original semi-sterile F1 plant was heterozygous for a reciprocal translocation. The finding agrees with earlier observations in which recovery of reciprocal translocation from haploids of Triticum vulgare1 and of Sorghum vulgare2 had been made.

Strukturheterozygotie beiVicia faba

The karyotypes and the meiotic behaviour of two spontaneous reciprocal translocations and one pericentric inversion are described. One of these translocations was characterized by chiasma-formation in the interstitial-segments, the other was not. The types of orientation and distribution of the chromosomes from the chain-configurations in meta-anaphase I are specified, compared mutually and with those of translocation rings and chains in maize and the similarities and differences are pointed out. In the range of the heterozygous pericentric inversion there was no pairing in meiotic prophase and therefore no chiasma formation and sterility. It will be tried to cross especially one of the translocations with the inversion-type in order to rebuild the karyotype ofVicia faba. In this case it would be possible to distinguish between all five pairs of small chromosomes according to their morphological structure, a possibility very important in localizing chromosome aberrations on the chromosomes ofVicia faba.