Transfer of Hessian fly resistance from ‘Chaupon’ rye to hexaploid wheat via a 2BS/2RL wheat-rye chromosome translocation

Summary Four wheat-rye lines derived from a cross between hexaploid wheat ND 7532 and Chaupon rye were homogeneous for resistance to biotype L of the Hessian fly,Mayetiola destructor. Because the wheat parent was susceptible and the rye parent was resistant to larval feeding, resistance was derived from rye. Resistance of Chaupon and the wheat-rye lines was expressed as larval antibiosis. First-instar larvae died after feeding on plants. Chromosomal analyses using C- and N-banding techniques were performed on plants of each line to identify genomes and structural changes of chromosomes. Results showed that two of the resistant lines were chromosome addition lines carrying either the complete rye chromosome,2R, or only the long arm of2R. The other two resistant lines were identified as being2BS/ 2RL wheat-rye translocation lines. It was concluded, therefore, that the long arm of rye chromosome2R carries a gene or gene complex that conditions antibiosis to Hessian fly larvae and, in the2BS/2RL translocation lines, this rye chromatin is cytologically stable and can be used directly in wheat breeding programs.Cooperative investigations of the Kansas Agricultural Experiment Station, Departments of Agronomy, Entomology, and Plant Pathology, Wheat Genetics Resource Center, and the U.S. Department of Agriculture, Agricultural Research Service, Kansas State University. Contribution No. 89-507-JPartly supported by the Deutsche Forschungsgemeinschaft     

Identification of a 4A/7R and a 7B/4R wheat-rye chromosome translocation

Summary By producing chromosome substitutions with Imperial rye chromosomes 4R (C) and 7R (D) in the wheat cultivar Chinese Spring two spontaneous translocation lines were obtained. One involves segments of wheat chromosome 4A and rye chromosome 7R, the other involves portions of wheat chromosome 7B and rye chromosome 4R     

Meiotic pairing and alpha-amylase phenotype in a 5B/5Rm Triticum aestivum — Secale montanum translocation line in common wheat

Summary A 5BS/5R^mS translocation chromosome spontaneously recovered from a Chinese Spring — Secale montanum wheat-rye telocentric 5R^mS addition line has been identified and cytologically studied using C-banding in somatic and meiotic cells. Analysis of the translocated chromosome showed that a terminal segment of the short arm of 5B had been replaced by a short terminal region of chromosome arm 5R^mS. The translocation led to the deletion of the genetic system promoting pairing located in 5BS, which is slightly compensated for when doses of 5R^mS are increased, indicating homoeology to wheat chromosome 5BS. The -amylase phenotype in 5B/5R^m translocated material was studied and found to be identical to that of ditelocentric line 5BL of Chinese Spring. An effect on the -amylase activity was detected as a result of the removal of the terminal region of 5BS, perhaps as a consequence of variation in dormancy period duration.     

Identification of a 1B/1R wheat-rye chromosome translocation

Summary The common wheat selection 79-4045 was identified as a wheat-rye 1B/1R chromosome translocation line, by means of C-banding patterns and test cross with Chinese Spring double-ditelosomic line. The translocation chromosome consisted of the long arm of wheat chromosome 1B, including its centromere, and the short arm of rye chromosome 1R or tis portion.     

Evidence for wheat-rye nucleolar competition (amphiplasty) in triticale by silver-staining procedure

Summary Amphiplasty in hexaploid triticale, the artificial amphiploid of tetraploid wheat and diploid rye, is analyzed for the first time using a modified, highly reproducible, silver-staining procedure. A comparative analysis of metaphase somatic cells by phase contrast, C-banding and silver-staining of the hexaploid triticale cv. Cachirulo and its parents, namely, the tetraploid durum wheat cv. Enano de Andujar and the diploid rye cv. Petkus has been made. Two silver-stained nucleolar organizer regions (Ag-NORs) (the chromosome pair 1 R) are observed in all rye plants analyzed, whereas four Ag-NORs (chromosome pairs 1 B and 6 B) are found both in the tetraploid wheat parent and in the triticale. The rye Ag-NORs are absent in the triticale. Since the Agstaining reaction of NORs can be considered as an indication for genetic activity, the silver procedure can be used to visualize gene functionality at the rDNA sites with conventional light microscopy and, consequently, the modified Ag-staining method described can be very useful in analyzing the amphiplasty phenomenon in natural or artificial hybrid combinations and derivatives in the Triticum group and its relatives.     

Chromosomal location of esterase,peroxidase and phosphoglucomutase isozyme structural genes in cultivated rye (Secale cereale L.)

Summary Isoelectric focusing of esterase (EST), peroxidase (PRX), and phosphoglucomutase (PGM) isozymes in Chinese Spring wheat, Imperial rye and several Chinese Spring/Imperial and Holdfast/King II addition, translocation and substitution lines revealed the chromosomal location of nine Est loci previously described and of one Prx and Pgm locus. Loci Est1, Est2, Est3, Est5, Est6 and Est7 were found on chromosome arm 5RL, Est8 and Est9 on chromosome 6R in Imperial rye, and the Est10 locus on chromosome arm 4RL in Imperial rye and King II rye. A discrepancy was found between the chromosomal location of the Prx locus in Imperial where chromosome 2R was responsible for the expression of the peroxidase enzyme, and King II with chromosome 1R carrying the Prx gene. As a possible explanation, the occurrence of translocation events during the production of wheat/rye aneuploid lines is discussed. The rye Pgm locus could be associated with chromosome 4RS in Imperial and King II rye. Except for the location of Est loci on chromosome 5RL, the results reported in this paper lend further evidence for the assumed homoeology relationships between the chromosomes of Triticinae and for the conservation of gene synteny groups during the evolution of the Triticeae tribe.     

Identification of a complete set of isogenic wheat/rye D-genome substitution lines by means of Giemsa C-banding

Summary A complete set of isogenic wheat/rye D-genome substitutions were produced by crossing an inbred line of spring rye Secale cereale L. cv. Prolific to a tetraploid wheat, the A-and B-genomes of which had previously been extracted from hexaploid wheat, Triticum aestivum L. em Thell. cv. Thatcher. After chromosome doubling, the derived hexaploid triticale (x Triticosecale Wittmack) was backcrossed to 6x Thatcher and selection for wheat/rye substitution lines was carried out in BCF₃ to BCF₆ families by using Giemsa C-banding. Five fertile disomic wheat/rye D-genome substitution lines were obtained and their chromosomal constitution was determined to be 1D/1R, 2D/2R, 7D/4R, 6D/6R, 7D/7R. The two remaining 3R and 5R substitutions are at the moment in a monosomic condition. Another 1D/7R substitution was detected but this plant was very weak and sterile, indicating that only substitutions between homoeologous chromosomes result in fertile, vigorous plants. Furthermore, many rye telocentrics as well as rye-rye and rye-wheat translocations were selected. Since all lines selected in this program share the same genetic background of Thatcher wheat, genetic heterogeneity is excluded. The material is very useful, therefore, for analyzing the effects of different rye chromosomes or chromosome segments in an otherwise homozygous background.Contribution No. 797     

Molecular cytogenetic analysis of radiation-induced wheat-rye terminal and intercalary chromosomal translocations and the detection of rye chromatin specifying resistance to Hessian fly

Radiation-induced wheat-rye chromosome translocation lines resistant to Hessian fly, Mayetiola destructor (say), were analyzed by in situ hybridization using total genomic and highly repetitive rye DNA probes pSc119 and pSc74. In situ hybridization analysis revealed the exact locations of the translocation breakpoints and allowed the estimation of the sizes of the transferred rye segments. T6BS·6BL-6RL and T4BS· 4BL-6RL are terminal translocations with either most of the complete long arm of rye chromosome 6R or only the distal 57% of the 6RL arm attached to the long arms of wheat chromosomes 6B and 4B, respectively. The breakpoint in T6BS·6BL-6RL is located at a fraction length (FL) of 0.11 in the long arm of T6BS 6BL-6RL and at FL 0.46 in the long arm of T4BS·4BL-6RL. Ti4AS·4AL-6RL-4AL is an intercalary translocation with the breakpoint located at FL 0.06 in the long arm of wheat chromosome 4A. The inserted 6RL segment, with the Hessian fly resistance gene, has a size of 0.7 m, and is the smallest and, so far, the first radiation-induced intercalary translocation identified in wheat.by R. Apples     

Genetic control of 6-phosphogluconate dehydrogenase (6-PGD) isozymes in cultivated wheat and rye

Summary The 6-phosphogluconate dehydrogenase (6-PGD) zymogram phenotypes of wheat, rye and their aneuploid derivatives were determined. Two genes involved in the production of 6-PGD isozymes were located on chromosome arms CRL (4 RL) and FRL (6 RL) of Imperial rye. On the basis of differential interactions between wheat and rye chromosomes, evidence was obtained that genes located on chromosomes 6 A, 6 BL and 7 BL control 6-PGD isozyme activities in Chinese Spring wheat. The wheat and rye 6-PGD zymogram phenotypes were indicative of homoeologous relationships between rye chromosome 6 RL to wheat chromosomes of group 6, and rye chromosome 4 RL to wheat chromosomes of group 7.     

Study of androgenetic performance and molecular characterisation of a set of wheat-rye addition lines

Rye chromosomes of wheat-rye addition lines were successfully identified by means of an RFLP analysis with 30 probes. Our results are in agreement with previous cytological data concerning the identity of lines F (+1R), D (+2R), C (+3R), A (+4R), E (+5R) and B (+7R). Two categories of chromosomal rearrangements have been distinguished, namely: (1) deletions: the current line D possesses a chromosome 2R deleted on its short arm and the line G a chromosome 3R deleted on its long arm; we have also noticed a deletion on the long arm of wheat chromosome 1A in line F61; and (2) evolutionary reciprocal translocations in rye relative to wheat which have been previously mentioned in the literature. The anther culture response of the different lines was studied. A significant difference between FEC 28 and the addition lines was observed for embryo production and plant regeneration. It appears that genes located on S 10 chromosome arm 3RL and on FEC 28 chromosome arm 1AL increase embryo frequency whereas gene(s) located on S 10 chromosome 5R reduce(s) it. Plant regeneration results suggest that genes increasing regeneration ability and green-plant frequency are located on S 10 chromosome 4R. The long arm of chromosome 1A seems to be involved positively in green-plant regeneration whereas chromosomes 1R and 3R limit plant regeneration.     

Analysis of the effect of rye chromosomes 4R, 6R and telomeric heterochromatin on 7R on homologous chromosome pairing in pentaploid hybrids (AABBR,AABBD)

Summary Meiotic pairing in Triticum turgidum cv. Ma (4x) with a mean chiasmata frequency of 27.16 per cell was compared with chiasmata frequencies in its hybrids with several triticale strains, Chinese Spring wheat and its addition lines for Imperial rye chromosomes 4R and 6R. In hybrids between Ma and x Triticosecale cv. Rosner the chiasmata frequency was marginally reduced by an average of 1.25%, by 8.8% in hybrids with x Triticosecale cv. DRIRA HH and by 6.7% with DRIRA EE (lacking 90% telomeric heterochromatin from chromosome arm 7RL). In pentaploid hybrids between Ma and T. aestivum cv. Chinese Spring the reduction was an average of 10.30%, while addition lines with rye chromosome 6R reduced chiasmata frequencies by an average of 7.4% and rye addition line for 4R showed the greatest depression in chiasmata frequency in hybrids by a 25.04% reduction. An interchange difference involving long chromosome segments was observed between Ma and Rosner.Contribution No. 819 Ottawa Research Station     

Identification of the chromosomes of the rye translocation tester set

Summary Intercrossing the Wageningen translocation tester set of rye and the series of Imperial rye additions to Chinese Spring wheat of Sears yielded 29 chromosome disomic translocation hybrids. Observation of trivalents led to the identification of the chromosomes of the tester set in terms of the terminology system used in the Triticinae. The analysis was complicated by very low chiasma frequencies in some short chromosome segments in the hybrids. Nevertheless, it could be safely concluded that 1R=VII; 2R=III; 3R=II; 4R=IV; 5R=VI; 6R=V; 7R=I, which deviates slightly from previous classifications based on other methods.     

Comparative RFLP maps of the homoeologous group-2 chromosomes of wheat,rye and barley

Summary Genetic maps of the homoeologous group-2 chromosomes were constructed, comprising 114 loci in wheat and 34 loci in rye. These include the genes coding for sucrose synthase, sedoheptulose-1,7-bisphosphatase, a bZIP protein (EmBP-1), a peroxidase and an abscisic acid-induced protein (#7). Overall, gene orders are highly conserved in the genomes of wheat, barley and rye, except for the distal ends of chromosome arms 2BS and 2RS, which are involved in interchromosomal, probably evolutionary, translocations. Clustering of loci in the centromeric regions of the maps, resulting from the concentration of recombination events in the distal chromosomal regions, is observed in wheat and rye, but not in barley. Furthermore, loci for which homoeoloci can be detected in rye and barley tend to lie in the centromeric regions of the maps, while non-homoeologous and wheat-specific loci tend to be more evenly distributed over the genetic maps. Mapping of the group-2 chromosomes in the intervarietal Timgalen x RL4137 cross revealed that the T. timopheevi chromosome segment introgressed into chromosome 2B in Timgalen is preferentially transmitted. Recombination is also greatly reduced in that segment.     

The chromosomal locations and linkage relationships of the structural genes for the prolamin storage proteins (secalins) of rye

Summary Rye secalins are a polymorphic mixture of polypeptides which are classified into four major groups. Previous studies have shown that the structural genes for two of the groups (the -secalins and 40K -secalins) are located on the short arm of chromosome 1R and those for a third group (the high molecular weight secalins) on the long arm of the same chromosome. Analysis of F₂ grain from crosses between inbred lines of S. cereale shows that the structural genes for the -secalins (designated Sec 1) and the high molecular weight secalins (designated Sec 3) are loosely linked (40.8 ±3.76% recombination, 57.4 ± 11.30 cM). Analysis of wheat rye addition lines shows that the structural genes for the 75K -secalins are present on chromosome 2R. This locus is provisionally designated Sec 2. These genes are probably derived from those for the 40K -secalins by duplication, divergence and translocation. Analysis of secalin fractions from wild species of rye shows that all contain 75K -secalins, indicating that the duplication and divergence, if not the translocation, occurred before speciation of the genus.     

A map of rye chromosome 4R with cytological and isozyme markers

The progeny of two crosses between a structural heterozygote for a reciprocal translocation (4RL/5RL) and a homozygote for the standard chromosome arrangement and of four crosses between standard chromosome homozygotes were analysed in rye (Secale cereale L. cv Ailés) for the electrophoretic patterns of five different leaf and endosperm isozymes (LAP, PGM, NDH, ADH and EPER). The presence or absence of the quadrivalents at metaphase I (MI) was also tested. Loci Adh-1, Pgm-1 and Ndh-1 were located on chromosome arm 4RS, and locus Eper-1 on chromosome arm 4RL. Locus Lap-2 was located on the 4RS chromosome arm. The estimated distances among the different linked loci support the following gene order: Eper1¨ (breakpoint-centromere)¨Lap-2¨ ¨Adh-1 ¨Pgm-1¨Ndh-1. These results provide evidence for the chromosomal location of Lap-2 locus on chromosome arm 4RS in cv Ailés. A high negative interference was detected between the zones delimited by centromere and Lap-2, and Lap-2 and Pgm-1 in plants with the 4RL/5RL translocation.Abbreviations LAP leucine aminopeptidase - PGM phosphoglucomutase - NDH NADH dehydrogenase - ADH alchohol dehydrogenase - EPER endosperm peroxidase     

RFLP-based genetic map of the homoeologous group 3 chromosomes of wheat and rye

Summary Genetic maps of chromosomes 3A, 3B and 3D of wheat and 3R of rye were developed using 22 DNA probes and two isozyme marker systems. Analysis of the 49 loci mapped showed extreme clustering around the centromere in all four maps, with large gaps in the distal chromosome regions, which is interpreted as being due to strong localisation of recombination towards the ends of the wheat and rye chromosomes. In the centromeric regions gene orders are highly conserved between the three wheat genomes and the rye genome. However, the unpredictable behaviour of the DNA clones that map in distal chromosome locations may indicate that the genomes are diverging most rapidly in the regions of higher recombination. A comparison of cDNA and genomic probes showed the latter to be much more efficient for revealing RFLP. Some classes of gDNA clones, i.e. chromosome-specific sequences and those hybridizing in a non-homoeologous manner, were seen to be most polymorphic. Correlations between map locations and RFLP levels showed no clear relationship. In addition to anonymous DNA clones, the locations of known function clones, sedoheptulose-1,7-bisphosphatase (XSbp), carboxypeptidase I (XCxp1) and a bZIP protein (XEmbp), were ascertained along with those for two isozyme loci, Mal-1 and Est-5.     

Comparative salt tolerance in triticale,wheat and rye during germination

Summary Differences in salt tolerance of wheat and barley have been observed but knowledge of such differences in triticale (X Triticosecale Wittmack) cultivars is of potential importance. Effects of six salinity levels (0 to 2% NaCl) on germination of triticales Beagle and 6TA 131 in comparison to wheat and rye were determined at 15–20°C. Beagle triticale and rye showed similar trends in germination reduction as salinity increased from 0 to 1.5% NaCl and exhibited fairly high salt tolerance. However, 6TA 131 triticale and wheat showed a significant drop in germination even at 0.5% NaCl concentration and were more susceptible to salt injury.     

A self-fertile trigeneric hybrid,Triticum aestivum ×Agropyron michnoi ×Secale cereale

Trigeneric hybrids between the (Triticum aestivum ×Agropyron michnoi) F₁ (CM, 2n=5x=35; ABDPP) and two winter rye (Secale cereale L., 2n=2x=14; RR) cultivars, Wugong 774 and AR-132, were synthesized. Such trigeneric hybrids could be used to transfer resistance genes for powdery mildew from rye to CM and subsequently to common wheat and to identify (1) the effects of the P genome ofAgropyron on the self-fertility of the hybrids and (2) the differences in genetic background between rye cultivars with marked differences in pollinating habit. The trigeneric hybrids varied widely in morphology and showed a high level of resistance to such diseases as barley yellow dwarf virus (BYDV), stripe rust, leaf rust, stem rust, and powdery mildew. Selfed and many backcross derivatives were obtained from the trigeneric hybrids. The results indicated that rye cvs Wugong 774 and AR132 arose from different gene pools and that the P genome ofAgropyron carries gene(s) responsible for chromosome segregation, leading to functional gamete formation and self-fertility of the hybrids. The F₂ and BC₁ plants could be obtained in two ways — fusion of the unreduced gametes and the assumed apomixis of unreduced female gametes in the trigeneric hybrid plant II-4 — which indicates that this trigeneric hybrid may be a special genetic stock. Chromosome pairing in the trigeneric hybrids and ways of producing wheat/rye and wheat/Agropyron translocations are discussed.     

Amplification of repeated DNA sequences in wheat X rye hybrids regenerated from tissue culture

Summary Previous C-banding analysis of wheat (Triticum aestivum)X rye (Secale cereale) hybrids regenerated from tissue culture revealed enlarged C-bands in some rye chromosomes, but the molecular nature of the change was not determined. In situ hybridization using two DNA probes containing repeated sequences from rye telomeric heterochromatin was conducted on these wheatX rye hybrids and their progeny to investigate the occurrence of amplification in repeated sequences. Clones pSC 74 and pSC 119, which contain sequences from the 480-bp and 120-bp repeated DNA families of rye, respectively, were used as probes. Amplification of 480-bp repeated sequences in the short arm telomere of chromosome 7R was detected in three wheatxrye hybrids and their progeny. The amplified 480-bp sequences were detected by an enlarged hybridization site for pSC 74 at the 7RS telomere, and by the appearance at this same telomeric site of an unlabeled, blue chromosome segment in an otherwise completely brown chromosome hybridizing entirely to the biotin-labeled pSC 119 probe. This variant form of chromosome 7R was not observed in several Chaupon plants, or in the other hybrids derived from the same embryos, indicating the origin of the change in tissue culture. The amplified sequences were inherited up to at least three generations. Deletions and translocations were also observed.Contribution No. 87-9-J, Kansas Agricultural Experiment Station, Kansas State University     

Transfer of Hessian fly resistance from rye to wheat via radiation-induced terminal and intercalary chromosomal translocations

Summary A new Hessian fly (Mayetiola destructor) resistance gene derived from Balbo rye and its transfer to hexaploid wheat via radiation-induced terminal and intercalary chromosomal translocations are described. Crosses between resistant Balbo rye and susceptible Suwon 92 wheat and between the F₁ amphidiploids and susceptible TAM 106 and Amigo wheats produced resistant BC₂F₃ lines that were identified by C-banding analysis as being 6RL telocentric addition lines. Comparative chromosomal analyses and resistance tests revealed that the resistance gene is located on the 6RL telocentric chromosome. X-irradiated pollen of 6RL addition plants was used to fertilize plants of susceptible wheats TAM 106, TAM 101, and Vona. After several generations of selection for resistance, new sublines were obtained that were homogeneous for resistance. Thirteen of these lines were analyzed by C-banding, and three different wheat-6RL chromosomal translocations (T) were identified. Wheat chromosomes involved in the translocations were 6B, 4B, and 4A. Almost the complete 6RL arm is present in T6BS · 6BL-6RL. Only the distal half of 6RL is present in T4BS · 4BL-6RL, which locates the resistance gene in the distal half of 6RL. Only a very small segment (ca 1.0 m) of the distal region of 6RL is present in an intercalary translocation (Ti) Ti4AS · 4AL-6RL-4AL. The 6RL segment is inserted in the intercalary region between the centromere of chromosome 4A and the large proximal C-band of 4AL. The break-points of the translocations are outside the region of the centromere, indicating that they were induced by the X-ray treatment. All three translocations are cytologically stable and can be used directly in wheat breeding programs.Cooperative investigations of the Kansas Agricultural Experiment Station, Departments of Entomology and Plant Pathology, the Wheat Genetics Resource Center, Kansas State University, and the US Department of Agriculture, Agricultural Research Service. Contribution No. 91-117-JDeceased