Preferential C-banding of wheat or rye chromosomes

Summary Using different stains, wheat chromosomes could be distinguished from rye chromosomes by preferential staining. C-bands of rye chromosomes were preferentially stained with Giemsa while those of wheat chromosomes were preferentially stained with either Leishman or Wright stain. Preferential staining aids the identification of wheat and rye chromosomes and chromosome segments and in particular the recognition of wheat/rye chromosome substitutions and translocations.     

C-banding pattern and meiotic pairing in five rye chromosomes of hexaploid triticale

Summary The meiotic behaviour of rye chromosomes 1R, 2R, 3R, 6R and 7R/4R of hexaploid triticale Cachirulo is analyzed using the C-banding technique. These chromosomes show different C-banding patterns and present different pairing levels at metaphase I. A decreasing effect of large telomeric heterochromatin bands on pairing is deduced from the following two main facts: i) The chromosome 7R/4R shows the highest pairing associated with the smallest amount of heterochromatin, ii) pairing levels of 2 R short arm and 3 R long arm which carry large telomeric bands are less than their respective long and short arms lacking telomeric heterochromatin. Possible desynaptic effects of heterochromatin are discussed although an asynaptic effect cannot be rejected.     

Identification of C-banded chromosomes in meiosis of common wheat,Triticum aestivum L.

Summary The C-banding pattern of nine meiotic chromosomes of common wheat (Triticum aestivum L.) as described. In F₁s of crosses between monosomics of Chinese Spring and two Spanish wheat cultivars, univalent chromosomes were used to aid the recognition and analysis of the C-banding pattern for the individual chromosomes. The identification of one chromosome involved in one translocation in Chinese Spring x Pané 247 has been made through heterochromatin bands observed in the chromosomes involved in multivalents.     

Cytogenetic analysis of forms produced by crossing hexaploid triticale with common wheat

Summary Hexaploid triticales were crossed with common wheats, and the resultant froms were selected for either triticale (AD 213/5-80) or common wheat (lines 381/80, 391/80, 393/80). The cytogenetic analysis showed that all forms differ in their chromosome composition. Triticale AD 213/5-80 and wheat line 381/80 were stable forms with 2n = 6x = 42. Lines 391/80 and 393/80 were cytologically unstable. In triticale AD 213/5-80, a 2R (2D) chromosome substitution was found. Each of the three wheat lines had a chromosome formed by the translocation of the short arm of IR into the long arm of the IB chromosome. In line 381/80, this chromosome seems to be inherited from the Kavkaz wheat variety. In lines 391/80 and 393/80, this chromosome apparently formed de novo since the parent forms did not have it. The karyotype of line 381/80 was found to contain rye chromosomes 4R/7R, 5R and 7R/4R. About 15% of the cells in line 391/80 contained an isochromosome for the 5R short arm and also a chromosome which arose from the translocation of the long arms of the 5D and 5R chromosomes. About one-third of the cells in the common wheat line 393/80 contained the 5R chromosome. This chromosome was normal or rearranged. Practical applications of the C-banding technique in the breeding of triticale is discussed.     

Comparative performance of bread wheat and hexaploid triticale cytoplasms

Summary Thirteen wheat-like advanced-generation triticale x wheat derivatives, having tetraploid wheat cytoplasm from triticale, were reciprocally crossed with three improved bread wheats, and the resulting F₁s were evaluated for determining the comparative performance of the bread wheat and triticale cytoplasms for different traits. Significant reciprocal differences in the mean performance were observed for days to heading, days to maturity, spikes/plant, flag-leaf area, peduncle length, plant height, spike length, grains/spike, 1,000-grain weight, grain yield and grain protein content, and most of them were in favour of hexaploid wheat cytoplasm. However, this superiority of the hexaploid cytoplasm was not universal for a particular trait, implying that the differences in the performance of the evaluated reciprocal crosses depended not solely on the cytoplasmic background, but also on the interplay of the specific genotype with the cytoplasm.     

Cytogenetic investigations in rye,wheat and triticale

Summary Chromosomes of tetra- and hexaploid wheat have been individually characterized by Giemsa and/or Leishman C-banding techniques. Appropriate methodological modifications resulted in almost identical staining of chromosomes of tetraploid wheat with Giemsa and Leishman solutions. Additionally comparison of Giemsa banded chromosomes of the A- and B-genome of Triticum turgidum 34 and Triticum aestivum cv Jubilar reveals similar or corresponding patterns in all homologous chromosomes with the exception of chromosome 7B. Apart from this intervarietal variation in certain homologous chromosomes of both wheat cultivars, intravarietal polymorphism is verified.     

Rye chromosome translocations in hexaploid wheat: a re-evaluation of the loss of heterochromatin from rye chromosomes

Summary Using in situ hybridization techniques, we have been able to identify the translocated chromosomes resulting from whole arm interchanges between homoeologous chromosomes of wheat and rye. This was possible because radioactive probes are available which recognize specific sites of highly repeated sequence DNA in either rye or wheat chromosomes. The translocated chromosomes analysed in detail were found in plants from a breeding programme designed to substitute chromosome 2R of rye into commercial wheat cultivars. The distribution of rye highly repeated DNA sequences showed modified chromosomes in which (a) most of the telomeric heterochromatin of the short arm and (b) all of the telomeric heterochromatin of the long arm, had disappeared. Subsequent analyses of these chromosomes assaying for wheat highly repeated DNA sequences showed that in type (a), the entire short arm of 2R had been replaced by the short arm of wheat chromosome 2B and in (b), the long arm of 2R had been replaced by the long arm of 2B. The use of these probes has also allowed us to show that rye heterochromatin has little effect on the pairing of the translocated wheat arm to its wheat homologue during meiosis. We have also characterized the chromosomes resulting from a 1B-1R translocation event.From these results, we suggest that the observed loss of telomeric heterochromatin from rye chromosomes in wheat is commonly due to wheat-rye chromosome translocations.     

Chromosomal alterations in the karyotype of triticale in comparison with the parental forms

Summary Wheat chromosomes of the primary winter hexaploid and octoploid triticales and of the parental durum and common wheat varieties were studied using morphometric analysis. The size of some heterochromatic segments was shown to change in triticale. Telomeric and intercalary C-bands both increased and decreased in size whereas centromeric bands only increased. The size variability of C-bands in triticale B-genome chromosomes decreased in most of the cases and increased only for several specific C-bands. The C-bands of homologous B-genome chromosomes changed in the same direction in both triticale forms. The changes in size of the C-bands found in R-genome chromosomes detected earlier in these triticale forms (Badaeva et al. 1986) were shown to coincide in their pattern with the size changes of C-bands in homeological B-genome chromosomes. Our data are indicative of regular, directed chromosomal changes in the triticale karyotype.     

The meiotic pairing of nine wheat chromosomes

Summary The meiotic identification of nine pairs of chromosomes at metaphase I of meiosis of Triticum aestivum (B genome, 4A and 7A) has been achieved using a Giemsa C-banding technique. As a result, the analysis of the pairing of each chromosome arm in disomic and monosomic intervarietal hybrids between Chinese Spring and the Spanish cultivar Pané 247 could be carried out. Differences in the chiasmata frequencies per chromosome arm cannot be explained on the basis of relative arm lengths only. Possible effects of arm-to-arm heterochromatic differences on meiotic pairing are discussed.     

Chromosome alterations in the karyotype of triticale in comparison with the parental forms

Summary R genome chromosomes were studied in two forms of primary triticales (hexaploid TPG-1/1-78 and octoploid AD 825) and in their parent rye forms (Secale cereale L. cv. Kharkovskaya 60 and VSKhI, respectively) using the methods of C-banding and morphometric analysis. The size of some heterochromatic segments was shown to alter in the karyotype of triticale. An increase in size was detected approximately in half of all telomeric C-bands; the size of the other C-bands either decreased or did not change. The frequencies of these alterations were 11. The variability in the size of telomeric C-bands in rye chromosomes diminished in both triticales studied. The two triticale forms inherited variants of R genome chromosome polymorphism predominantly with the medium size range of telomeric C-bands. The centromeric C-bands in both triticale forms either enlarged or did not alter. Possible mechanisms responsible for the observed pattern of alterations are discussed.     

Pairing and recombination between individual chromosomes of wheat and rye in hybrids carrying the ph1b mutation

Wheat-rye chromosome associations at metaphase I studied by Naranjo and Fernández-Rueda (1991) in ph1b ABDR hybrids have been reanalysed to establish the frequency of pairing between individual chromosomes of wheat and rye. Wheat chromosomes, except for 2A and 2D, and their arms were identified by C-banding. Diagnostic C-bands and other cytological markers such as telocentrics or translocations were used to identify each one of the rye chromosomes and their arms. Both the amount of telomeric C-heterochromatin and the structure of the rye chromosomes relative to wheat affected the level of wheatrye pairing. The degree to which rye chromosomes paired with their wheat homoeologues varied with each of the three wheat genomes; in most groups, the B-R association was more frequent than the A-R or D-R associations. Recombination between arms 1RL and 2RL and their homoeologues of wheat possessing a different telomeric C-banding pattern was detected and quantified at anaphase I. The frequency of recombinant chromosomes obtained supports the premise that recombination between wheat and rye chromosomes may be estimated from wheat-rye pairing.     

八倍体小黑麦×普通小麦杂种后代群体中的染色体易位

用改良的Giemsa C-带技术以单株为基础分析了八倍体小黑麦×普通小麦的杂种BC_1,F_(?)和F_(?)代植株的核型。在鉴定了C-带核型的1098株杂种后代植株中,发现了78条小麦-黑麦和277条黑麦-黑麦易位染色体。在不同的世代和株系中,小麦-黑麦染色体易位率变化在4.35—14.07%之间,平均7.10%;黑麦-黑麦染色体易位率在0.48—52.78%之间,平均25.23%。鉴定的小麦-黑麦易位染色体涉及了黑麦的14条不同的染色体臂和小麦的A、B和D组染色体。易位的48.57%发生在小麦和黑麦的部分同源染色体之间,51.43%发生在非部分同源染色体之间。不同的黑麦染色体臂参与易位的频率不同。小麦-黑麦染色体易位主要发生在杂种的早期世代,使用适当的选择技术在F_3获得了纯合的易位植株。文中讨论了快速选育易位系的技术和它们在小麦育种中的应用问题。     

Genetic interactions between wheat and rye genomes in triticale

Summary Six primary triticale lines were produced from two advanced breeding lines of Triticum durum and three inbred genotypes of Secale cereale. The wheat and rye parents and the triticale derivatives were crossed in all possible combinations within each species group. Chiasma and univalent frequency of parents and hybrids were determined. The primary triticale lines had more univalents and less chiasmata per pollen mother cell than the corresponding wheat and rye parents together. The parental wheat F₁ exhibited negative heterosis for chiasma frequency whereas all rye hybrids had much higher chiasma frequencies than their inbred parents. Triticale F₁s generally showed lower chiasma frequencies and more univalents than their parents, but the degree of pairing failure was dependent upon which of the parental species within the triticale, wheat or rye, was in the heterozygous state. F₁s with heterozygous wheat genome only showed the least reduction in chiasma number (presumably caused by gene actions within the wheat genome), while F₁s with heterozygous rye genome showed high reduction in chiasma frequency and an increase in pairing failure (induced by negative interactions between the heterozygous rye and the wheat genome in triticale). A high correlation was found between the frequency of undisturbed pollen mother cells and the frequency of aneuploids in the subsequent generation. A higher number of aneuploids occurred in those populations which were heterozygous for the rye genome.     

Two NAD-dependent alcohol dehydrogenases (E.C. 1.1.1.1) in callus cultures of wheat,rye and triticale

Summary Two NAD-dependent alcohol dehydrogenases ADH-1 and ADH-2, under independent genetic control of genes designated as Adh-1 and Adh-2 located on chromosomes 4A, 4B and 4D, have been reported in aestivum wheat (Hart 1980). Only ADH-1 is expressed in developing seeds, dry seeds, pollen and germinating seedlings. ADH-2 can be induced in seedling roots or shoots under conditions of partial anaerobiosis or by certain chemicals. Expression of ADH-1 and ADH-2 isoenzymes was investigated in undifferentiated calli from aestivum and durum wheats, rye, triticale and also in in vitro regenerated roots and leaves from aestivum cultures. Wheat callus cultures originating from seed, mature and immature embryos, mesocotyl and root, as well as cultures grown on media containing different supplements did not show any variation in the overall expression of ADH-1 or ADH-2, although differences in the band intensities were observed. The callus isoenzyme pattern was similar to that observed in roots under anaerobic conditions. Both ADH-1 and ADH-2 were expressed in in vitro regenerated roots but were absent in regenerated leaves. Expression of ADH-1 and ADH-2 in wheat calli seems to be related to the type of differentiation.     

Homoeologous relationships of Aegilops speltoides chromosomes to bread wheat

 Homoeologous pairing at metaphase I was analysed in the standard-type, ph2b and ph1b hybrids of Triticum aestivum (AABBDD) and Aegilops speltoides (SS). Data from relative pairing affinities were used to predict homoeologous relationships of Ae. speltoides chromosomes to wheat. Chromosomes of both species, and their arms, were identified by C-banding. The Ae. speltoides genotype carried genes that induced a high level of homoeologous pairing in the three types of hybrids analyzed. All arms of the seven chromosomes of the S genome showed normal homoeologous pairing, which implies that no apparent chromosome rearrangements occurred in the evolution of Ae. speltoides relative to wheat. A pattern of preferential pairing of two types, A-D and B-S, confirmed that the S genome is very closely related to the B genome of wheat. Although this pairing pattern was also reported in hybrids of wheat with Ae. longissima and Ae. sharonensis, a different behaviour was found in group 5 chromosomes. In the hybrids of Ae. speltoides, chromosome 5B-5S pairing was much more frequent than 5D-5S, while these chromosome associations reached similar frequencies in the hybrids of Ae. longissima and Ae. sharonensis. These results are in agreement with the hypothesis that the B genome of wheat is derived from Ae. speltoides. Received: 8 January 1998 / Accepted: 4 February 1998     

Plant regeneration and somaclonal variation from cultured immature embryos of sister lines of rye and triticale differing in their content of heterochromatin

Summary Plants were regenerated from cultured immature embryos of two pairs of sister lines of triticale (X Triticosecale) cvs Rosner and Drira and five sister lines of rye (Secale cereale). The triticale lines differ in heterochromatic content of a particular rye chromosome (6R or 7R), while the rye lines differ in only one heterochromatic band. Variation in morphogenetic response was present between the triticale cultivars and between the rye lines. One of the rye lines (7RL+ +) showed a distinctive superior response in terms of somatic embryogenesis. These findings are discussed in relation to factors affecting morphogenetic response and genetic stability in culture.     

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.     

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.     

Aluminium effects on growth and Al,Ca, Mg,K and P levels in triticale,wheat and rye

Summary The effects of A1 on the growth and mineral composition of different cultivars of triticale (X Triticosecale, Wittmack), wheat (Triticum aestivum L.) and rye (Secale cereale L.) growing in 1/5 strength Steinberg solutions containing 0 or 6 ppm A1 were evaluated after 32 days. Aluminum increased the concentrations of P and K in the roots and K in the tops of most of the cultivars tested. A1 tolerant triticale retained a lower concentration of Mg in the roots and tops than the A1 sensitive triticale, when subjected to A1 stress. In addition, A1 treatments resulted in smaller increases in root P for the A1 tolerant triticale than for the A1 sensitive cultivars.The concentration of root Ca and P of the A1 tolerant wheat cultivars were significantly below that of the more sensitive plants. Aluminum tolerance in rye appeared to be associated with lower Ca and higher Mg concentrations in the tops. The accumulation of P and A1 in the roots was characteristic of sensitivity in triticale, wheat and rye.