Cytological identification of 1B/1R wheat-rye translocations in winter wheat breeding lines

Summary The incorporation of rye (S. cereale L.) chromatin into winter wheat (T. aestivum L.) cultivars is often achieved via hybridization of unadapted wheat-rye translocation lines with adapted wheat germplasm. Identification of progenies possessing the translocated chromosome has traditionally involved phenotypic screening for the desired rye characteristics. In this study, the Giemsa N-banding technique was evaluated as a potential screening tool for detection of 1B/1R wheat-rye translocations. Five breeding lines were examined from the pedigree Aurora/2^*TAM W-101. The differential banding patterns of chromosome 1B contributed by TAM W-101 and chromosome 1B/1R contributed by Aurora allowed unequivocal identification of translocation genotypes. Three of the lines were found to be heterogeneous, whereby plants were homozygous for either the normal 1B or the translocated 1B/1R chromosome. The remaining two lines were observed to be homozygous and homogeneous for the translocated 1B/1R chromosome. The implication of N-banding chromosomal analyses to wheat breeding is presented.Contribution No. J-5172, Department of Agronomy, Oklahoma Agriculture Experiment Station, Oklahoma State University, Stillwater, OK74078.     

Ecotypic variation of water-soluble carbohydrate concentration and winter hardiness in cocksfoot (Dactylis glomerata L.)

The variation of the water-soluble carbohydrate (WSC) concentration in foliage and stubble and winter hardiness among cocksfoot (Dactylis glomerata L.) ecotypes originated from diverse countries were studied in the field in order to find a breeding material for the improvement of WSC. The total WSC concentration of foliage was found to be highest in Japanese cultivars and lowest in ecotypes from northern Europe in summer and autumn. The variation of fructan concentration in stubble among ecotypes was larger than the variation of mono and disaccharide concentrations in stubble and that of total WSC concentration in foliage in both winters over which this study was conducted. The total WSC and fructan concentrations in the stubble of ecotypes from Spain and southern Europe, derived from the Mediterranean region, were highest in summer. Ecotypes from Japan showed the highest concentration of total WSC in stubble, and were especially high in fructan concentration in autumn. Ecotypes from France, central Europe and central Asia, like Japanese cultivars, also showed a high fructan concentration. The latitude of origin was negatively correlated with WSC concentration and plant vigor in autumn. The altitude of origin was negatively correlated with plant vigor in autumn and positively correlated with fructan concentration in stubble, winter hardiness and snow endurance. Typhula snow blight resistance was related with the amount of the increase in fructan in the plants and with their growth habits in autumn. The fructan concentration of foliage and stubble in autumn was found to be closely related with winter hardiness in cocksfoot ecotypes. A breeding material which has a high WSC concentration in the foliage could not be found among the ecotypes in this study. However, some ecotypes that showed disease resistance, good winter hardiness and plant vigor would be useful as breeding materials for Hokkaido.     

Heterotic effects of wheat-rye chromosomal translocations on agronomic traits of hybrid wheat (Triticum aestivum L.) under an adequate moisture regime

Translocated chromosomes T1BL⋅1RS and T1AL⋅1RS have been widely used in many wheat (Triticum aestivum L.) breeding programs to develop high yielding cultivars. The objective of this study was to evaluate the heterotic effects of T1BL⋅1RS + T1AL⋅1RS, T1BL⋅1RS, and T1AL⋅1RS on yield and yield components of hybrid wheat grown under adequate moisture regimes. Thirteen hybrid wheats and seven parents with different chromosome constitutions relative to T1AL⋅1RS and T1BL⋅1RS were evaluated in a randomized complete block design. Variable performance was observed among the hybrids tested. Two of the three hybrids with T1BL⋅1RS + T1AL⋅1RS, produced 25.26% and 44.64% more grain than the hybrids with only T1BL⋅1RS. This was due to increased biomass, harvest index (HI) and spike density. However, the combination of these two translocations resulted in reduced kernels/spike, spikelets/spike and spike length compared to the T1BL⋅1R Stranslocation alone. When comparing closely related parents, the parent with T1AL⋅1RS produced 23.51% more grain yield than the non-translocated parent. The presence of T1AL⋅1RS resulted in 10.37% heterotic advantage for yield due to increased biomass, KW, and spike density. When the two wheat-rye translocated chromosomes are present in the same hybrid, T1AL⋅1RS seems to have a positive effect on yield through spike density and HI, but masks the effects of T1BL⋅1RS for some agronomic traits. This revised version was published online in August 2006 with corrections to the Cover Date.     

Kernel hardness and baking quality of wheat — A genetic analysis using chromosome substitution lines

Summary An attempt was made to identify the chromosomal location of genetic control of a few components of wheat quality, using chromosome substitution lines of Cappelle Desprez, Cheyenne, Hope, and Timstein into the recipient variety Chinese Spring.Major factors for kernel hardness and increased baking absorption were found on chromosomes 5D of Cheyenne and Hope, and on 3B, 5D and 7D of Timstein. In Timstein, the presence of one of these chromosomes sufficed to make the wheat kernels hard.Factors for favourable dough properties were identified on a few other chromosomes, different in various varieties. These were 1A of Cappelle Desprez and Cheyenne, 3B of Hope, and 2D of Timstein. All but one of these chromosomes showed an increase in loaf volume to a level in-between those of the recipient variety Chinese Spring and the donor varieties. No relationship was found between kernel hardness and dough-making and baking properties.It was assumed that wheat quality is due to a combination of kernel hardness and favourable dough-making properties. As the genes for these factors are located on different chromosomes, it should not be too difficult to introduce both factors in existing varieties with poor baking properties. In a wheat breeding programme, the quality of new lines can be assessed in a rather simple way by determining kernel hardness and dough stability.     

The relationships of hardening period and the expression of frost resistance in chromosome substitution lines of wheat

Summary The highly frost resistant wheat variety Cheyenne (donor) and the poorly frost resistant variety Chinese Spring (recipient) were frozen at –9° C and –11° C at various stages of hardening, as were a number of substitution lines of these two varieties (CS/Ch 3A, CS/Ch 5A, CS/Ch 7A, CS/Ch 2B, CS/Ch 4B, CS/Ch 5B, CS/Ch 4D, CS/Ch 5D). Chromosomes 5A, 5B, 5D, 4B and 7A of Cheyenne increased the frost resistance of the recipient variety to varying extents. However, the frost resistance changed not only as a function of the different chromosomes, but also as a function of the duration of hardening, indicating that genes responsible for frost resistance are expressed differently during different phases of the hardening process.     

Effect of common bunt on the frost resistance and winter hardiness of wheat (Triticum aestivum L.) lines containing Bt genes

In order to determine the effects of bunt inoculation on frost resistance and winter hardiness in lines containing resistance genes, the bunt [Tilletia foetida (Wallroth) Liro, T. caries (DC.) Tulasne] susceptibility of wheat lines containing bunt resistance genesBt1 to Bt10 and the effect of the year on the degree of infection were studied over six years from 1991 to 1997 in an artificial inoculation nursery. Uninoculated and artificially inoculated wheat plants were tested for frost resistance in the phytotron in 1995 and in the field in boxes in three years from 1994/95 to 1996/97. The line withBt10 was very resistant, lines with Bt5, Bt6, Bt8 and Bt9 were resistant, the line with Bt4 was moderately resistant, those with Bt2 and Bt3 were moderately susceptible, the line with Bt1 was susceptible and the line with Bt7 was very susceptible to the local bunt population in Hungary. Bunt incidence also varied over years. The frost resistance of the Bt lines was generally lower after bunt inoculation than that of uninoculated plants. The increased frost kill in inoculated plants was not correlated with the extent of varietal susceptibility to bunt. Some lines with resistance, namely those with Bt5 (1.6% infection), Bt8 (0.6%) and Bt10 (0.0%), suffered significantly greater frost kill in the young plant stage as the result of bunt inoculation. By contrast, the Bt7line had excellent frost resistance and winter hardiness but suffered the greatest extent of bunt infection, whereas the Bt6 line had good frost resistance and good bunt resistance. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effects of homoeologous group 1 and 6 chromosomes of the Cappelle-Desprez (Bezostaya 1) substitution lines on aspects of bread-making quality of wheat

Summary The group 1 and 6 inter-varietal chromosome substitution lines of Cappelle-Desprez (Bezostaya 1) were intercrossed along with the donor and recipient varieties, Cappelle-Desprez and Bezostaya 1, to give 36 genetically different families. The analysis of the means of these families showed that variation in SDS-sedimentation volume fitted a predominantly additive model. There were no significant within or between chromosome interactions among the group 1 and 6 chromosomes. Nor was there any evidence for interactions between these chromosomes and those of the background. Significant dominance/within chromosome interactions amongst the background chromosomes were however detected. Some of the positive effects on SDS-sedimentation were associated with increased grain hardness. Chromosome effects on % grain protein were not correlated with SDS-sedimentation.     

Genetic analysis of hexaploid wheat,Triticum aestivum using intervarietal chromosome substitution lines—protein content and grain weight

Summary The 21 intervarietal chromosome substitution lines of the cultivar Hope in Chinese Spring were used to analyse the genetic differences between the two cultivars Hope and Chinese Spring in grain protein content and grain weight.Only one chromosome of Hope, 5D, significantly influenced grain protein content of Chinese Spring. Its influence was of only minor effect and was to decrease protein content expression of Chinese Spring. It has been postulated that the genetic control of protein content, in this instance, is most likely due to many genes each of small effect.Five chromosomes of Hope influenced the 1000 grain weight value of normal Chinese Spring, all increasing its expression. Chromosomes 1A, 4A and 5B were of major effect and 3A and 6A of comparatively minor effect. A minimal estimate of five genes determines the difference in grain size between these cultivars. The possible evolutionary significance of the contribution of the A genome of bread wheat to grain size determination is discussed. On the basis of certain findings of this study, proposals are made for breeding for increased grain size in hexaploid wheat.     

The effect of chromosome 1AL/1RS translocation on agronomic performance of 85 F2-derived F6 lines from three Triticum aestivum L. crosses

Summary The effect of the 1AL/1RS chromosome translocation on grain yield and other agronomic characteristics of 85 random F₂-derived F₆ bulks from three 1AL 1RS × 1A bread wheat crosses was determined under optimum and reduced irrigation conditions at CIANO, Yaqui Valley, Sonora, Mexico, during the 1991–1992 and 1992–1993 crop production cycles. Harvest plots of 5.0 m² were arranged in an alpha lattice design with three replications. The 1AL/1RS translocation increased grain yield, above-ground biomass, spikes/m², and test weight under both irrigated and dryland conditions. Homozygous chromosome 1A lines, on the other hand, possessed longer spikes with more grains. The 1AL/1RS cultivars had an advantage in 1000-grain weight, which was detected only under optimum irrigation. The translocation lines showed later maturity and longer grainfilling period than the 1A genotypes under one irrigation treatment. A significant relationship between grain yield and test weight was detected only among the 1AL/1RS genotypes, indicating that they possess heavier and plumper grains than the 1A genotypes. These results encourage the continued use of the 1AL/1RS translocation in wheat improvement.     

Control and inheritance of resistance to yellow rust in Triticum aestivum-Lophopyrum elongatum chromosome substitution lines

A set of T. aestivum-L. elongatum chromosome substitution lines was tested for yellow rust resistance at the seedling stage. Inheritance of the resistance and esterase-5 (Est-5) variation were studied. The results demonstrated that L.elongatum carried a new gene(s) conferring yellow rust resistance. This gene was dominant and located on chromosome 3E of L. elongatum. The biochemical locus encoding Est-5was also located on chromosome 3E, and co-segregated with theYr gene(s) in the wheat background. The transmission frequencies of chromosome 3E in 3E(3A) × CS, 3E(3B) × CS and 3E(3D) × CS hybrids were scored.None of the hybrids transmitted the alien chromosome at thetheoretical maximum rate, but the transmission frequencies ofchromosome 3E in F₂ populations of 3E(3A) × CS and 3E(3D) × CS were significantly higher than in thatof 3E(3B) × CS.     

A comparison of yield and yield component selection in winter wheat

Summary Three populations of winter wheat were formed by crossing Avrora to Sage, TAM W-101, and Danne. Approximately 10% of the F₂ plants from these crosses were selected for high and low levels of number of tillers per plant, number of kernels per spike, 1000-kernel weight, and grain yield. Forty-eight solid seeded F₃ lines obtained from the selected F₂ plants were then selected for high and low expressions of yield components and grain yield. Realized heritabilities were estimated. Indirect responses of yield to yield component selection and direct response to selection for grain yield were measured. Heritabilities were low for tiller number, number of kernels per spike and kernel weights but were high or intermediate for grain yield when selection occurred in the F₂ generation. When selection was practiced in the F₃ generation, heritabilities for tiller number and yield were low, but were intermediate to high for number of kernels per spike and kernel weight and high heritabilities were found for kernel weight. Selection for kernel weight often increased grain yield; however, direct selection for grain yields was usually as effective.Journal article no. J-4488 of the Oklahoma Agri. Exp. Stn., Stillwater, Oklahoma 74074.     

Nitrogen and phosphorus uptake and utilization efficiency in D(R) substitution lines of hexaploid triticale

Two sets of disomic substitution lines, derived from the cultivars ‘Presto’ and ‘Rhino’ of triticale, with rye chromosome pairs replaced by their wheat D‐genome homoeologues, were tested in hydroponic culture for nitrogen and phosphorus uptake and utilization efficiency. The effect of a substitution on the amount of absorbed nutrients was predominantly negative and proportional to the effect on plant dry matter. Significant decreases were found for the substitutions 5D(5R), 6D(6R) of both cultivars, 2D(2R), 4D(4R) of ‘Presto’ and 3D(3R) of ‘Rhino’. On the other hand, the nitrogen utilization efficiency was significantly increased in all substitution lines, with the exception of the 1D(1R) ones. The differences in phosphorus utilization were generally positive, but less pronounced, and significant only in the lines 2D(2R) and 6D(6R). The data suggest that presence of both rye and D‐genome chromosomes is conducive for the best effect of the applied N and P fertilizers.     

A gene for hybrid necrosis in an inbred line of rye (Secale cereale L.)

Summary An inbred line of rye (Secale cereale L.) has been found to carry a gene for hybrid necrosis. This gene was detected in crosses with a highly crossable wheat (Triticum aestivum L.) genotype which carries the gene Ne₂. This appears to be the first report of a gene for hybrid necrosis being present in the rye genome.     

Location of a gene for frost resistance on chromosome 5A of wheat

Summary A gene for frost resistance on chromosome 5A of wheat was located using single chromosome recombinant lines from the cross between the substitution line Hobbit (Triticum spelta 5A) and Hobbit. In this sample of recombinant lines the locus for frost resistance, designated Fr1, is completely linked to the locus Vrn1 controlling vernalisation requirement. The results can be explained by a pleiotropic action of the Vrn1 locus or close genetic linkage between Vrn1 and Fr1. Further detailed study is necessary to resolve these alternative hypotheses.     

Reciprocal monosomic analysis of frost resistance on chromosome 5A in wheat

Summary F₂ monosomic analysis and the direct comparisons between aneuploid series from different varieties of wheat suggest the likelihood of allelic variation. It is impossible however, from these studies to prove unequivocally that allelic variation exists. Some effects can be due to chromosome dosage rather than allelic variation. This disadvantage was overcome by using reciprocal monosomic analysis to study the genetic control of frost resistance on chromosome 5A in wheat. Data support the previous results obtained by F₂ monosomic and substitution analysis. The chromosome 5A has been shown to be the one which carries the major allelic differences that distinguish wheat varieties Chinese Spring, Rannyaya 12 and Mironovskaya 808 for frost resistance.     

Genetic analysis of inbred lines and their crosses for resistance to head blight (Fusarium culmorum,F. graminearum) in winter rye

Summary For genetic analysis of head blight in winter rye (Secale cereale) caused by Fusarium culmorum, six homozygous inbred lines from the Petkus gene pool were crossed in all combinations to obtain 15 diallel F₁ crosses and the corresponding 15 F₂ crosses. These materials and 10 additional inbreds were artificially inoculated in a 2-year field experiment. The inbreds were also tested with F. graminearum in a separate sub-experiment.Single disease rating, average disease rating, and yield components (grain-weight per spike, 1000-grain weight, kernel number per spike) relative to the non-inoculated treatment were significantly affected by Fusarium head blight in all material groups. The relative grain weight per spike ranged from 26% to 88%. Significant genotypic and genotype x year interaction variances were found throughout. Heritabilities were highest for homogeneous inbreds (h²=0.6–0.8) and lowest for heterogeneous F₂ crosses (h²=0.4–0.6). Disease rating and relative grain-weight per spike were highly correlated for the inbreds and F₂ crosses (r0.7, P0.01), but lower for the F₁ crosses (r0.6, P0.05). Inter-annual correlation coefficients for disease ratings and relative grain-weight per spike ranged from r0.7 (inbreds) to r0.5 (F₂ crosses). The diallel analysis showed significant GCA effects only for relative 1000-grain weight in 1990, but significant SCA and SCAx year interaction variances for most traits. The resistances of 16 inbreds to F. culmorum and F. graminearum were tightly associated for all traits (r=0.96–0.97, P0.01).In conclusion, only slow progress can be expected from selecting for Fusarium head blight resistance in rye due to the limited amount of additive genetic variance and the great improtance of environmental factors.     

The site of action of crossability genes (Kr 1, Kr 2) between Triticum and Secale. II. Proportion of pistils containing pollen tubes and effects of alternate pollination on seed set

Summary Different wheat genotypes (T. aestivum) were crossed with rye to ascertain the site or sites of manifestation of the crossability genes, Kr ₁ and Kr ₂. By using fluorescence microscopy, it was found that the order of increasing proportion of wheat micropyles containing pollen tubes is strongly correlated with the levels of crossability with rye. High crossable genotypes have more micropyles containing pollen tubes than those of the low crossable ones. Most of the inhibition or retardation of pollen tubes occurred between the style base and top of the embryo sac, expecially with the low crossable genotypes where both Kr-genes are present. The results also indicate that Kr ₁ is a greater inhibitor than Kr ₂. Seed set is also highly correlated with the number or proportion of micropyles having pollen tubes. Alternate pollinations seem to support the view that rye pollen tubes do not reach the micropyles of the low crossable genotypes, and hence when repollinated with wheat selfed seeds are produced.     

Association between partial resistance to S-(2-aminoethyl)L-cysteine and increased methionine levels in inbred lines of rye

Summary 223 highly inbred lines of winter rye were investigated, using the in vitro culture of mature embryos, for their resistance to lysine structural analogue S-(2-aminoethyl)L-cysteine (AEC). The AEC concentration 0.20 mM was comparable to that in other cereals.Embryos from ca. 3% of lines developed into plantlets with normal or reduced shoots and were classified as either resistant (r) or partly resistant (pr). The (r) and (pr) traits were recessive, nonallelic and most probably without maternal effect-as suggested by F₁ analysis.The (r) and (pr) lines had not changed the lysine content but surprisingly elevated methionine content. The possible factors which brought about such effect are discussed. Testing of (pr) lines for ethionine resistance showed partial resistance of one of them.     

Expression of 17 rye (Secale cereale L.) traits in a range of durum wheat (Triticum durum Desf.) and bread wheat (T. aestivum L.) genetic backgrounds

Summary Expression of 17 rye traits in 24 bread wheat x rye and 8 durum wheat x rye crosses was studied, using a self-compatible, homozygous, dwarf rye. Rye showed epistasis for hairiness on the peduncle in all the crosses of Triticum aestivum and T. durum wheats with rye. Dark greenness of leaves of rye was expressed in all the durum wheat x rye and in some of the bread wheat x rye crosses. Similarly, absence of auricle pubescence, a rye trait, was expressed in most of the durum wheat x rye crosses but not in the bread wheat x rye crosses, indicating the presence of inhibitors for these traits frequently on the D genome and rarely on the A and/or B genome of wheat. Most of the wide hybrids resembled rye fully or partially for intense waxy bloom on the leaf-sheath and for the absence of basal underdeveloped spikelets. Similarly, most of the amphihaploids resembled rye for the anthocyanin in the coleoptile, stem and node. The presence of some inhibitors on A and/or B genome of wheat was indicated in some of the wheat genotypes for the expression of rye traits viz. intense waxy bloom, anthocyanin in node and absence of basal underdeveloped spikelets. Enhancement in the level of expression of the intensity and length of bristles on the mid-rib of the glume of the hybrids might be due to wheat-rye interaction. Less number of florets/spikelet as in rye showed variable expression in different wheat backgrounds. Some other rye traits like absence of auricles, terminal spikelet and glume-awn were not expressed in the wheat background. The expression of some of the rye genes might have been influenced by their interaction with Triticum cytoplasm and/or the environment.     

Parental effects on crossability,embryo differentiation and plantlet recovery in wheat x rye hybrids

Summary One hexaploid wheat cultivar (Triticum aestivem) and two tetraploid wheat lines (T. durum) were crossed with seventeen inbred lines of rye (Secale cereale). Seed set, degree of hybrid embryo differentiation at the time of excision for in vitro culture and recovery of amphihaploid plantlets from various embryo categories were studied. Degree of embryo differentiation was predominantly determined by maternal wheats, paternal rye genotypes appearing to be of minor importance. T. aestivum x rye hybrid embryos were superior to those produced from T. durum for degree of differentiation. The proportion of plantlets developing from differentiated embryos was high for all wheat parents, whereas undifferentiated embryos were mostly unsuitable for plantlet production. The results revealed that cross-incompatibility in hexaploid wheat x rye crosses was due to failure of fertilization, while in tetraploid wheat x rye crosses it was caused by lack of embryo differentiation. Correlation analyses showed that seed set provided a criterion to predict the amphihaploid plantlets to be expected from a particular wheat x rye combination.