Crossability of tetraploid and hexaploid wheats with ryes for primary triticale production

Summary Crossability of wheat and rye was investigated during thirteen crop cycles in two contrasting locations to 1) evaluate tetraploid and hexaploid wheat parents in crosses with rye, 2) identify genotypes with high crossability and 3) assess the impact of environment on seed development. The majority of the tetraploid wheats crossed with rye had seed set around 20%, but very low embryo viability. Several wheat genotypes with seed set above 50% were identified. The hexaploid wheats crossed with rye showed poor seed set, but plant recovery was relatively high. The majority of the hexaploid wheats with highest seed set (20–30%) were from China. The results suggest differences in crossability between the rye populations, and wheat species by rye interactions. The crossability of the tetraploid and hexaploid wheats was affected by climate in the two locations.     

Spontaneous wheat/rye translocations from female meiotic products of hybrids between octoploid triticale and wheat

Summary Heptaploid hybrids between octoploid triticale and wheat were backcrossed as female parents with wheat to examine the rye chromosome distribution in the resultant progenies using genomic in situ hybridization (GISH). One hundred and one backcross (BC) seeds were examined and whole rye chromosome additions and substitutions, wheat/rye centric and noncentric translocations and rye telocentric chromosomes were detected. Dicentric wheat/rye translocated chromosomes were also observed. Comparisons were made with previous results on the rye chromosome distribution from male gametes of the same cross and differences were found, where in the female derived population a deficit of plants with more than two rye chromosomes was apparent relative to the anther derived population.     

Crossability percentages of some 1400 bread wheat varieties and lines with rye

Summary Two lists are provided: List 1 contains the percentages of crossability with rye of some 1400 varieties and lines of bread wheat; List 2 contains varieties having a high crossability with rye. It is believed that the publication of these data will be helpful to those wishing to cross bread varieties with rye and other species.     

Genetic control of esterase-6 isozymes in hexaploid wheat and rye

Summary The EST-6 leaf esterase phenotypes from euploid, nullisomic-tetrasomic and rye chromosome addition and substitution lines of common wheat were determined using polyacrylamide gel electrophoresis. Evidence is presented to demonstrate that Est-6 is a new set of genes, that are expressed in the leaf. The Est-6 gene set were clearly distinguished from the Est-5 genes which are expressed in the grain. The three homoeoallelic loci, Est-A6, Est-B6 and Est-D6, were located on chromosomes 3A, 3B and 3D. An Est-R6 gene was located on chromosome 6R is involved in rye. Some considerations concerning homoeology between homoeologous group 3 of wheat and the rye chromosome 6R are made.     

The crossability percentages of 96 bread wheat landraces and cultivars from Japan with rye

Summary Crossability of bread wheat (Triticum aestivum L.) from Japan with rye (Secale cereale L.) was investigated by controlled pollination. No normal seeds were produced, but numbers of shrivelled and small seeds with embryos were used to estimate crossability amongst the 96 accessions, viz: 0–10% (29), 10–30% (23), 30–50% (11), 50–90% (33). The investigation for the pedigrees of varieties with more than 50% crossability percentages showed that the kr alleles of some accessions derived from common ancestors.     

Crossability of some bread wheat landraces and improved cultivars from western Himalayas with rye

Summary Crossability of 62 bread wheat accessions (14 landraces from Himachal Pradesh and 48 others) was examined with rye. The 3 rye cultivars did not differ in their relative crossability with 4 of the wheat accessions studied. On the other hand, the wheat cultivars differed greatly among themselves in their crossability with rye. Most of the wheat cultivars showed poor (<10%) crossability. Two of the 14 landraces from Himachal Pradesh were found to be free from the crossability inhibitors as they showed very high (>50%) crossability, whereas none of the other 48 cultivars studied was so.     

Plant regeneration from immature inflorescence callus cultures of wheat,rye and triticale

Summary Callus cultures were initiated from inflorescence explants of wheat, rye and triticale on MS medium supplemented with 2 mgl^-1 2,4-D+5% CW or 2 mgl^-1 2,4-D+0.5 mgl^-1 BA. On transfer of the cultures to medium supplemented with 15% CW+0.2 mgl^-1 NAA or 1 mgl^-1 BA+0.1 mgl^-1 IAA, shoot buds and embryoids were produced. Full fledged plantlets obtained on MS medium supplemented with NAA were transferred to the field. Cytological analysis showed the plants to be diploid. However, the regenerated plantlets were shorter, produced fewer tillers and had lower fertility compared to the control.Abbreviations BA Benzyladenine - CW coconut water - IAA indoleacetic acid - NAA -naphthaleneacetic acid - 2,4-D 2,4-dichlorophenoxyacetic acid     

Crossability percentages of bread wheat collections from Tibet,China with rye

Summary The crossability percentages of 282 accessions of wheat (Triticum aestivum L.) collected in Tibet, China with rye (Secale cereale L.) have been tested. Five collections have a similar to and 277 accessions have a lower crossability percentage than Chinese Spring or are non-crossable with rye. The accessions with high crossability percentage occur along the highway near Lhasa. No landraces with higher crossability than Chinese Spring and rare landraces with similar crossability to Chinese Spring indicated that the landraces in Tibet region are different from those in Sichuan, Shaanxi and Henan provinces in the distribution frequency of high crossability, and there is no distribution of recessive kr4 alleles.     

Crossability percentages of bread wheat landraces from Shaanxi and Henan provinces,China with rye

Summary The crossability percentages of 118 landraces of wheat (Triticum aestivum L.) from Shaanxi and Henan provinces, China with rye (Secale cereale L.) have been tested. 14 landraces possess a higher crossability percentage than Chinese Spring, 30 landraces have a similar to and 74 landraces have a lower crossability percentage than Chinese Spring or are non-crossable with rye. Most landraces with high crossability percentage occur in south part of Shaanxi, and the west and southwest of Henan, their geographical distribution in these regions fits up with that in the Sichuan province.     

Crossability percentages of bread wheat landraces from Sichuan Province,China with rye

Summary The crossabilities of 177 landraces of wheat (Triticum aestivum L.) from Sichuan Basin and its adjacent mountain ranges with rye (Secale cereale L.) have been tested. 16 landraces possess a higher crossability than Chinese Spring, 34 landraces have a similar and 127 landraces have a lower crossability than Chinese Spring or are non-crossable with rye. Most landraces with high crossability occur in Qinling Mountain and Dabashan Mountain Ranges in north of Sichuan and the valleys of Minjiang River, Fujiang River and Jialinjiang River in Sichuan Basin.     

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.     

Doubled haploid production in winter wheat and triticale genotypes,using the Hordeum bulbosum system

Summary An attempt was made to produce doubled haploids on 16 winter wheat and six spring and winter triticale genotypes thought to carry genes for interspecific incompatibility. The potential for haploid production was maximized by the use of Hordeum bulbosum genotypes selected for high crossability on crossable wheat genotypes, the use of two post-pollination applications of gibberellic acid and by the pollination of immature florets.A low frequency of seed was set on both the wheat and the triticale genotypes, having mean seed sets of 0.20 per cent and 0.27 per cent respectively. Although the frequency of embryos (seed quality) was high, doubled haploid production was further limited by poor embryo differentiation and regeneration. Haploid plantlets were obtained from the wheat cultivars Moulin and Renard, although successful chromosome doubling and doubled haploid production was achieved in Moulin only.     

Reaction of triticale,wheat and rye accessions to graminaceous Fusarium spp. infection at the seedling and adult plant growth stages

Summary Pathogenicity of 20 isolates of 12 Fusarium species recovered from triticale seed against seedlings of 14 varieties of winter cereals (triticale, wheat, and rye) was tested. The most pathogenic inoculum was a mixture of isolates (a composite isolate) of all the species. The following species were individually the most pathogenic: F. avenaceum, F. culmorum, F. sambucinum var. coeruleum, and F. graminearum. Winter triticale was more resistant to seedling blight than rye but more susceptible than wheat.Also reactions of 31 winter and 12 spring varieties of cereals to head inoculation with a composite isolate of 4 Fusarium spp. (F. avenaceum, F. culmorum, F. graminearum, and F. sambucinum var. coeruleum) was studied. In comparison to other cereals of similar type winter and spring wheat appeared to be the most susceptible while winter rye reaction was comparable to winter triticale. Spring and winter triticale varieties responded to head infection intermediately.There was no significant correlation between seedling and head reactions to infection with Fusarium spp. for winter rye and triticale. For winter wheat a negative trend was found. The above findings imply that screening of cereals at the seedling stage can not be used to predict the resistance to head blight. Nevertheless, resistance at the stage is highly desirable to prevent excessive damage of the crops due to the seedling blight incited by Fusarium spp..     

Structure of the isozymes of the AAT-2 and AAT-3 systems of asparate aminotransferase in wheat,rye and triticale

Summary The electrophoretic isozyme phenotypes for the AAT-2 and AAT-3 regions of leaves of Triticum turgidum, T. aestivum, Secale cereale, x Triticosecale (hexaploid) and T. aestivum/ S. cereale 6R addition line are described. The phenotypes varied in distribution and relative intensity of the isozyme bands, which were densitometrically measured. The results are consistent with a hypothesis of the dimeric structure for the AAT-2 and AAT-3 systems.     

The derivation of compensating translocations involving homoeologous group 3 chromosomes of wheat and rye

Summary The Sr27 translocation in WRT238 was found to consist of chromosome arms 3RS of rye and 3AS of common wheat. An attempt was made to purposely produce compensating translocations having 3RS and a wheat homoeologous group 3L arm. To achieve this, plants, double monosomic for 3R and a wheat homoeologous group 3 chromosome, were irradiated (7.5 Gy gamma rays) or left untreated before being used to pollinate stem rust susceptible testers. Segregation for stem rust resistance was studied to identify F₂ families with Sr27-carrying translocated chromosomes, these were confirmed by means of C-banding. Compensating translocations 3RS3AL and 3RS3BL) were obtained readily and at similar frequencies from untreated and irradiated plants (respectively, 7.2% and 9.3%). Both translocation types have impaired transmission and segregate approximately 3: 2 (present: absent) in the F₂.     

Hybridization barriers between wheat and rye: In vitro pollen assays and electrophoretic survey

Summary Five- to seven-day-old ovaries from Triticum aestivum vars Hope (non-crossable), Chinese Spring (CS, crossable) and the chromosomal substitution line Chinese Spring/Hope 5B (CS/H5B) were used to test the hypothesis that an ovarian substance inhibits rye (Secale cereale var Wrens) pollen tube growth. In vitro assays on a semi-solid medium demonstrated that a soluble, dialyzed lysate from Hope or CS/H5B ovaries inhibited rye pollen tube elongation significantly more than a similar lysate from CS ovaries (26%, 13% and 5% respectively compared to controls). When only the 20 longest tubes from each sample were included in the analysis the relationship was maintained (33%, 22% and 15% for Hope, CS/H5B and CS respectively). Heating the Hope lysate at 100° C for 10 min reduced the inhibition from 26% to 14% for all pollen tubes measured (n = 51 per sample) and from 33% to 20% when only the 20 longest pollen tubes per sample were analyzed. Isoelectric focusing followed by sodium dodecyl sulfate polyacrylamide electrophoresis (IEF/SDS-PAGE) and non-equilibrium pH gradient electrophoresis (NEPHGE) revealed several differences in the polypeptide profiles of soluble lysates from vars Hope, CS and CS/H5B. While two striking differences were observed, a 50 kilodalton (kD) polypeptide with an isoelectric point (pI) of approximately 8.5 and 100 kD polypeptide (pI4) from CS lysates which were considerably reduced in lysates of Hope and CS/H5B, none were obviously associated with the Hope 5B chromosome and therefore cross-incompatibility.Mention of a trademark or proprietary product is for identification only and does not imply a guarantee or warranty of the product by the U.S. Department of Agriculture.     

Histological studies on the infection of triticale,wheat and rye byPuccinia recondita f.sp.tritici andP. recondita f.sp.recondita

Summary The reaction of eight triticales and of the respective wheat and rye parental lines to infection by the leaf rust fungi of wheat and rye were studied in the seedling stage. The histological observations indicated that wheat and triticale showed a typical nonhost reaction to the leaf rust of rye: sporelings of this fungus were arrested after the formation of primary infection hyphae and before the formation of extensively branched mycelium, mostly without necrosis of plant cells. The rye inbred lines were all susceptible to the rye leaf rust. The reaction of wheat and triticales to the wheat leaf rust was susceptible or resistant. The reaction of resistant lines could be early or late and complete or incomplete, but was associated with substantial necrosis of plant cells, and therefore entirely different from the nonhost reaction to rye leaf rust. In their reaction to wheat leaf rust the rye lines were similar to the resistant wheat and triticale lines. They did not show an important degree of nonhypersensitive early abortion as would be expected in a nonhost species. It appeared that genes for hypersensitive resistance in triticale may be contributed by either the wheat or the rye parental line.A screening of sixty wheat, rye and triticale lines confirmed the nonhost status of wheat and triticale to rye leaf rust and the hypersensitive or moderately susceptible reaction of rye to wheat leaf rust.     

Selection in tetraploid rye. III. Frequency and performance of aneuploids

Summary Aneuploidy was studied in populations selected for high seed-set with regular meiosis and low-seedset with irregular meiosis and an unselected population of the same origin. The frequency of aneuploids was significantly reduced in the high population that was characterised by increased bivalent frequency. In spite of a similar quadrivalent frequency in euploid plants of the low and the unselected population, the former population had a significantly higher frequency of aneuploids. However, there was no significant difference in the performance of aneuploid plants from the three populations. The results indicated that hyperaneuploid gametes were less functional than hypoaneuploid gametes but no significant difference was found in the performance of hypo- and hyperancuploids.     

The effect of interplot competition on yield assessment in triticale trials

Summary A series of experiments was carried out to investigate the effects of interplot competition on grain yield among hexaploid triticale cultivars of widely differing heights grown in 1.5 m wide plots. Three experiments in 1982 tested four triticale cultivars, ranging in final height from 63 to 104 cm, with four wheat standards, 62 to 82 cm in height, using a design balanced for nearest neighbours. Two further experiments in 1983 with the same design included eight triticale cultivars ranging in final height from 92 to 183 cm. In four of the five experiments, plot yields of both wheat and triticale were decreased by between one and two grammes per square metre for every centimetre by which the plot was exceeded by the mean height of its two neighbours. Plots which were taller than their neighbours showed a similar increase in yield. Such systematic biases in cultivar means are not reduced by randomisation and increased replication. Hence, in breeding trials, every effort should be made to group genotypes according to their final height so that competition effects between plots are reduced. For the final evaluation of varieties differing widely in height, where an estimate of error is required for variety comparisons and varietal differences are likely to be small, guard plots should be grown on either side of each experimental plot or harvesting should be restricted to the centre of larger plots.     

The crossing of common wheat (Triticum aestivum L.) with cultivated rye (Secale cereale L.). I. crossability,pollen grain germination and pollen tube growth

Summary The crossing of common wheat (Triticum aestivum L.) with rye (Secale cereale L.), and especially the action of the crossability genes of wheat, was studied using the readily crossable wheat cv Chinese Spring (genotype kr ₁ kr ₁ kr ₂ kr ₂ >), the poorly crossable wheat cv Hope (genotype Kr ₁ Kr ₁ Kr ₂ Kr ₂ ), as well as the disomic substitution line of chromosome 5B of Hope into Chinese Spring (CS/Hope 5B, genotype Kr ₁ Kr ₁ kr ₂ kr ₂ ). By comparing crossability and actual fertilization, the poor crossability with rye of both cv Hope and the CS/Hope 5B substitution line was shown to result from absence of fertilization. Studies of pollen grain germination and pollen tube growth showed that the dominant alleles of the crossability genes manifested themselves through retardation and eventually inhibition of pollen tube growth at the style base and in the ovary wall. In Hope the growth of all pollen tubes was inhibited, whereas in CS/Hope 5B rarely fertilization was achieved. The recessive alleles of the crossability genes do not seem to have an influence on the growth of rye pollen tubes in wheat pistils.