A Cross between Bread Wheat and a 2D(2R) Disomic Substitution Triticale Line Leads to the Formation of a Novel Disomic Addition Line and Provides Information of the Role of Rye Secalins on Breadmaking Characteristics

A bread wheat line (N11) and a disomic 2D(2R) substitution triticale line were crossed and backrossed four times. At each step electrophoretic selection for the seeds that possessed, simultaneously, the complete set of high molecular weight glutenin subunits of N11 and the two high molecular weight secalins of rye, present in the 2D(2R) line, was carried out. Molecular cytogenetic analyses of the BC4F8 generation revealed that the selection carried out produced a disomic addition line (2n = 44). The pair of additional chromosomes consisted of the long arm of chromosome 1R (1RL) from rye fused with the satellite body of the wheat chromosome 6B. Rheological analyses revealed that the dough obtained by the new addition line had higher quality characteristics when compared with the two parents. The role of the two additional high molecular weight secalins, present in the disomic addition line, in influencing improved dough characteristics is discussed.

A Cross between Bread Wheat and a 2D(2R) Disomic Substitution Triticale Line Leads to the Formation of a Novel Disomic Addition Line and Provides Information of the Role of Rye Secalins on Breadmaking Characteristics

A bread wheat line (N11) and a disomic 2D(2R) substitution triticale line have been crossed and backrossed four times. At each step electrophoretic selection for the seeds that possessed, simultaneously, the complete set of high molecular weight glutenin subunits of N11 and the two high molecular weight secalins of rye, present in the 2D(2R) line, was carried out. Molecular cytogenetic analyses of the BC4F5 generation have revealed that the selection carried out had produced a disomic addition line (2n=44). The pair of additional chromosomes consisted of the long arm of chromosome 1R (1RL) from rye fused with the satellite body of the wheat chromosome 6B. Rheological analyses revealed that the dough obtained by the new addition line had higher quality characteristics when compared with the two parents. The role of the two additional high molecular weight secalins, present in the disomic addition line, in influencing improved dough characteristics is discussed.

Molecular Cytogenetic Analysis and Meiotic Pairing Behavior of Progenies Originating from a Hexaploid Triticale (×Triticosecale, Wittmack) and Bread Wheat (Triticum aestivum, L.) Cross

The chromosomal constitution of 9 dwarf (D) and 8 semidwarf (SD) lines derived by crossing hexaploid Triticale line NA-75 (AABBRR, 2n = 6x = 42) with Triticumaestivum (AABBDD, 2n = 6x = 42) cv. Chinese Spring was investigated using molecular cytogenetic techniques: fluorescence in situ hybridization and genomic in situ hybridization. A wheat-rye translocation (T4DS.7RL), 8 substitution lines, and a ditelosomic addition line (7RSdt) were identified. In the substitution lines, 1, 2, or 4 pairs of wheat chromosomes, belonging to the A, B, or D genome, were replaced by rye chromosomes. Substitutions between chromosomes belonging to different wheat genomes [5B(5A), 1D(1B)] also occurred. The lines were genetically stable, each carrying 42 chromosomes, except the wheat-rye ditelosomic addition line, which carried 21 pairs of wheat chromosomes and 1 pair of rye telocentric chromosomes (7RS). The chromosome pairing behavior of the lines was studied during metaphase I of meiosis. The chromosome pairing level and the number of ring bivalents were different for each line. Besides rod bivalents, univalent and multivalent associations (tri- and quadrivalents) were also detected. The main goal of the experiment was to develop genetically stable wheat/Triticale recombinant lines carrying chromosomes/chromatin fragments originating from the R genome of Triticale line NA-75. Introgression of rye genes into hexaploid wheat can broaden its genetic diversity, and the newly developed lines can be used in wheat breeding programs.

Breeding Progress and Performance of Wheat Cultivars in Different Environments in Israel from 1970 to 2002

The behaviour of wheat cultivars in environments with different yield level and the progress of wheat breeding in Israel were investigated by a statistical exploration of 353 Regional Wheat Trials, performed from 1970 to 2002. In the trials 125 experimental and commercial cultivars of Triticum aestivum, 11 of T. durum and one Triticale line (summarised as cultivars) were tested. The yield levels of trials ranged from 0.5 to 8.8 t/ha. The assumption of additive cultivar effects did not fit to trials differing much in yield since genetic variance within trials was closely related to the yield level of trials. The cultivars differed in grain yield by multiplicative factors that were well reproducible and highly correlated across environments. The best differentiation of cultivars, expressed as the ratio of genetic to residual variance, was found in high yielding environments. Specific adaptations of cultivars to the environmental yield level were absent or negligible and the ranking of the tested cultivars was very similar across environments. Residual variance was very low after standardisation to equal genetic variance. Statistical cultivar × environment interactions might be largely artefacts of additive yield models, applied to non-standardised data. Significant differences between cultivars were observed in relative yield, stability of relative yield, earliness, height, kernel size and hectoliter weight. Cultivar yield was significantly associated with lodging resistance, short straw and low protein content, while the association with other traits was low or non-significant. Breeding resulted in an increase of the average relative yield of cultivars in regional trials by more than 30%. The top recent bread wheat cultivar Galil is yielding approximately twice more than cv. Florence Aurore, the leading cultivar till the seventies. Breeding progress for yield was fast in the seventies, but only moderate in the last 10 years, with cv. Galil as the top yielder since 1996. Further breeding progress might be harder to achieve than in the past.  

A preliminary report on the identification of SSR markers for bunt (Tilletia sp.) resistance in wheat

Common bunt and dwarf bunt, caused by Tilletia caries (DC) Tul., T. foetida (Wallr) Liro., and T. controversa, respectively, can still cause yield and quality losses, despite the availability of effective chemical treatments. Growing resistant cultivars remains the best option for economical and environmental reasons, and is the only effective alternative in organic farming. As the durability of bunt resistance has proved to be rather poor, the pyramiding of resistance genes has been envisaged as a method of extending the life of resistance genes. Molecular markers can considerably increase the efficiency of gene pyramiding, but, because incomplete expression of both susceptibility and resistance genes makes accurate phenotyping difficult, very few markers associated with bunt resistance genes have been identified to date. This is why, at the National Agricultural Research & Development Institute Fundulea-Romania, along with the breeding program for bunt resistance, research on the possible use of molecular markers for Marker Assisted Selection (MAS) was developed. Random F₅or F₄lines from crosses between a Bt11 line or a bunt resistant line derived from a Triticale/2 × wheat, and susceptible parents, were phenotyped under artificial inoculation conditions, and were genotyped using primers for several markers. Preliminary results suggest that the Bt11 gene is located on chromosome 3B, and may be associated with marker loci Xbarc180, Xwmc623, Xwmc808 and Xgwm285. The gene for bunt resistance transferred from Triticale (line F00628G34-1 – possessing a 1A/1R translocation) can make MAS possible by using 1R specific markers. Although these results are preliminary, they already prove to be useful for the diversification and pyramiding of bunt resistance genes in breeding for durability of bunt resistance.

Isolation, mapping and application of a repetitive DNA sequence in wheat (Triticum aestivum) A and B genomes

Simple sequence repeat (SSR) analysis was performed on five Secale species, four Triticum species and a Triticale line Fenzhi-1 using 102 pairs of microsatellite primers. A 387-bp specific DNA fragment FZ387 (GenBank accession no. EF179137) was obtained from the Triticale Fenzhi-1 with primer Xgwm614, without amplification in Secale. NCBI BLAST revealed that this FZ387 sequence had 94% and 95% similarity to part of the Gypsy Ty3-LTR retrotransposon Fatima in Triticum monoccocum (AY485644) and Triticum turgidum (AY494981), respectively. A pair of specific polymerase chain reaction (PCR) primers, FaF and FaR, was designed based on the conserved region of this FZ387 sequence. The amplification of primer pair Xgwm614F and FaR revealed that a specific 350-bp band (designation as A350) was obtained from the species containing A chromosomes. Furthermore, PCR on Langdon Chinese Spring substitution lines was performed, and the results found that this segment was located on both long and short arms of all A chromosomes. However, the amplification of primer pair FaF and Xgwm614R gave rise to a specific DNA band of about 350 bp (designated AB350) from materials containing A and/or B chromosomes. The wild species of wheat and the relatives were amplified using the two pairs of primers, and revealed that only A350 and AB350 were found in Chinese Spring (CS). Sequence comparison and variation of SSR primers binding regions of FZ387 indicated that significant diversity might exist in the internal sequence of this Fatima-like element among triticeae genomes. Meanwhile, both A350 and AB350 can be used as molecular markers for the detection of A and AB genomes.

Molecular cytogenetic and agronomic characterization of advanced generations of wheat × triticale hybrids resistant to Diuraphis noxia (Mordvilko): application of GISH and microsatellite markers

The PI 386148 triticale from Russia is among the highest resistant line to the Russian wheat aphid (RWA) ( Diuraphis noxia (Mordvilko)). This triticale line was used as the male parent in crosses with Lamar wheat ( Triticum aestivum L.). The F1 plants were backcrossed to Lamar wheat. The progenies were tested for RWA biotype 1 reaction for at least eight backcross and selfing generations. Five lines from these selections were identified for their resistance to the RWA and their seeds were increased for agronomic and other characterizations. Molecular and cytological analyses of these lines were performed using genomic in situ hybridization and rye chromosome-specific microsatellites markers. Three lines were cytologically stable and carried a pair of rye ( Secale strictum (C. Presl) C. Presl) chromosomes as disomic addition lines of 1R. One line was unstable and showed a moderate level of mixoploidy with monosomic additions of 1R. Duplication of rye chromosome 1R was also identified. No wheat–rye chromosome interchange was detected, suggesting little homology between S. strictum and T. aestivum chromosomes. Specific microsatellite primers were used to identify the rye chromosomes present in each line. One rye chromosome, 1R, from the donor species contains genes for RWA resistance. Grain yield and test weight of three of the lines were similar to some adapted released wheat varieties under stress conditions.

C-banding in meiosis: an approach to the study of wheat and rye genome interactions in triticale

Meiosis in four primary hexaploid triticale lines, in their component two tetraploid wheat and two rye parents, and in the hybrids obtained by crossing within each ploidic level was studied using Giemsa banding. The individual chromosomes were identified and their meiotic behaviour at first metaphase was analyzed in each line. In each new triticale line, the level of pairing for wheat chromosomes was moderately reduced and for rye chromosomes was very significantly reduced, in comparison with that of the wheat and rye parents used to synthesize it. The pairing intensity observed suggests the presence of a strong negative intergenomic interaction between the rye and wheat genomes in triticale, irrespective of whether the rye is in a homozygous or heterozygous genotypic condition. The homozygosity or heterozygosity in the wheat constituent does not appear to effect the behaviour of the rye chromosomes in triticale.Key words: triticale, meiosis, C-banding, heterosis.

Mixtures of annual legumes and small-grained cereals for forage production under low rainfall

SUMMARYTwo small-grained cereals, Mulga oats and a triticale line, and two legumes, local vetch and local peas, were grown in pure stands and in mixtures at various cereal: legume seed ratios (20:80, 40:60, 60:40 and 80:20) for three successive cropping years, 1981/82 to 1983/84, at Laxia and Dromolaxia, Cyprus, in each year.The cereal pure stands produced, on average, more dry matter, 8·40 t/ha, and more digestible organic matter, 4·12 t/ha, than the legume pure stands, 3·68 and 2·18 t/ha, respectively. On average, total dry matter production decreased linearly as the seed proportion of the legume component in the mixture increased. The proportion of the legume in the harvested material was much lower than expected from the seed ratios. The highest proportion of legume was seen in the mixtures of peas with triticale and ranged from 8·1 to 35·5% at the various sowing rates. Digestibility and crude protein content were highest in the mixtures of triticale and peas.