Authors:Wojciech Sodkiewicz, Barbara Apolinarska, and Teresa Sodkiewicz
The aim of this work was to distinguish between chromosomes of A-genome of 6x-triticale and A
and to evaluate the efficiency of distinguishing secondary tetraploid triticale lines varying in A/A
chromosome substitutions. These secondary tetraploid lines were developed by crossing of this hexaploid triticales with the synthetic allotetraploid
T. monococcum/S. cereale
RR) as a male parent. The comparative C-banding showed that chromosomes of
are less easily stained than are chromosomes of hexaploid triticale. Precise differential staining of tetraploid triticale lines with complete A genome distinguished chromosomes originating from A
-genome of primary A
RR allotetraploid and those substituted from A-genome of 6x-triticale. Seventeen different chromosome constitutions of tetraploid triticale with complete A-genome were identified. The assessed substitutions showed close linkage with several phenotypic traits. Chromosomes 2A, 4A, 5A and 6A participated in substitutions with significantly higher frequency than other chromosomes of A-genome.
Authors:J. Díaz De León, R. Escoppinichi, N. Geraldo, A. Börner, and M. Röder
The parents (the landrace Chinese spring (CS) and a synthetic hexaploids (S6x)) and 17 derived single chromosome substitution lines (SL) were grown in parallel in the field under non-saline (1.0 dSm−1) and saline (12.0 dSm−1) conditions, and evaluated for a set of phenotypic traits. The performance of CS indicated it to have borderline salinity tolerance with respect to all of the traits except for leaf area (for which it behaved in as a salinity sensitive type). The SL 4D was early in booting, ear emergence, flowering and maturity, while 5D and 2B SLs were both late. The 2B SL produce 33% more ears than CS. The 5D SL under-performed with respect to ear weight, grain number per ear, grain weight per ear and 1000-grain weight both under non-saline and saline conditions. Under saline conditions, four SLs (1A>5A>1D>2B) outperformed Cs for ear length, and six SLs (1D>6A>4B>3A>3B>3D) showed an improved grain weight. The grains produce by the 2B SL were smaller than those of CS. Leaf area developed better in four SLs (4D>2B>1A>7D) than in CS.
Authors:T. Efremova, N. Trubacheeva, E. Chumanova, E. Badaeva, L. Rosseeva, V. Arbuzova, and L. Pershina
As a result of crossing substituted lines Saratovskaya 29 (S29) 5R(5A) and S29 5R(5D) with line L2075 (T1RS·1BL), two homozygous wheat-rye lines were obtained in the F7 generation and identified as T5AS·5RL + T1RS·1BL and 5R(5D) + T1RS·1BL, respectively. The rye chromosomes yare of different origins: 5R originated from spring rye Onohoskaya and 1RS from winter rye Saratovskaya 5. A new Robertsonian translocation was obtained where the 5RL arm was translocated to the short arm of wheat chromosome 5A, resulting in the T5AS·5RL translocation chromosome. Two translocations, T5AS·5RL and T1RS·1BL, and one chromosome substitution, 5R(5D), were identified and confirmed to be compensating on the basis of genomic in situ hybridisation, C-banding and 1RS- and 5R-specific PCR markers. Evaluation of resistance to fungal diseases revealed that homozygous T5AS·5RL + T1RS·1BL and 5R(5D) + T1RS·1BL lines are resistant to leaf rust and powdery mildew.
The association between genomic constitution and agronomic traits was studied in F2 plants and F3:4 families of two crosses between a winter hexaploid triticale line with a 2D(2R) chromosome substitution and two hexaploid triticale cultivars carrying the complete rye genome (BBAARR). The analyses revealed that 2D(2R) substitution reduces plant height and spikelet number per spike, increases the 1,000-kernel weight, does not reduce grain shrivelling, and promotes early heading and anthesis. 2D(2R) substitution lines exhibit deeper postharvest seed dormancy, which provides resistance to preharvest sprouting. However, 2D(2R) substitution lines are not recommended for winter hexaploid triticale cultivar development purposes due to their reduced grain productivity.
Authors:A. Vágújfalvi, V. Nagy, A. Soltész, and G. Galiba
Testing cereal frost tolerance goes back for decades in the Agricultural Research Institute, Martonvásár, Hungary. The climatic programmes used in the plant growth chamber have proved to be fairly efficient, but these methods are time-consuming and have become quite expensive in recent years. An attempt was made to shorten this process by reducing the cold hardening phase, and the freezing test has been simplified and shortened by measuring the relative conductance of leaf segments frozen in a liquid freezer. Frost-tolerant and sensitive wheat lines were tested, and the sensitivity of the system was checked by testing single chromosome substitution lines. Differences were found for all lines frozen at different temperatures. To reduce the costs of the experiment it was attempted to cold-harden the plants not only in a growth chamber but also in a cold room under very low light intensity and it was found that even under thess unfavourable conditions the plants developed a certain level of frost tolerance. The simplified frost tolerance test has proved to be effective, but requires further improvement due to the unsatisfactory significance levels.
Authors:R. Batra, P. Kumar, M.R. Jangra, N. Passricha, and V.K. Sikka
Adenosine diphosphate glucose pyrophosphorylase (AGPase) is the rate limiting enzyme of starch biosynthesis that directly affects the wheat productivity. AGPase and grain growth rate (GGR) discerned to be following strict temperature regimen in wheat disomic chromosome substitution (DCS) lines. The first half of grain filling period had chromosome 1B and 2D as prominent players, whereas second half was mainly controlled by chromosomes 6A and 5B. Chromosome 2D had major contribution towards yield in a specific temperature range of 23 ± 1.5 °C during initial stages of grain filling which can serve as an effective early screening tool for terminal heat tolerance in wheat. Chromosome 2D with highest amylose content can also be utilized to produce low digestibility flour. Grain yield was found to be significantly associated with spikes/plant, grains/spike, grain weight/spike and plant biomass. Further, path analysis indicated that though grains/spike had less direct effect on grain yield but its indirect impact on grain yield via AGPase-21 activity was high.
Authors:A. Rojas, T. Castellanos, and J. Díaz De León
Wheat improves some traits when inoculated with Azospirillum. However, inconsistent results have been observed in field experiments. The ability of Azospirillum brasilense Cd to adhere to wheat was tested in a germplasm panel consisting of a number of bread wheat cultivars, synthetic hexaploids, synthetic derivatives, and a partial set of single chromosome substitution lines to determine the plant genetic role. Seeds of genotypes were grown in modified Hoagland's medium at seedling stage and then roots were inoculated with the bacteria and adhered cells were counted. The majority of the bread wheat cultivars and synthetic derivatives and some of the synthetic hexaploids were able to support bacterial adhesion. Neither the age of the seedling nor the imposition of either salinity stress or nitrogen starvation had any effect on the extent of adhesion. A pedigree analysis revealed that the root-adhered A. brasilense cultivars shared common ancestor(s), and the substitution line analysis suggested that the genes underlying the trait were located on chromosomes 5D and 6D. The present results are consistent with the notion that the D genome is the source of genetic variation for the capacity of A. brasilense to adhere to the seedling roots.