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.
Wild diploid goatgrass, Aegilops tauschii Coss., is the D-genome donor to hexaploid bread wheat. Goatgrass has been crossed with tetraploid durum wheat (Triticum turgidum var. durum L.) and hexaploid bread wheat (T. aestivum L. ssp. aestivum) to broaden the genetic base of bread wheat. We examined the contribution of main stem water-soluble carbohydrates (WSC) and current assimilates to grain yield in one goatgrass relative to those in one durum and four cultivars of bread wheat under well-watered and droughted field conditions across two years. Drought reduced grain yield and its components. Number of tillers per plant was higher in goatgrass, but 55% of tillers produced were sterile. Number of grains per spike was lower in goatgrass. Grain weight was the component severely limiting potential yield in goatgrass. Main stem WSC and concentration was lowest in goatgrass. Linear rate of grain growth in goatgrass was 20 and 17 mg spike−1 day−1 under well-watered and droughted conditions, whereas those in durum and bread wheats ranged from 55 to 73 and from 37 to 60 mg spike−1day−1, respectively. Current assimilates were the major source of carbon to fill the grains under both irrigation regimes. A large number of goatgrass accessions and adapted durum cultivars should be examined for grain yield and its components to identify promising accessions to be used in producing synthetics.
Authors:Marianna Merakchiyska, Juliana Stoinova, Slavka Paunova, and Sonia Phileva
Investigations have been carried out on the resistance toward toxic amounts of Cu
in the medium of three tritordeum forms — the hexaploids: HT9 and HT31 and the octoploid HT73, containing genes of the wild perennial barley
. The length and weight of the roots as well as of the above-ground part of 10-day old plants, grown on solutions with CuSO
O at concentrations of 10
M and 10
M and those grown on water (control) were measured. Toxic Cu
concentrations in the medium resulted in an increase of the variation coefficient for the studied parameters which was more distinctly expressed in the hexaploid tritordeums. The octoploid tritordeum HT73 demonstrated greater tolerance to the heavy metal based on the changes in the weight and length of the above-ground parts of the plants. No significant changes in the pigment content and in the chlorophyll fluorescence parameters were established indicating that the photosynthetic apparatus activity was not substantially affected by toxic Cu
Authors:L. Tyryshkin, M. Gashimov, M. Kolesova, and N. Anphilova
Seedling (juvenile) resistance to 3 foliar diseases was studied in 540 samples of 24
L. species from VIR World Collection. Samples of
T. timopheevii, T. militinae, T. zhukovskyi, T. timococcum
and 4 of
were highly resistant to complex population of leaf rust causal agent. Presence of
clones virulent to samples of
(synthetic hexaploids with genome A
GD) indicates to partial suppression of resistance from species with A
G genome by D genome of
. Two samples of
and one of
were resistant to dark-brown leaf spot blotch. Three samples of
and two of
were classified as resistant after inoculation with mixture of 7
isolates. All 239 samples of 6 species studied were susceptible to common root rot. The causes of differences between our results and that obtained in other studies are discussed.
As regards wheat varieties constituting a natural ploid series the issue of analysing diploid, tetraploid and hexaploid species is tropical since ancient varieties can play significant roles in contemporary agriculture as well. Seventeen winter wheat varieties, out of which 2 diploid varieties carried genome A, 9 diploidic types had genomes AB, two varieties had genomes AG and four varieties were hexaploid ones with genomes ABD, were analysed from the point of view of their amino acid compositions. The amino acid contents of Asp, Thr, Ser, Glu, Gly, Ala, Cys, Val, Met, Ile, Leu, Tyr, Phe, His, Lys, Arg, Pro (a total of 17) were determined in the varieties listed above.It has been found that the amino acid contents of the grains genotype AA
exceeded the amino acid content of
in respect of all the amino acids analysed in this experiment, with Glu being the only exception. In comparison with the
wheat, essential amino acid contents showed a similarly favourable picture in the diploidic varieties mentioned. As regards type AB tetraploid varieties excesses of 13–16%, in comparison to the
wheat, were found in essential amino acid contents. The amounts of non-essential amino acids in all the winter wheat varieties showed decreases irrespective of the ploid level.What concerns the total amino acid content, all the winter wheat varieties with the exception of
(AB) contained less amino acid than the
wheat. All the monocarbonic acid and aromatic as well as heterocyclic amino acid contents of the wildly growing
(A) and the grown
(A) (with polaric, apolaric R groups, diamino radicles) exceeded the same contents of
. The value of the monoamino-dicarbonic acid, however, was lower in our experiment.
Authors:O. Tereshchenko, T. Pshenichnikova, E. Salina, and E. Khlestkina
Purple colour of wheat grain is determined by anthocyanin accumulation in the pericarp. This trait is controlled in hexaploid Triticum aestivum or tetraploid T. durum wheats by two complementary dominant genes Pp1 (chromosome 7B) and Pp3 (chromosome 2A). It remained unclear, whether functional alleles of one of the two complementary Pp genes occur in the diploid progenitors of allopolyploid wheat or in tetraploid T. timopheevii. In the current study, a purple-grained wheat line PC was obtained by crossing non-purple-grained T. aestivum Line 821 and Line 102/00i carrying introgressions from T. timopheevii and Aegilops speltoides, respectively. Crosses of lines 821 and 102/00i with a number of tester lines and cultivars did not result in purple-grained genotypes suggesting that expression of this trait in PC was controlled by complementary factors, one located in the T. timopheevii introgression and the other in the introgression inherited from Ae. speltoides. Genotyping of PC and other parental lines using microsatellite markers located on wheat chromosomes 7B and 2A showed that PC carries chromosome 7S of Ae. speltoides substituting for chromosome 7B, whereas chromosome 2A of PC contains an extended introgression from T. timopheevii.