Authors:L. Szunics, E. Pocsai, Lu. Szunics, and G. Vida
In recent years viral diseases have become more frequent on cereals in Hungary. In the breeding nursery of the Martonvásár Institute, which contains stocks with very diverse genetic backgrounds, wheat suffered major attacks by viruses in 1972, 1976, 1980, 1981, 1982, 1986, 1990, 1996 and 1998. The winter barley plots incurred great damage in 1989 and 1990, while a large proportion of the durum wheat was destroyed in 1996. In 1982 barley yellow dwarf virus caused an epidemic in Fejér County and on many farms the damage was so great that the fields had to be ploughed up. The following nine viruses, which impose a threat to cereals, have been identified in Hungary to date: 1966: barley yellow dwarf luteovirus (BYDV), 1984: barley stripe mosaic hordeivirus (BSMV), 1985: wheat streak mosaic tritimovirus (WSMV), 1986: brome mosaic bromovirus (BMV), cocksfoot mottle sobemovirus (CfMV), 1988: wheat dwarf mastrevirus (WDV), 1989: barley yellow mosaic bymovirus (BYMV), 1990: agropyron mosaic rymovirus (AgMV) and ryegrass mosaic rymovirus (RyMV). The most frequent and widespread of these are BYDV and WDV, which are thus able to cause the greatest quantitative and qualitative damage. On the basis of six years’ data (1994–2000), neither BYDV nor WDV could be isolated from 35.7% of 1163 samples exhibiting leaf yellowing and dwarfness. This indicates that other viruses pathogenic to cereals can induce similar symptoms. Among the plants showing symptoms of virus infection, 47.3% were attacked by WDV alone, in proportions ranging from 28.8% in barley to 69.7% in triticale. The degree of infection changed from year to year: WDV was isolated from 0.0% of symptom-exhibiting plants in 1999, from 48.5% in 1997 and from 94.0% in 2000. Barley yellow dwarf virus was only isolated alone from 9.5% of the samples, while it was isolated together with wheat dwarf virus from 7.5% of the samples. Considerable differences were observed between the cereal species: only 5.6% of the durum wheat samples were infected with BYDV, while this figure was 28.1% for oats. There was also a significant year effect. In 1996 triticale was not infected, while in 2000 5.0% of the plants exhibited symptoms and in 1994 45.5% of the plants were hosts to the BYD virus. Under Hungarian conditions all five known serotypes can be found, though in different proportions depending on the cereal species and the year. The most frequent is RPV (27.4%), followed by PAV (26.9%), SGV (15.6%), MAV (15.3%) and RMV (14.8%). In samples collected from oats only the PAV serotype was found. The MAV serotype has never been isolated from triticale. The dominant serotype was RPV (60.7%) in wheat samples, SGV (36.0%) in durum wheat and RMV (29.1%) in barley.
, J. C., Feillet, P. (1987): Genetic and technological basis of protein quality for durumwheat in pasta. pp. 59–71. In: Pattakon, V. (ed.),
Proc. EEC Symp. on Protein Evaluation in Cereals and Legumes
. Cereal Institute, Thessaloniki, Greece
The low seedling vigour of Russian wildrye grass (
) (RWR) limits its use. Shading from durum wheat (
) reduced RWR leaf number, tiller number, leaf area and seedling dry weight in a growth room experiment. Treatments with similar shading differed in tiller number and dry weight, which suggested that light quality may have also contributed to these responses. In a second growth room experiment, light intensity (PAR) and red:far-red light ratio (670:730 nm) were altered by coloured plastic filters suspended above seedlings of Russian wildrye, crested wheatgrass (
) (CWG) and Dahurian wildrye grass (
) (DWR). Leaf area, tiller number and dry weight of RWR seedlings were reduced by declining red:far-red light ratio while light intensity differences at similar red:far-red ratio did not affect these variables. CWG exhibited similar responses to declining red:far-red light ratio as RWR, except that it exhibited a seedling weight response to light intensity. DWR tiller number was not responsive to low red:far-red light ratio but rather to low light intensity. However, DWR seedling weight, tiller weight and leaf area were responsive to declining red:far-red light ratio. These results indicate that RWR seedlings are sensitive to light quality changes caused by neighbouring plants.
This study examines the occurrence of aflatoxins (AFS) and ochratoxin A (OTA) in bread and durum wheat samples. A total of 141 samples were collected from eleven different regions of Turkey. An analytical method based on liquid extraction, immunoaffinity column (IAC) clean-up followed by high performance liquid chromatography (HPLC) was used for the determination of AFs and OTA levels. As a result, AFs and OTA were detected in 2% and 9.2% of wheat samples at concentrations varying from 0.21 to 0.44 µg kg−1 and from 0.1 to 3.2 µg kg−1, respectively. Aflatoxin B1 (AFB1) and aflatoxin B2 (AFB2) were found positive in samples ranging between 0.21–0.35 µg kg−1 and 0.094 µg kg−1, respectively. However, none of the samples contained aflatoxin G1 (AFG1) and aflatoxin G2 (AFG2). The study also recommended that contamination levels in wheat and wheat-based products should be routinely monitored in greater sample numbers to insure food safety.
Authors:G. Mangini, D. Nigro, B. Margiotta, P. De Vita, A. Gadaleta, R. Simeone, and A. Blanco
During the last century wheat landraces were replaced by modern wheat cultivars leading to a gradual process of genetic erosion. Landraces genotyping and phenotyping are strategically useful, as they could broaden the genetic base of modern cultivars. In this research, we explored Single Nucleotide Polymorphism (SNP) markers diversity in a collection of common and durum wheats, including both landraces and Italian elite cultivars. A panel of 6,872 SNP markers was used to analyze the genetic variability among the accessions, using both the Principal Components Analysis (PCA) and the Neighbour Joining clustering method. PCA analysis separated common wheat accessions from durum ones, and allowed to group separately durum landraces from durum elite cultivars. The Neighbour joining clustering validated PCA results, and moreover, separated common wheat landraces from common elite cultivars. The clustering results demonstrated that Italian durum landraces were poorly exploited in modern breeding programs. Combining cluster results with heterozygosity levels observed, it was possible to clarify synonymy and homonymy cases identified for Bianchetta, Risciola, Saragolla, Timilia and Dauno III accessions. The SNP panel was also used to detect the minimum number of markers to discriminate the studied accessions. A set of 33 SNPs were found to be highly informative and used for a molecular barcode, which could be useful for cultivar identification and for the traceability of wheat end-products.
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:E. Bakhshandeh, A. Soltani, E. Zeinali, and M. Kallate-Arabi
Crop simulation models use allometric relationships to predict plant height from vegetative characteristics. The objective of this study was to find relationships between plant height (PH) and number of leaves on main stem (NLMS), stem dry weight (SDW) (g plant−1) and total vegetative components (leaves and stems) dry weight (TVDW) (g plant−1) in wheat (Triticum aestivum L.). For this purpose, an experiment was conducted using seven wheat cultivars including two durum wheat cultivars (Arya and Taro) and five bread wheat cultivars (Darya, Kuhdasht, Shiroudi, Tajan and Zagros) under irrigated and rainfed conditions during 2008-2009 at Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran. The experimental design was a randomized complete block design with four replications. Sampling was started from beginning of tillering and continued until maturity. A segmented nonlinear regression model was used to describe allometric relationships between PH and the vegetative characteristics. The results showed that there was no significant difference between cultivars and the two conditions for allometric relationships, so one equation was usable for all cultivars under both irrigated and rainfed conditions. Significant relationships were found between PH and NLMS (R2 = 0.94), SDW (R2 = 0.95) and TVDW (R2 = 0.95). These equations can be used for estimation of PH in simulation models of wheat.
Stone mulch offers potential benefits for water conservation in many rain-fed agricultural systems of the arid regions. The effects of stone mulch on transpiration and grain yield were examined for a durum wheat crop grown under soil water deficit stress. In a greenhouse trial, stone mulches with two levels of ground coverage significantly decreased soil-surface evaporation and increased crop transpiration. The transpiration increase contributed to increases both in biomass and grain yield. Field experiments over two cropping seasons confirmed yield increases of 12% in soil half-covered and 24% in soil fully-covered by stones. These significant yield increases indicate the potential usefulness of stone mulch technology in rain-fed cereal cropping. It is suggested that stones should not be removed from cereal fields unless their presence obstructs management severely. It remains to develop technologies for effectively managing soils containing large numbers of sizable stones in order to obtain the benefits of the potential yield increase associated with their presence on the soil surface.
Recently, four novel genes named Pinb-2, with 57–60% sequence similarity with wild-type allele Pinb-D1a coding for grain-hardness related puroindoline B have been shown to occur on homoeologous group 7 chromosomes in bread wheat (Triticum aestivum). In the present report, T. monococcum ssp. monococcum (Am genome) revealed a Pinb-2 gene with a poly-G tract and an in-frame TAG stop codon at the 5′ terminus of the coding DNA sequence. The stop codon was observed in 53 accessions of different geographic origins, suggesting that Pinb-2 in ‘monococcum’ wheat is unlikely to be expressed. By contrast, the coding DNA sequence of Pinb-2 in T. urartu (Au genome) was found to be 99% identical to its counterpart on chromosome 7AL in bread and durum (T. turgidum ssp. durum) wheat. Moreover, a sequence very similar to “urartu” Pinb-2 was found in tetraploid wheat T. timopheevii and hexaploid wheat T. zhukovskyi. This latter species exhibited an additional Pinb-2 pseudogene inherited from T. monococcum. The results are discussed in relation to the lineage of T. zhukovskyi and the potential role of Pin-b2 on kernel texture.