Zoltán Bedő

The HEALTHGRAIN Cereal Diversity Screen : Concept, Results, and Prospects

One hundred and fifty bread wheat lines and 50 other lines of small-grain cereals (spelt, durum wheat, Triticum monococcum, Triticum dicoccum, oats, rye, and barley) were selected for diversity in their geographical origin, age, and characteristics. They were grown on a single site in Hungary in 2004-2005, harvested, milled, and analyzed for a range of phytochemicals (tocols, sterols, phenolic acids, folates, alkylresorcinols) and fiber components that are considered to have health benefits. Detailed analyses of these components in the different species are reported in a series of accompanying papers. The present paper discusses the comparative levels of the bioactive components in the different species, showing differences in both ranges and mean amounts. Furthermore, detailed comparisons of the bread wheat lines show that it is possible to identify lines in which high levels of phytochemicals and dietary fiber components are combined with good yield and processing quality. This means that commercially competitive lines with high levels of bioactive components are a realistic goal for plant breeders.

Phytochemical and fiber components in oat varieties in the healthgrain diversity screen

The levels and compositions of a range of phytochemicals (sterols, tocols, avenanthramides, folates, phenolic acids) and dietary fiber components were determined in five oat cultivars (four husked and one naked) grown on a single site in 2005. The total levels of tocols, phenolic acids, and avenanthramides varied by over 2-fold between cultivars, but less variation occurred in total sterols and total folates. Limited variation was also observed in the dietary fiber content and composition of the four husked lines. These results indicate that it may be possible to selectively breed for lines with high contents of dietary fiber and specific groups of phytochemicals.

Transgenic approach to improve wheat (Triticum aestivum L.) nutritional quality

An amaranth (Amaranthus hypochondriacus) albumin gene, encoding the 35-kDa AmA1 protein of the seed, with a high content of essential amino acids, was used in the biolistic transformation of bread wheat (Triticum aestivum L.) variety Cadenza. The transformation cassette carried the ama1 gene under the control of a powerful wheat endosperm-specific promoter (1Bx17 HMW-GS). Southern-blot analysis of T1 lines confirmed the integration of the foreign gene, while RT-PCR and Western-blot analyses of the samples confirmed the transcription and translation of the transgene. The effects of the extra albumin protein on the properties of flour, produced from bulked T2 seeds, were calculated using total protein and essential amino acid content analysis, polymeric/monomeric protein and HMW/LMW glutenin subunit ratio measurements. The results indicated that not only can essential amino acid content be increased, but some parameters associated with functional quality may also be improved because of the expression of the AmA1 protein.

Effects of photo and thermo cycles on flowering time in barley: a genetical phenomics approach

The effects of synchronous photo (16 h daylength) and thermo (2 °C daily fluctuation) cycles on flowering time were compared with constant light and temperature treatments using two barley mapping populations derived from the facultative cultivar ‘Dicktoo’. The ‘Dicktoo’בMorex’ (spring) population (DM) segregates for functional differences in alleles of candidate genes for VRN-H1, VRN-H3, PPD-H1, and PPD-H2. The first two loci are associated with the vernalization response and the latter two with photoperiod sensitivity. The ‘Dicktoo’בKompolti korai’ (winter) population (DK) has a known functional polymorphism only at VRN-H2, a locus associated with vernalization sensitivity. Flowering time in both populations was accelerated when there was no fluctuating factor in the environment and was delayed to the greatest extent with the application of synchronous photo and thermo cycles. Alleles at VRN-H1, VRN-H2, PPD-H1, and PPD-H2—and their interactions—were found to be significant determinants of the increase/decrease in days to flower. Under synchronous photo and thermo cycles, plants with the Dicktoo (recessive) VRN-H1 allele flowered significantly later than those with the Kompolti korai (recessive) or Morex (dominant) VRN-H1 alleles. The Dicktoo VRN-H1 allele, together with the late-flowering allele at PPD-H1 and PPD-H2, led to the greatest delay. The application of synchronous photo and thermo cycles changed the epistatic interaction between VRN-H2 and VRN-H1: plants with Dicktoo type VRN-H1 flowered late, regardless of the allele phase at VRN-H2. Our results are novel in demonstrating the large effects of minor variations in environmental signals on flowering time: for example, a 2 °C thermo cycle caused a delay in flowering time of 70 d as compared to a constant temperature.

Diversity of agronomic and morphological traits in a mutant population of bread wheat studied in the Healthgrain program

A mutant population of spring wheat cv. Cadenza was produced at Rothamsted Research in 2004–5, both for TILLING and to generate variation in the contents of phytochemical components studied in the Healthgrain program. The agronomic and morphological properties of this mutant hexaploid wheat population (generations M3–M6) were studied in a 3-year field experiment. Most of the traits were scored according to UPOV TG/3/11, namely the time of ear emergence, plant height, ear glaucosity, shape, density and length, presence of awns and scurs, seasonal type, and grain colour. Other characters such as visible mutant phenotypes, ear sterility, heterogeneity of head rows, leaf colour and responses to powdery mildew and leaf rust were also studied. Variation in certain breadmaking quality parameters was also studied. The EMS mutant Cadenza lines studied showed wide diversity in terms of morphological and agronomic properties. The variation in agronomic properties was lower in 2007 and 2008 than in 2006, partly because of the SSD (single seed descent) in the M4 generation and partly because of the loss of late heading genotypes. The diversity was lowest in 2007, probably due to the extremely dry weather.

Effect of heat and drought stress on the structure and composition of arabinoxylan and β-glucan in wheat grain

The effects of heat (H), drought (D) and H+D (from 12th day after heading for 15 days) on the dietary fiber content and composition (arabinoxylan (AX) and β-glucan) of three winter wheat varieties (Plainsman V, Mv Magma and Fatima 2) were determined. Results showed that H and D stress decreased the TKW, the β-glucan contents of the seeds and the quantity of the DP3+DP4 units, while the protein and AX contents increased. The highest amounts of AX and proteins were in the H+D stressed samples with heat stress also increasing the water extractability (WE) of the AX. However, while the content of AX content was generally increased by all stresses, drought stress had negative effect on the AX content of the drought tolerant Plainsman V. Fatima 2 behaved similarly to Plainsman V as regards to its drought tolerance, but was very sensitive to heat stress, while Mv Magma was the most resistant to heat stress.

Identification, Cloning and Characterisation of a HMW-Glutenin Gene from an Old Hungarian Wheat Variety, Bánkúti 1201

Despite its good functional properties, the varietyBánkúti 1201 has been found to possess 2 + 12 or 3 + 12 allelecomposition on chromosome 1D. In order to determine the reason for itsquality traits a gene-specific PCR technique was applied in preliminaryexperiments to examine the HMW glutenin allele composition of thevariety. In the course of the analysis a fragment characteristic ofBánkúti 1201 was identified and the nucleotide sequence wasdetermined. This showed the presence of a 1Ax2* gene variantwhich, despite near homology, differed from the original 1Ax2* geneat one important point. At 1181 bp of the 1Ax2* sequencenucleotide exchange was observed which is the middle nucleotide of theTCT–TGT base triplet, involving the exchange of serine for cysteine. Thegene was designated 1Ax2*B. The presence of an extrasulphydryl group, like that of the extra cysteine in the 1Dx5 gene,facilitates the formation of further disulphide bonds, might lead to animprovement in gluten quality characters.

Effect of combined changes in culture medium and incubation conditions on the regeneration from immature embryos of elite varieties of winter wheat

In this study, tissue culture method for plant regeneration from immature embryos of elite Hungarian winter wheat varieties was established. The influence of the growth regulators and the concentration of macroelements in the regeneration medium and of the incubation temperature and light intensity on regeneration frequency were investigated. The most noticeable effect on regeneration frequency was achieved by simultaneously reducing both the incubation temperature to 23 °C and the concentration of macroelements in the regeneration medium to half-strength. This modification increased the average regeneration frequency from about 10–78%. Changes in the light intensity and temperature gave an average plant regeneration frequency of 83%.

Drought tolerance in cereals in terms of water retention, photosynthesis and antioxidant enzyme activities

Experiments were carried out on three bread wheat varieties, one barley and one durum wheat variety grown in pots in the phytotron and subjected to water withdrawal for 7 days during grain-filling. Leaf water loss, net assimilation rate and transpiration showed marked differences, allowing the genotypes to be ranked. Although the most resistant variety had the highest activity for ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR) and glutathione-S-transferase (GST), which did not rise further in response to drought and the most susceptible variety had the lowest values, which increased to the greatest extent under drought, the level of sensitivity could not be predicted for all the genotypes from the enzyme activity values alone. The largest increases were recorded for the APX, CAT and GR activities. In most genotypes the GR activity was correlated with that of GST, CAT and APX. Changes in the enzyme activities were observed after a decline in transpiration and photosynthesis. The range of soil moisture values over which the antioxidant enzyme activity levels remained relatively unchanged was a better indication of tolerance to drought than either basic or stress-induced activity levels.

Effects of temperature and light intensity on flowering of barley (Hordeum vulgare L.)

In order to analyse the effects of temperature (9-22 degreesC) and light intensity (170-576 micromol m(-2) s(-1)) on plant development two barley varieties with contrasting seasonal growth habits were included in a series of experiments consisting of controlled environment tests. The effect of constant (18 degrees C) and daily fluctuating (18/16 degrees C) temperature with a long photoperiod was also examined in a set of barley varieties including winter, facultative and spring barleys. Dicktoo with facultative growth habit was more sensitive to unfavourable conditions than Kompolti korai with winter growth habit; the flowering of Dicktoo was significantly delayed by sub- and supra-optimal temperatures and low light intensity accompanied by higher or fluctuating temperatures. The optimal temperature at flowering was also significantly lower for Dicktoo than for Kompolti korai (16.0 degrees C vs. 21.0 degrees C, respectively). Plant development was the fastest when there was no fluctuating environmental factor in the growing conditions and was significantly delayed with application of photo cycle. The addition of thermo cycle to photo cycle had an even stronger delaying effect. Facultative barleys were the most sensitive, followed by winter barleys, while spring barleys the least sensitive to the introduction of thermo cycle.