Gyula Vida

Dynamics of changes in the races and virulence of wheat powdery mildew in Hungary between 1971 and 1999

Important microevolutional processes have taken place in the wheat powdery mildew population over the last thirty years. There has been a considerable change in the race composition of the pathogen population and in the prevalent races. Of the 78 races identified, only eleven have “lived” for more than 15 years. Many races were only isolated in one or two years. The number of virulence genes rose from 2.03 in 1973 to 5.63 in 1993. On the basis of race composition and virulence the wheat powdery mildew population between 1971 and 1999 can be divided into four distinct groups. A large proportion of the powdery mildew isolates are virulent to most resistance genes. Complete resistance is provided by resistance genes Pm4a (Khapli) and partial resistance by Pm2+Mld (Halle st. 13471), Pm4b+ (TP 315/2) and Pm1+2+9 (Normandie). The majority of cultivated varieties carry the resistance gene Pm8 due to the presence of the 1B/1R translocation.

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.

Changes induced by powdery mildew in the salicylic acid and polyamine contents and the antioxidant enzyme activities of wheat lines

Investigations were made on four wheat (Triticum aestivum L.) lines under greenhouse conditions, in order to reveal the role of stress-protective materials, namely salicylic acid, polyamines and antioxidant enzymes in the level of tolerance to powdery mildew infection caused by Blumeria graminis (DC.) Speer f.sp. tritici Ém. Marchal. The four lines showed different levels of tolerance, assessed on the Saari-Prescott scoring scale: TC26 and TC33 proved to be susceptible and TC9 and TC19 resistant. In most of the lines, infection caused changes in the activities of antioxidant enzymes, especially in the case of guaiacol peroxidase. Four peroxidase isoenzymes, which responded differently to powdery mildew infection could be detected by gel electrophoresis. Infection had only a slight effect on the levels of salicylic acid (free and bound forms) in inoculated plants; while the levels of polyamines, especially spermidine and spermine increased after infection. Correlation analysis was also performed to examine how close a relationship exists between the parameters investigated. It was concluded that salicylic acid, polyamines and antioxidant enzymes have an important role in plant responses and defence mechanisms during this biotic stress and that in some cases there were significant relationships between them. However the levels of these compounds either initially or after pathogen inoculation, could not explain the degree of tolerance to powdery mildew in the four wheat lines investigated.

Breeding for breadmaking quality using old Hungarian wheat varieties

Due to their broad population diversity, old wheat varieties or landraces play an important role in increasing the genetic variability of agronomic traits. On these grounds, an analysis was made of the high molecular weight (HMW) glutenin subunit composition of the old Hungarian wheat variety Bankuti 1201. It was found that several genotypes with differing breadmaking qualities can be distinguished for this character. When using old varieties in breeding, it is possible to broaden the genetic background of characters responsible for breadmaking quality by separating the populations. A more detailed analysis of the protein composition of germplasm created in this way will be required to obtain a better understanding of this complex character for its conscious introduction into breeding programmes.

Validity of selected DNA markers for breeding leaf rust resistant wheat

The set of 44 near-isogenic lines of spring wheat cv. Thatcher and wheat genotypes known to carry specific leaf rust resistance genes were included in the present study for the preliminary validation of twelve STS and SCAR markers linked to leaf rust resistance genes Lr9, Lr19, Lr20, Lr21, Lr24, Lr25, Lr26, Lr28, Lr29, Lr37. Seven Lr genes were specifically tagged by STS and SCAR markers. The presence of genes Lr9, Lr19, Lr20, Lr24, Lr28, Lr29, Lr37 in the tested plant materials was confirmed by a unique amplification of markers SCS5 550, SCS265 512 and SCS253 736, STS638, SCS73 719, SCS421 570, IPY10 and Lr29F24/R24, cslVrgal3, PS10R/L, respectively. Evaluation of the repeatability and the reliability of selected markers (pTAG621 for Lr1, STS683 for Lr20, D14L for Lr21, Lr25F20/R19 for Lr25, Lr29F24/R24, IPY10 for Lr29, cslVrgal3 for Lr37 and PS10R/L for Lr47) across four European laboratories and PCR conditions demonstrated the usability of STS638, Lr29F24/R24, IPY10, cslVrgal3 and PS10R/L markers in marker-assisted selection. STS markers pTAG621 for gene Lr1, D14L for gene Lr21, Lr25F20/R19 for gene Lr25 were found to be unsuitable for effective screening of large segregating populations in breeding programs.

New Insights into the Life Cycle of the Wheat Powdery Mildew: Direct Observation of Ascosporic Infection in Blumeria graminis f. sp. tritici

Although Blumeria graminis is an intensively studied pathogen, an important part of its life cycle (namely, the way ascospores initiate primary infections on cereal leaves) has not yet been explored in detail. This study reports, for the first time, the direct observation of this process in B. graminis f. sp. tritici using light and confocal laser-scanning microscopy. All the germinated ascospores produced a single germ tube type both in vitro and on host plant surfaces; therefore, the ascosporic and conidial germination patterns are markedly different in this fungus, in contrast to other powdery mildews. Germinated ascospores penetrated the epidermal cells of wheat leaves and produced haustoria as known in the case of conidial infections. This work confirmed earlier studies reporting that B. graminis chasmothecia collected from the field do not contain mature ascospores, only asci filled with protoplasm; ascospore development is induced by moist conditions and is a fast process compared with other powdery mildews. Although ascosporic infections are frequent in B. graminis f. sp. tritici in the field, as shown by this study and other works as well, a recent analysis of the genomes of four isolates revealed the signs of clonal or near-clonal reproduction. Therefore, chasmothecia and ascospores are probably more important as oversummering structures than genetic recombination factors in the life cycle of this pathogen.

Response of wheat fungal diseases to elevated atmospheric CO2 level

Infection with fungal pathogens on wheat varieties with different levels of resistance was tested at ambient (NC, 390 ppm) and elevated (EC, 750 ppm) atmospheric CO2 levels in the phytotron. EC was found to affect many aspects of the plant-pathogen interaction. Infection with most fungal diseases was usually found to be promoted by elevated CO2 level in susceptible varieties. Powdery mildew, leaf rust and stem rust produced more severe symptoms on plants of susceptible varieties, while resistant varieties were not infected even at EC. The penetration of Fusarium head blight (FHB) into the spike was delayed by EC in Mv Mambo, while it was unaffected in Mv Regiment and stimulated in Mv Emma. EC increased the propagation of FHB in Mv Mambo and Mv Emma. Enhanced resistance to the spread of Fusarium within the plant was only found in Mv Regiment, which has good resistance to penetration but poor resistance to the spread of FHB at NC. FHB infection was more severe at EC in two varieties, while the plants of Mv ...

Genomic Analysis of the Natural Population of Wheat dwarf virus in Wheat from China and Hungary

Abstract During the last decade, the leafhopper transmitted Wheat dwarf virus (WDV) has become a serious problem both in northwestern China and Hungary. In order to study the molecular diversity and population structure of WDV in these two countries, 39 Chinese isolates and 16 Hungarian isolates were collected from different regions of China and Hungary, and their genomes were sequenced. All isolates belonged to the wheat strain of WDV and showed limited genetic diversity. The highest and lowest nucleotide sequence identities among isolates from China and Hungary were 99.9 and 90%, respectively. In all isolates, the lowest nucleotide sequence identity was 89.5% between MO10-1 and KP10-5, which were collected from Martonvasar and Kompolt, Hungary. Phylogenetic analyses showed the genome sequences of 55 WDV isolates belong to two big clades, but no clear correlation to geographical location. Population difference analyses indicated that the Chinese and Hungarian WDV populations have no significant difference. The regions in WDV genome with relatively low nucleotide diversities represented protein coding regions suggested that these regions evolved under negative selection, and might be one of the causes restricting the number of genetic variants.

Change in water stress resistance of cereals due to atmospheric CO 2 enrichment

Oil rape is a valuable fodder because in early spring and late autumn it produces green forage used for the nutrition of domestic animals. It has been replacing sunflower and soy in colder and wetter regions. It is additionally advantageous because it leaves behind more nitrogen in soil, which is beneficial to other plants in plant rotation. There are some possible ways for the fixation of nitrogen in soil and they are as follows: by the means of oil rape straw ; by relatively long roots ; by the action of nitrogen bacteria, which perform the nitrogen synthesis within their root system, which is the case in some leguminous plants. Oil seed rape is expected to be wider used in crop rotation of West and Middle Europe, Croatia included. Due to this various sorts have been introduced and potential positive impacts have been studied in order to boost the process. This paper presents information on barley and wheat yield in case when they were sown after oil seed rape and corn. The aim of the research is to determine the presence of positive impacts upon the soil with special attention paid to a potential increase of nitrogen content after oil seed rape was grown. The preceding crops had statistically significant effect. Rape yield was significantly higher compared to the one with corn as preceding crops. Very similar results were obtained in 2007.The maize hybrids seed from three different FAO groups (FAO 400, FAO 500 and FAO 600) in four fractions (KO, KP, SO and SP) produced in two climatically different years (extremely dry 2000 and extremely wet 2001) had been different in quality and chemical composition. The effects of year, genetic specifity and seed fraction at the kernel mass, chemical composition (starch, proteins, cellulose, oil and moisture content) and seed vigour have been evaluated. The influence of agroecological conditions during two production years have been exposed at seed chemical composition and vigour indicators (cold test – CT and bulk seed electrical conductivity - EC). The genetic specificity and seed fraction had significant influence at all tested indices, with the exception of the influence of the fraction at the starch content

McGISH identification and phenotypic description of leaf rust and yellow rust resistant partial amphiploids originating from a wheat × Thinopyrum synthetic hybrid cross.

A Thinopyrum intermedium × Thinopyrum ponticum synthetic hybrid wheatgrass is an excellent source of leaf and stem rust resistance produced by N.V.Tsitsin. Wheat line Mv9kr1 was crossed with this hybrid (Agropyron glael) in Hungary in order to transfer its advantageous agronomic traits into wheat. As the wheat parent was susceptible to leaf rust, the transfer of resistance was easily recognizable in the progenies. Three different partial amphiploid lines with leaf rust resistance were selected from the wheat/Thinopyrum hybrid derivatives by multicolour genomic in situ hybridization. Chromosome counting on the partial amphiploids revealed 58 chromosomes (18 wheatgrass) in line 194, 56 (14 wheatgrass) in line 195 and 54 (12 wheatgrass) in line 196. The wheat chromosomes present in these lines were identified and the wheatgrass chromosomes were characterized by fluorescence in situ hybridization using the repetitive DNA probes Afa-family, pSc119.2 and pTa71. The 3D wheat chromosome was missing from the lines. Molecular marker analysis showed the presence of the Lr24 leaf rust resistance gene in lines 195 and 196. The morphological traits were evaluated in the field during two consecutive seasons in two different locations.