K. Mészáros

Effects of loci on chromosomes 2 (2H) and 7 (5H) on developmental patterns in barley ( Hordeum vulgare L.) under different photoperiod regimes

Abstract Heading-date in cereals is the final result of a number of interacting characters that include vernalization requirement, photoperiod sensitivity, and earliness per se. Progress in developing adapted varieties may be achieved by determining the chromosomal locations of genes controlling these characters. Nineteen doubled-haploid (DH) lines from the Dicktoo×Morex mapping population were phenotyped in controlled- environment photoperiod experiments to determine the role of two previously detected QTLs on the developmental patterns of barley. The QTLs are hypothesised to represent the effects of the Ppd and Sh2 loci on chromosomes 2 (2H) and 7 (5H), respectively. Alleles at the Ppd locus were found to be vary in response to photoperiod duration. Vernalization had some effect on alleles at both loci. The presence of early and late- flowering transgressive segregants in this mapping population can be explained by interactions between the Ppd and Sh2 loci. The Ppd and Sh2 loci are hypothesised to be homoeologous with the Ppd and Vrn1 loci of wheat.

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.

Barley (Hordeum vulgare L.) Marker Linkage Map: A Case Study of Various Marker Types and of Mapping Population Structure

A barley mapping population consisting of 96 doubled haploid lines of anther culture origin was developed from the varieties Dicktoo and Kompolti Korai, which represent diverse types with respect to geographical origin and ecological adaptation. Several molecular marker techniques were used in mapping: among the markers with known chromosome location, RFLP, STS and SSR markers were applied to identify linkage groups and for comparative mapping, while RAPD and AFLP markers, which have random binding but provide useful information on polymorphism, were employed to fill in the linkage groups with markers. A total of 496 markers were tested in the DH population, 246 of which were included in the linkage map after eliminating markers that were completely linked with each other. The ratio of markers with known chromosome location to random markers in the 1107 cM map was one to three, and the mean recombination distance between the markers was 4.5 cM. Application of various marker methods and the effect of the population structure on the development of marker linkage maps are discussed.

Cultivar identification by molecular markers

A total of 96 winter wheat (Triticum aestivum L.) cultivars registered in Hungary were analysed using 15 wheat microsatellite markers located on different chromosome arms. Analyses revealed 91 SSR alleles with sizes ranging from 123–239 base pairs. The total number of alleles per locus ranged from 2 (Gwm664 and Gwm415) to 11 (Gwm219) with an average number of 6.1. The polymorphic information content (PIC) values ranged from 0.06 to 0.85 with an average number of 0.60 for all markers. Several markers included allele sizes characteristic of a single or a small number of cultivars. At most 9 SSR markers were required to distinguish the 96 cultivars, so the simple sequence repeats could serve as a relatively cheap, rapid method for identifying winter wheat cultivars.

Bioinformatics Tool for Handling Molecular Data in Wheat Breeding

The research institute in Martonvasar is one of the largest agricultural research institutes in Hungary and in Central Europe. For many years now, the accumulated data on the extensive wheat breeding stocks has been handled and analysed using programs developed in the institute. The information system that has been elaborated and constantly improved can be used for keeping records of breeding stock, for planning field and laboratory experiments, for site-plant performance evaluation, for automated data collection, for the rapid evaluation of the results and for effective management of the pedigree, seed exchange and the institute’s cereal gene bank. The demand for the storage of molecular data and their use in breeding has increased parallel with the development of new, PCR-based markers. For this reason, informatics tools (data structure and software) suited to the design of marker-assisted selection experiments and the interpretation of the results have been developed as part of the existing Martonvasar wheat breeding information system. The aim was to link molecular data to the phenotypic information already available in the database and to make the results available to wheat breeders and geneticists. The interpretation of molecular data related to specific genotypes is of assistance in clarifying the genetic background of economically important phenotypic traits, in identifying markers linked to the useful genes or agronomic traits to be found in the genomics database, and in the selection of satisfactory parental partners for breeding. Marker assisted selection coupled with traditional breeding activities enables the breeder to make plant selections based on the presence of target genes. Conventional wheat breeding with the integrated molecular component allows breeders to more accurately and efficiently select defined sets of genes in segregating generations. The molecular data are stored in a relational database, the central element of which is the [DNASource] entity. This is used to collect and store information on gene sources arising during breeding. It is therefore linked both to the phenotypic data stored in the traditional breeding system (measurements, observations, laboratory data) and to the component parts of the new, molecular data structure ([PrimerBank], [Marker], [Allele] and [Gene]).