Mária Megyeri

Cytomolecular identification of individual wheat-wheat chromosome arm associations in wheat-rye hybrids

Chromosome pairing in the meiotic metaphase I of wheat-rye hybrids has been characterized by sequential genomic and fluorescent in situ hybridization allowing not only the discrimination of wheat and rye chromosomes, but also the identification of the individual wheat and rye chromosome arms involved in the chromosome associations. The majority of associations (93.8%) were observed between the wheat chromosomes. The largest number of wheat-wheat chromosome associations (53%) was detected between the A and D genomes, while the frequency of B-D and A-B associations was significantly lower (32 and 8%, respectively). Among the A-D chromosome associations, pairing between the 3AL and 3DL arms was observed with the highest frequency, while the most frequent of all the chromosome associations (0.113/cell) was found to be the 3DS-3BS. Differences in the pairing frequency of the individual chromosome arms of wheat-rye hybrids have been discussed in relation to the homoeologous relationships between the constituent genomes of hexaploid wheat.

Cytomolecular discrimination of the Am chromosomes of Triticum monococcum and the A chromosomes of Triticum aestivum using microsatellite DNA repeats

The cytomolecular discrimination of the Am- and A-genome chromosomes facilitates the selection of wheat-Triticum monococcum introgression lines. Fluorescence in situ hybridisation (FISH) with the commonly used DNA probes Afa family, 18S rDNA and pSc119.2 showed that the more complex hybridisation pattern obtained in T. monococcum relative to bread wheat made it possible to differentiate the Am and A chromosomes within homoeologous groups 1, 4 and 5. In order to provide additional chromosomal landmarks to discriminate the Am and A chromosomes, the microsatellite repeats (GAA)n, (CAG)n, (CAC)n, (AAC)n, (AGG)n and (ACT)n were tested as FISH probes. These showed that T. monococcum chromosomes have fewer, generally weaker, simple sequence repeat (SSR) signals than the A-genome chromosomes of hexaploid wheat. A differential hybridisation pattern was observed on 6Am and 6A chromosomes with all the SSR probes tested except for the (ACT)n probe. The 2Am and 2A chromosomes were differentiated by the signals given by the (GAA)n, (CAG)n and (AAC)n repeats, while only (GAA)n discriminated the chromosomes 3Am and 3A. Chromosomes 7Am and 7A could be differentiated by the lack of (GAA)n and (AGG)n signals on 7A. As potential landmarks for identifying the Am chromosomes, SSR repeats will facilitate the introgression of T. monococcum chromatin into wheat.

Selection of winter durum genotypes grown under conventional and organic conditions in different European regions

Quality and agronomic performance of 14 winter durum wheat genotypes (Gs) were examined in Austria, France and Hungary for 3 years. Heading time, wet gluten content, semolina yield and grain protein content are traits that showed G-dependent significant differences between the two management (M) systems examined (conventional and organic). Therefore, breeding for these traits could result in specifically adapted Gs for organic agriculture in different countries. Based on strong or moderately significant correlations between traits, gluten index and plant height could also be specifically selected in an indirect way. The need for environmentally specific selection for grain yield (GY) in later generations was also demonstrated. In general, varieties that had the highest performance in a given mega-environment (E) originated from that mega-E (except for yellow index). This finding provides evidence for the influence of the selection E, whether it is the M system or the growing region. As the French site fell into a distinct mega-E, it should be handled separately. The Hungarian site was found to be an ideal test E for selecting Gs with high adaptability for most of the quality traits, while the Austrian site could be used in selecting agronomic traits. This was also reflected in the breeding origin of the best winter durum Gs for each trait. Based on these findings, a partly separate winter durum selection program is recommended for organic and low input agriculture in each country. As a consequence, specific varieties adapted to sub-optimal growing conditions would support the emerging movement towards sustainable farming systems.

Stability analysis of wheat populations and mixtures based on the physical, compositional and processing properties of the seeds

Six cropping populations, three variety mixtures and one diversity population were developed from winter wheat varieties and studied for physical, compositional and end-use quality traits for three years (2011–2013) under different European climatic and management conditions in order to study the stability of these traits resulted by the genetic diversity. The beneficial compositional and nutritional properties of the populations were assessed, while variation and stability of the traits were analysed statistically. No significant differences were found among the populations in low-input and organic management farming systems in the physical, compositional and processing properties, but there was a difference in the stability of these traits. Most of the populations showed higher stability than the control wheat variety, and populations developed earlier had higher stability than those developed later. Furthermore, some populations were found to be especially unstable for some traits at certain sites (mostly at Austrian, Swiss and UK organic sites). Protein content of the populations was high (13.0–14.7%) without significant difference among them, but there was significant variation in their gluten content (28–36%) and arabinoxylan content (14.6–20.3 mg/g). The most outstanding population for both protein and arabinoxylan content was a Hungarian cropping population named ELIT-CCP. It was concluded that the diversity found in the mixtures and CCPs have stabilizing effect on the quality parameters, but a higher stability was observed under low-input than under organic conditions. These results could be beneficial not only for breeders but also for the consumers in the long run.